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Effect of pituitary surgery in patients with acromegaly on adiponectin serum concentrations and alanine aminotransferase activity
Clinica Chimica Acta 352 (2005) 175 – 181 www.elsevier.com/locate/clinchim
Effect of pituitary surgery in patients with acromegaly on adiponectin serum concentrations and alanine aminotransferase activity Peter Wieslia,*, Rene´ Bernaysb, Michael Br7ndlea, Cornelia Zwimpfera, Heidi Seilera, Jqrgen Zapf a, Giatgen A. Spinasa, Christoph Schmida a
Department of Internal Medicine, Division of Endocrinology and Diabetes, University Hospital of Zurich, CH-8091 Zurich, Switzerland b Department of Neurosurgery, University Hospital of Zurich, CH-8091 Zurich, Switzerland Received 27 May 2004; received in revised form 24 September 2004; accepted 24 September 2004
Abstract Background: Thiazolidinediones increase adiponectin concentrations, improve insulin sensitivity and fatty liver disease (reflected by decreased alanine aminotransferase [ALT] activity) in type 2 diabetes. This study was performed to test the effect of neurosurgery in acromegaly (sharing at baseline insulin resistance but not increased visceral fat with type 2 diabetes) on insulin sensitivity, adiponectin concentrations and ALT activity. Methods: Sixteen patients with acromegaly undergoing pituitary surgery (and 16 patients with type 2 diabetes treated with pioglitazone) were included. Insulin sensitivity, adiponectin concentrations and ALT activity were determined at baseline and after 4 months. Results: Pituitary surgery in acromegalic patients increased adiponectin concentrations from mean (FS.D.) 9.3F3.8 to 10.2F4.4 mg/L ( pb0.05). HOMA scores fell from 6.8F4 at baseline to 3.5F0.9 following neurosurgery ( pb0.005) and ALT activity decreased from median (range) 21 (13–30) to 13 (10–42) U/L ( pb0.05). In type 2 diabetics, pioglitazone treatment increased adiponectin concentrations; HOMA scores and ALT activity fell significantly. Conclusion: Pituitary surgery in patients with acromegaly led to a marked increase in insulin sensitivity and a slight increase in adiponectin serum concentrations, whereas ALT activity significantly decreased. D 2004 Elsevier B.V. All rights reserved. Keywords: Acromegaly; Diabetes mellitus; Adiponectin; Insulin sensitivity; ALT
1. Introduction * Corresponding author. Tel.: +41 1 255 36 20; fax: +41 1 255 44 47. E-mail address: [email protected] (P. Wiesli). 0009-8981/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.cccn.2004.09.022
Adiponectin is an adipocyte-specific glycoprotein that sensitises liver and skeletal muscle to the action of insulin [1,2]. Circulating adiponectin concentra-
176
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181
tions have been shown to be positively correlated with insulin sensitivity and thus, decreased adiponectin concentrations have been described in insulin resistant subjects including patients with type 2 diabetes and obesity [3–5]. In patients with type 2 diabetes, an increased hepatic fat content was found to be an important determinant of decreased hepatic insulin sensitivity [6,7]. Thiazolidinediones increase adiponectin gene expression and plasma levels [8,9]. In patients with type 2 diabetes, treatment with pioglitazone reduced visceral fat, hepatic fat content, and alanine aminotransferase (ALT) enzyme activity [7,10]. The decrease in hepatic fat and improvement in hepatic insulin sensitivity were closely associated with the increase in plasma adiponectin concentrations [7]. Moreover, treatment with recombinant adiponectin alleviated nonalcoholic steatohepatitis (NASH) in mice and pioglitazone treatment improved NASH in non-diabetic humans [11]. Patients with acromegaly and type 2 diabetes share many common features including insulin resistance, impaired glucose tolerance and increased incidence of macrovascular complications [12]. However, whereas visceral fat is increased in patients with type 2 diabetes, it is decreased in patients with acromegaly [6,13]. To the best of our knowledge, only one crosssectional study investigated adiponectin serum concentrations in patients with acromegaly [14]. Despite decreased insulin sensitivity in acromegalic subjects, adiponectin concentrations were found to be increased when compared to healthy controls. The aim of this study was to assess the effect of pituitary surgery in patients with acromegaly and the effect of pioglitazone therapy in patients with type 2 diabetes on insulin sensitivity, adiponectin serum concentrations, and ALT activity.
2. Materials and methods Sixteen consecutive patients with newly diagnosed acromegaly at the University Hospital of Zurich were included. Three acromegalic patients were excluded: one because of insulin-dependent diabetes mellitus, one because of an oesophageal cancer undergoing surgery and one because of a salmonella-induced coxitis. Diagnosis of acromegaly was established by clinical findings, elevated IGF 1 concentrations and
lack of growth hormone (GH) suppression to b1 Ag/L during an 75 g oral glucose tolerance test in all patients. MR imaging technique revealed pituitary macroadenomas (z10 mm in diameter) in 13 and microadenomas in 3 patients. All patients underwent transsphenoidal pituitary surgery as primary treatment. In addition, 16 patients with type 2 diabetes mellitus undergoing a therapy with pioglitazone were included. Exclusion criteria were insulin therapy, contraindications against pioglitazone, women without an effective contraception, and serious concomitant illness. From the 16 patients with type 2 diabetes included, 5 were on diet, 7 on metformin, 2 on repaglinide and 2 patients had a combination therapy of metformin and repaglinide. Therapy with pioglitazone 30 mg daily was started in all patients, the dose remained unchanged for 4 months. 2.1. Laboratory investigations All parameters were determined at baseline and at a mean follow-up period of 16–18 weeks following pituitary surgery or the start of pioglitazone therapy. All medications were discontinued the evening before the study, blood samples were drawn after an overnight fast. ALT enzyme activity was determined at the Institute for Clinical Chemistry of the University Hospital of Zurich on a Roche-Hitachi Modular Clinical Chemistry analyzer using commercial tests (with addition of pyridoxal phosphate) from Roche Diagnostics (Mannheim, Germany). Serum concentrations of adiponectin were measured using a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) validated for serum and plasma (R&D Systems Europe, Abingdon, UK). The intra-assay coefficient of variation was 3.4% (at 69.9 ng/ml), the inter-assay coefficient 5.8% (at 74.4 ng/ml). For the determination of insulin-like growth factor 1 (IGF 1), carrier proteins were removed by Sep-PakR chromatography according to the instructions of the supplier (Waters Associates, Milford, MA) and IGF 1 was determined by radioimmunoassay (RIA) [15]. Acid-labile subunit (ALS) was measured using active total ALS ELISA, an enzymatically amplified btwo-stepQ sandwich-type immunoassay (Diagnostic Systems Laboratories, Webster, Texas, USA). Insulin was measured by a solid-phase RIA (CIS Bio international, Oris Industries, Gif-Sur-
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181
Yvette, France); normal overnight fasting range provided by the manufacturer was 30–138 pmol/L. Insulin resistance was estimated using homeostasis model assessment (HOMA) [16]. 2.2. Statistical analysis Data were presented as means and standard deviations (S.D.s) when not otherwise stated. Values before and after treatment within the two groups were analyzed using the Wilcoxon signed Rank test. Comparison between the groups of patients were evaluated by the Wilcoxon Rank sum test. A p-value b0.05 was considered statistically significant.
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Table 2 (A) Pre- and postoperative findings in 16 patients with acromegaly Preoperative Postoperative IGF-1 (Ag/L) 693F314 ALS (Ag/L) 30.1F10 Body weight (kg) 80.5F12.8 Waist circumference (cm) 94.4F6.5 Plasma glucose (mmol/L) 5.6F0.9 Insulin (pmol/L) 196F114 HOMA score 6.8F4 Triglycerides (mmol/L) 1.1F0.4 HDL-cholesterol (mmol/L) 1.5F0.3 ALT (U/L) 21F5 Adiponectin (mg/L) 9.3F3.8
255F91 17.2F7.4 79.8F13.1 95.8F8.5 5.1F1.1 113F36 3.5F0.9 0.8F0.3 1.6F0.2 17F9 10.2F4.4
p* pb0.005 pb0.005 ns ns pb0.05 pb0.005 pb0.005 pb0.05 ns pb0.05 pb0.05
(B) Findings in 16 patients with type 2 diabetes at baseline and after 4 months of therapy with pioglitazone 30 mg daily At baseline After 4 months p*
3. Results Baseline characteristics of all 32 patients are shown in Table 1. No significant differences were found between patients with acromegaly and type 2 diabetes concerning gender, duration of disease, BMI, body weight, fasting insulin concentration, HOMA score, triglycerides, HDL-cholesterol and ALT activity. Patients with type 2 diabetes were significantly older (61F9 years) compared to the patients with acromegaly (48F16 years). Waist circumference, plasma glucose and HbA1c were significantly higher in Table 1 Baseline characteristics
Sex (m/f) Age (years) Duration of disease (years) Weight (kg) BMI (kg/m2) Waist circumference (cm) Plasma glucose (mmol/L) Insulin (pmol/L) HOMA score HbA1c (%) Triglycerides (mmol/L) HDL-cholesterol (mmol/L) ALT (U/L) Adiponectin (mg/L)
Type 2 diabetes (n=16)
Acromegaly (n=16)
p*
12/4 61F9 6F5 83F11 29.7F4.5 103F8 8.6F2.6 140F58 7.6F4.3 7.4F0.9 1.4F0.8 1.4F0.4 26F19 6.1F3.5
8/8 48F16 6F4 81F13 27.1F3.5 94F7 5.6F0.9 196F114 6.8F4 6F0.8 1.1F0.4 1.5F0.3 21F5 9.3F3.8
ns pb0.05 ns ns ns pb0.005 pb0.005 p=0.08 ns pb0.005 ns ns ns pb0.005**
* By Wilcoxon Rank sum. ** Not statistically different when adjusted for age.
Body weight (kg) 83.4F11.2 84.8F11.7 Waist circumference (cm) 103.4F7.9 105.1F8.2 Plasma glucose (mmol/L) 8.6F2.6 7.8F1.6 HbA1c (%) 7.4F0.9 7F0.5 Insulin (pmol/L) 139F58 114F42 HOMA score 7.6F4.3 5.4F2.1 Triglycerides (mmol/L) 1.4F0.8 1.4F0.8 HDL-cholesterol (mmol/L) 1.4F.0.4 1.4F0.3 ALT (U/L) 26F19 20F10 Adiponectin (mg/L) 6.1F3.4 11.5F4.9
pb0.05 pb0.05 pb0.05 p=0.06 pb0.05 pb0.05 ns ns pb0.05 pb0.005
* By Wilcoxon Signed Rank test.
patients with type 2 diabetes compared to patients with acromegaly. Baseline adiponectin concentrations were 6.1F3.5 mg/L in patients with type 2 diabetes, i.e., lower than in acromegalic patients (9.3F3.8 mg/L). This difference was no more significant when adiponectin levels were adjusted for age ( p=0.053). Findings in patients with type 2 diabetes undergoing treatment with pioglitazone are illustrated in Table 2. In patients with type 2 diabetes treated with pioglitazone, body weight increased from 83.4F11.2 to 84.8F11.7 kg ( pb0.05) and waist circumference from 103 to 105 cm ( pb0.05). Fasting plasma glucose concentration decreased from 8.6F2.6 to 7.8F1.6 mmol/L ( pb0.05) and HbA1c from 7.4F0.9 to 7F0.5% ( p=0.06). In the same period, fasting insulin concentrations decreased from 139F58 to 114F42 pmol/L ( pb0.05). Triglycerides and HDL-cholesterol concentrations remained unchanged, but ALT activity decreased from median 20 (range 14–86) to 17 (9–46) U/L ( pb0.05; mean FSD in Table 2).
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Pre- and postoperative findings in acromegalic patients are shown in Table 2. Transsphenoidal surgery resulted in effective tumor debulking as documented by at least partial decreases in disease activity and IGF 1 serum concentrations. IGF 1 concentrations decreased from 693F314 to 255F91 Ag/L ( pb0.005). Ten patients (63%) were cured as defined by clinical and biochemical criteria, i.e., both normal age-adjusted IGF
1 serum concentration and GH suppressed to b1 ng/ml during the oral glucose tolerance test, an often cited definition of cure in patients with acromegaly [17]. ALS decreased in each individual patient, from 30.1F10 to 17.2F7.4 mg/L ( pb0.005). Body weight and waist circumference did not significantly change following neurosurgery (as assessed 4 months later). Improved insulin sensitivity was indicated by signifi-
Fig. 1. HOMA and adiponectin serum concentrations in 16 patients with type 2 diabetes at baseline and following treatment with pioglitazone and in 16 patients with acromegaly at baseline and following pituitary surgery.
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181
cant decreases in plasma glucose and serum insulin concentrations, as well as in the HOMA scores. In the same period, ALT activity decreased from median 21 (13–30) to 13 (10–42) U/L ( pb0.05; mean F SD in Table 2), and triglyceride concentrations fell from 1.1F0.4 to 0.8F0.3 mmol/L ( pb0.05). HOMA scores and adiponectin concentrations of each individual patient are shown in the figure. HOMA scores decreased in both groups of patients, indicating improved insulin sensitivity in patients with type 2 diabetes following treatment with pioglitazone as well as in acromegalic patients following pituitary surgery. In patients with type 2 diabetes treated with pioglitazone, HOMA scores decreased from 7.6F4.3 to 5.4F2.1 ( pb0.05). In the same period, adiponectin concentrations increased markedly, from 6.1F3.4 to 11.5F4.9 mg/L ( pb0.005). As shown in Fig. 1, adiponectin concentrations increased in each individual patient. In patients with acromegaly, HOMA score dropped from 6.8F4 at baseline to 3.5F0.9 ( pb0.005) following pituitary surgery. In the same period, adiponectin concentrations increased slightly but significantly from 9.3F3.8 to 10.2F4.4 mg/L ( pb0.05). Adiponectin concentrations increased in 13 of 16 (81%) patients.
4. Discussion Our data confirm that thiazolidinedione drugs increase circulating adiponectin concentrations and improve insulin sensitivity in patients with type 2 diabetes, as illustrated by the drop of HOMA scores [18]. Although we did not measure body composition and visceral fat in our study, the increase in waist circumference following pioglitazone therapy might be assigned to an increase in subcutaneous rather than visceral fat because the latter usually decreases [18]. In a previous study, pioglitazone treatment reduced hepatic fat content and decreased ALT enzyme activity; the latter observation is confirmed by our data [7]. Thus, the increase in adiponectin concentrations and the decrease in ALT activity following pioglitazone therapy in patients with type 2 diabetes may be related to improved insulin sensitivity and a decrease in hepatic fat content. In contrast to patients with type 2 diabetes, patients with untreated acromegaly have decreased visceral fat
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[19]. In our study, waist circumference was significantly lower in patients with acromegaly than in diabetic subjects. Despite comparably impaired insulin sensitivity and statistically not different body weight, baseline adiponectin concentrations in patients with acromegaly were higher than in diabetic subjects. This difference in adiponectin concentrations was observed irrespective of the gender of the patients (higher levels have been reported in women) [20] but was not statistically significant when adiponectin levels were adjusted for age. A previous study showed higher adiponectin concentrations in patients with acromegaly compared to weight-matched healthy controls [14]. Herein, we describe for the first time the change of adiponectin serum concentrations in patients with acromegaly undergoing pituitary surgery. The efficacy of tumour debulking was illustrated by the drop of the GH-dependent serum proteins IGF 1 and ALS. The former (IGF 1) is predominantly and the latter (ALS) is exclusively produced by hepatocytes. Following surgery, we found a modest but significant increase in adiponectin concentrations in 13 of 16 patients. This finding was in parallel with the improved insulin sensitivity (correlation was not statistically significant). However, whereas improvement of insulin sensitivity following pituitary surgery was definite, increase in adiponectin was only modest. Apparently, parameters potentially affecting adiponectin concentrations (insulin sensitivity and visceral fat) counteract each other in acromegalic subjects. As indicated above, the increased insulin sensitivity following pituitary surgery occurred in a condition where fat mass is initially low. Within 4 months following surgery, visceral fat may not be restored to normal, a fact which may account for an attenuated rise in adiponectin concentrations despite markedly increased insulin sensitivity [13]. However, visceral fat or body composition were not measured in our study. In recent studies, treatment with GH in GHdeficient patients had no effect on circulating adiponectin concentrations. In one study, no significant change in adiponectin was observed despite a reduction in fat mass and a decrease in insulin sensitivity following GH therapy [21]. Another study confirmed that the change in body composition in GH-deficient patients treated with GH was not associated with a change in circulating adiponectin concentrations [22]. In that study, insulin sensitivity was not significantly
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altered by GH therapy. Thus, adiponectin concentrations of patients with GH deficiency and excess, respectively, seem to be regulated in a complex manner warranting further studies. Interestingly, the increase of adiponectin following pituitary surgery was associated with a modest but significant decrease of ALT enzyme activity within the normal range. A relevant limitation of our study is that we did not measure hepatic fat content. Thus, we cannot conclude whether this decrease in ALT activity reflects a decrease in intrahepatic fat content. To the best of our knowledge, no data exist concerning the hepatic fat content in acromegalic patients. Whether a specific pathophysiological condition in acromegalic patients undergoing pituitary surgery (i.e., inflammation, reduced hepatic fat, decrease in GH excess, etc.) is responsible for the postoperative decrease in ALT activity cannot be derived from our data. Because the determination of the enzyme activity was performed with the addition pyridoxal phosphate, a transient postoperative vitamin B6 deficiency interfering with the determination of ALT can be ruled out [23]. Longterm administration of adiponectin improved insulin sensitivity and decreased liver, muscle and plasma triglycerides in diabetic mice [24,25]. In our study, the modest increase in adiponectin in acromegalic patients undergoing pituitary surgery was associated with improved insulin sensitivity as well as a decrease in ALT activity and plasma triglyceride concentrations. However, whether the change in adiponectin serum concentration was causal for the liver functionrelated changes observed cannot be derived from our data. In conclusion, we have demonstrated that pituitary surgery in patients with acromegaly led to a marked increase in insulin sensitivity and a slight but significant increase in adiponectin serum concentrations, ALT enzyme activity significantly decreased over the same period. References [1] Berg AH, Combs TP, Du X, Brownlee M, Scherer PE. The adipocyte-secreted protein Acrp30 enhances hepatic insulin action. Nat Med 2001;7:947 – 53. [2] Yamauchi T, Kamon J, Ito Y, Tsuchida A, Yokomizo T, Kita S, et al. Cloning of adiponectin receptors that mediate antidiabetic metabolic effects. Nature 2003;423:762 – 9.
[3] Arita Y, Kihara S, Ouchi N, Takahashi M, Maeda K, Miyagawa J, et al. Paradoxical decrease of an adipose-specific protein, adiponectin, in obesity. Biochem Biophys Res Commun 1999;257:79 – 83. [4] Hotta K, Funahashi T, Arita Y, Takahashi M, Matsuda M, Okamoto Y, et al. Plasma concentrations of a novel, adiposespecific protein, adiponectin, in type 2 diabetic patients. Arterioscler Thromb Vasc Biol 2000;20:1595 – 9. [5] Weyer C, Funahashi T, Tanaka S, Hotta K, Matsuzawa Y, Pratley RE, et al. Hypoadiponectinemia in obesity and type 2 diabetes: close association with insulin resistance and hyperinsulinemia. J Clin Endocrinol Metab 2001;86:1930 – 5. [6] Yamashita S, Nakamura T, Shimomura I, Nishida M, Yoshida S, Kotani K, et al. Insulin resistance and body fat distribution. Diabetes Care 1996;19:287 – 91. [7] Bajaj M, Suraamornkul S, Piper P, Hardies LJ, Glass L, Cersosimo E, et al. Decreased plasma adiponectin concentrations are closely related to hepatic fat content and hepatic insulin resistance in pioglitazone-treated type 2 diabetic patients. J Clin Endocrinol Metab 2004;89:200 – 6. [8] Maeda N, Takahashi M, Funahashi T, Kihara S, Nishizawa H, Kishida K, et al. PPARgamma ligands increase expression and plasma concentrations of adiponectin, an adipose-derived protein. Diabetes 2001;50:2094 – 9. [9] Yu JG, Javorschi S, Hevener AL, Kruszynska YT, Norman RA, Sinha M, et al. The effect of thiazolidinediones on plasma adiponectin levels in normal, obese, and type 2 diabetic subjects. Diabetes 2002;51:2968 – 74. [10] Hirose H, Kawai T, Yamamoto Y, Taniyama M, Tomita M, Matsubara K, et al. Effects of pioglitazone on metabolic parameters, body fat distribution, and serum adiponectin levels in Japanese male patients with type 2 diabetes. Metabolism 2002;51:314 – 7. [11] Promrat K, Lutchman G, Uwaifo GI, Freedman RJ, Soza A, Heller T, et al. A pilot study of pioglitazone treatment for nonalcoholic steatohepatitis. Hepatology 2004;39:188 – 96. [12] Bengtsson BA, Eden S, Ernest I, Oden A, Sjogren B. Epidemiology and long-term survival in acromegaly. A study of 166 cases diagnosed between 1955 and 1984. Acta Med Scand 1988;223:327 – 35. [13] O’Sullivan AJ, Kelly JJ, Hoffman DM, Freund J, Ho KK. Body composition and energy expenditure in acromegaly. J Clin Endocrinol Metab 1994;78:381 – 6. [14] Silha JV, Krsek M, Hana V, Marek J, Jeskova J, Weiss V, et al. Perturbations in adiponectin, leptin and resistin levels in acromegaly: lack of correlation with insulin resistance. Clin Endocrinol (Oxf) 2003;58:736 – 42. [15] Zapf J, Walter H, Froesch ER. Radioimmunological determination of insulinlike growth factors I and II in normal subjects and in patients with growth disorders and extrapancreatic tumor hypoglycemia. J Clin Invest 1981;68: 1321 – 30. [16] Matthews DR, Hosker JP, Rudenski AS, Naylor BA, Treacher DF, Turner RC. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia 1985; 28:412 – 9.
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181 [17] Giustina A, Barkan A, Casanueva FF, Cavagnini F, Frohman L, Ho K, et al. Criteria for cure of acromegaly: a consensus statement. J Clin Endocrinol Metab 2000;85:526 – 9. [18] Miyazaki Y, Mahankali A, Matsuda M, Mahankali S, Hardies J, Cusi K, et al. Effect of pioglitazone on abdominal fat distribution and insulin sensitivity in type 2 diabetic patients. J Clin Endocrinol Metab 2002;87:2784 – 91. [19] Bengtsson BA, Brummer RJ, Bosaeus I. Growth hormone and body composition. Horm Res 1990;33(Suppl. 4):19 – 24. [20] Nishizawa H, Shimomura I, Kishida K, Maeda N, Kuriyama H, Nagaretani H, et al. Androgens decrease plasma adiponectin, an insulin-sensitizing adipocyte-derived protein. Diabetes 2002;51:2734 – 41. [21] Eden EB, Burman P, Holdstock C, Karlsson FA. Effects of growth hormone (GH) on ghrelin, leptin, and adiponectin in GH-deficient patients. J Clin Endocrinol Metab 2003; 88:5193 – 8.
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[22] Hana V, Silha JV, Justova V, Lacinova Z, Stepan JJ, Murphy LJ. The effects of GH replacement in adult GH-deficient patients: changes in body composition without concomitant changes in the adipokines and insulin resistance. Clin Endocrinol (Oxf) 2004;60:442 – 50. [23] Taes YE, Bernard DR, Delanghe JR. Homocysteine and methionine transamination. Am J Kidney Dis 2003;41:898. [24] Fruebis J, Tsao TS, Javorschi S, Ebbets-Reed D, Erickson MR, Yen FT, et al. Proteolytic cleavage product of 30-kDa adipocyte complement-related protein increases fatty acid oxidation in muscle and causes weight loss in mice. Proc Natl Acad Sci U S A 2001;98:2005 – 10. [25] Combs TP, Berg AH, Obici S, Scherer PE, Rossetti L. Endogenous glucose production is inhibited by the adiposederived protein Acrp30. J Clin Invest 2001;108:1875 – 81.
Effect of pituitary surgery in patients with acromegaly on adiponectin serum concentrations and alanine aminotransferase activity Peter Wieslia,*, Rene´ Bernaysb, Michael Br7ndlea, Cornelia Zwimpfera, Heidi Seilera, Jqrgen Zapf a, Giatgen A. Spinasa, Christoph Schmida a
Department of Internal Medicine, Division of Endocrinology and Diabetes, University Hospital of Zurich, CH-8091 Zurich, Switzerland b Department of Neurosurgery, University Hospital of Zurich, CH-8091 Zurich, Switzerland Received 27 May 2004; received in revised form 24 September 2004; accepted 24 September 2004
Abstract Background: Thiazolidinediones increase adiponectin concentrations, improve insulin sensitivity and fatty liver disease (reflected by decreased alanine aminotransferase [ALT] activity) in type 2 diabetes. This study was performed to test the effect of neurosurgery in acromegaly (sharing at baseline insulin resistance but not increased visceral fat with type 2 diabetes) on insulin sensitivity, adiponectin concentrations and ALT activity. Methods: Sixteen patients with acromegaly undergoing pituitary surgery (and 16 patients with type 2 diabetes treated with pioglitazone) were included. Insulin sensitivity, adiponectin concentrations and ALT activity were determined at baseline and after 4 months. Results: Pituitary surgery in acromegalic patients increased adiponectin concentrations from mean (FS.D.) 9.3F3.8 to 10.2F4.4 mg/L ( pb0.05). HOMA scores fell from 6.8F4 at baseline to 3.5F0.9 following neurosurgery ( pb0.005) and ALT activity decreased from median (range) 21 (13–30) to 13 (10–42) U/L ( pb0.05). In type 2 diabetics, pioglitazone treatment increased adiponectin concentrations; HOMA scores and ALT activity fell significantly. Conclusion: Pituitary surgery in patients with acromegaly led to a marked increase in insulin sensitivity and a slight increase in adiponectin serum concentrations, whereas ALT activity significantly decreased. D 2004 Elsevier B.V. All rights reserved. Keywords: Acromegaly; Diabetes mellitus; Adiponectin; Insulin sensitivity; ALT
1. Introduction * Corresponding author. Tel.: +41 1 255 36 20; fax: +41 1 255 44 47. E-mail address: [email protected] (P. Wiesli). 0009-8981/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.cccn.2004.09.022
Adiponectin is an adipocyte-specific glycoprotein that sensitises liver and skeletal muscle to the action of insulin [1,2]. Circulating adiponectin concentra-
176
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181
tions have been shown to be positively correlated with insulin sensitivity and thus, decreased adiponectin concentrations have been described in insulin resistant subjects including patients with type 2 diabetes and obesity [3–5]. In patients with type 2 diabetes, an increased hepatic fat content was found to be an important determinant of decreased hepatic insulin sensitivity [6,7]. Thiazolidinediones increase adiponectin gene expression and plasma levels [8,9]. In patients with type 2 diabetes, treatment with pioglitazone reduced visceral fat, hepatic fat content, and alanine aminotransferase (ALT) enzyme activity [7,10]. The decrease in hepatic fat and improvement in hepatic insulin sensitivity were closely associated with the increase in plasma adiponectin concentrations [7]. Moreover, treatment with recombinant adiponectin alleviated nonalcoholic steatohepatitis (NASH) in mice and pioglitazone treatment improved NASH in non-diabetic humans [11]. Patients with acromegaly and type 2 diabetes share many common features including insulin resistance, impaired glucose tolerance and increased incidence of macrovascular complications [12]. However, whereas visceral fat is increased in patients with type 2 diabetes, it is decreased in patients with acromegaly [6,13]. To the best of our knowledge, only one crosssectional study investigated adiponectin serum concentrations in patients with acromegaly [14]. Despite decreased insulin sensitivity in acromegalic subjects, adiponectin concentrations were found to be increased when compared to healthy controls. The aim of this study was to assess the effect of pituitary surgery in patients with acromegaly and the effect of pioglitazone therapy in patients with type 2 diabetes on insulin sensitivity, adiponectin serum concentrations, and ALT activity.
2. Materials and methods Sixteen consecutive patients with newly diagnosed acromegaly at the University Hospital of Zurich were included. Three acromegalic patients were excluded: one because of insulin-dependent diabetes mellitus, one because of an oesophageal cancer undergoing surgery and one because of a salmonella-induced coxitis. Diagnosis of acromegaly was established by clinical findings, elevated IGF 1 concentrations and
lack of growth hormone (GH) suppression to b1 Ag/L during an 75 g oral glucose tolerance test in all patients. MR imaging technique revealed pituitary macroadenomas (z10 mm in diameter) in 13 and microadenomas in 3 patients. All patients underwent transsphenoidal pituitary surgery as primary treatment. In addition, 16 patients with type 2 diabetes mellitus undergoing a therapy with pioglitazone were included. Exclusion criteria were insulin therapy, contraindications against pioglitazone, women without an effective contraception, and serious concomitant illness. From the 16 patients with type 2 diabetes included, 5 were on diet, 7 on metformin, 2 on repaglinide and 2 patients had a combination therapy of metformin and repaglinide. Therapy with pioglitazone 30 mg daily was started in all patients, the dose remained unchanged for 4 months. 2.1. Laboratory investigations All parameters were determined at baseline and at a mean follow-up period of 16–18 weeks following pituitary surgery or the start of pioglitazone therapy. All medications were discontinued the evening before the study, blood samples were drawn after an overnight fast. ALT enzyme activity was determined at the Institute for Clinical Chemistry of the University Hospital of Zurich on a Roche-Hitachi Modular Clinical Chemistry analyzer using commercial tests (with addition of pyridoxal phosphate) from Roche Diagnostics (Mannheim, Germany). Serum concentrations of adiponectin were measured using a commercially available sandwich enzyme-linked immunosorbent assay (ELISA) validated for serum and plasma (R&D Systems Europe, Abingdon, UK). The intra-assay coefficient of variation was 3.4% (at 69.9 ng/ml), the inter-assay coefficient 5.8% (at 74.4 ng/ml). For the determination of insulin-like growth factor 1 (IGF 1), carrier proteins were removed by Sep-PakR chromatography according to the instructions of the supplier (Waters Associates, Milford, MA) and IGF 1 was determined by radioimmunoassay (RIA) [15]. Acid-labile subunit (ALS) was measured using active total ALS ELISA, an enzymatically amplified btwo-stepQ sandwich-type immunoassay (Diagnostic Systems Laboratories, Webster, Texas, USA). Insulin was measured by a solid-phase RIA (CIS Bio international, Oris Industries, Gif-Sur-
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181
Yvette, France); normal overnight fasting range provided by the manufacturer was 30–138 pmol/L. Insulin resistance was estimated using homeostasis model assessment (HOMA) [16]. 2.2. Statistical analysis Data were presented as means and standard deviations (S.D.s) when not otherwise stated. Values before and after treatment within the two groups were analyzed using the Wilcoxon signed Rank test. Comparison between the groups of patients were evaluated by the Wilcoxon Rank sum test. A p-value b0.05 was considered statistically significant.
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Table 2 (A) Pre- and postoperative findings in 16 patients with acromegaly Preoperative Postoperative IGF-1 (Ag/L) 693F314 ALS (Ag/L) 30.1F10 Body weight (kg) 80.5F12.8 Waist circumference (cm) 94.4F6.5 Plasma glucose (mmol/L) 5.6F0.9 Insulin (pmol/L) 196F114 HOMA score 6.8F4 Triglycerides (mmol/L) 1.1F0.4 HDL-cholesterol (mmol/L) 1.5F0.3 ALT (U/L) 21F5 Adiponectin (mg/L) 9.3F3.8
255F91 17.2F7.4 79.8F13.1 95.8F8.5 5.1F1.1 113F36 3.5F0.9 0.8F0.3 1.6F0.2 17F9 10.2F4.4
p* pb0.005 pb0.005 ns ns pb0.05 pb0.005 pb0.005 pb0.05 ns pb0.05 pb0.05
(B) Findings in 16 patients with type 2 diabetes at baseline and after 4 months of therapy with pioglitazone 30 mg daily At baseline After 4 months p*
3. Results Baseline characteristics of all 32 patients are shown in Table 1. No significant differences were found between patients with acromegaly and type 2 diabetes concerning gender, duration of disease, BMI, body weight, fasting insulin concentration, HOMA score, triglycerides, HDL-cholesterol and ALT activity. Patients with type 2 diabetes were significantly older (61F9 years) compared to the patients with acromegaly (48F16 years). Waist circumference, plasma glucose and HbA1c were significantly higher in Table 1 Baseline characteristics
Sex (m/f) Age (years) Duration of disease (years) Weight (kg) BMI (kg/m2) Waist circumference (cm) Plasma glucose (mmol/L) Insulin (pmol/L) HOMA score HbA1c (%) Triglycerides (mmol/L) HDL-cholesterol (mmol/L) ALT (U/L) Adiponectin (mg/L)
Type 2 diabetes (n=16)
Acromegaly (n=16)
p*
12/4 61F9 6F5 83F11 29.7F4.5 103F8 8.6F2.6 140F58 7.6F4.3 7.4F0.9 1.4F0.8 1.4F0.4 26F19 6.1F3.5
8/8 48F16 6F4 81F13 27.1F3.5 94F7 5.6F0.9 196F114 6.8F4 6F0.8 1.1F0.4 1.5F0.3 21F5 9.3F3.8
ns pb0.05 ns ns ns pb0.005 pb0.005 p=0.08 ns pb0.005 ns ns ns pb0.005**
* By Wilcoxon Rank sum. ** Not statistically different when adjusted for age.
Body weight (kg) 83.4F11.2 84.8F11.7 Waist circumference (cm) 103.4F7.9 105.1F8.2 Plasma glucose (mmol/L) 8.6F2.6 7.8F1.6 HbA1c (%) 7.4F0.9 7F0.5 Insulin (pmol/L) 139F58 114F42 HOMA score 7.6F4.3 5.4F2.1 Triglycerides (mmol/L) 1.4F0.8 1.4F0.8 HDL-cholesterol (mmol/L) 1.4F.0.4 1.4F0.3 ALT (U/L) 26F19 20F10 Adiponectin (mg/L) 6.1F3.4 11.5F4.9
pb0.05 pb0.05 pb0.05 p=0.06 pb0.05 pb0.05 ns ns pb0.05 pb0.005
* By Wilcoxon Signed Rank test.
patients with type 2 diabetes compared to patients with acromegaly. Baseline adiponectin concentrations were 6.1F3.5 mg/L in patients with type 2 diabetes, i.e., lower than in acromegalic patients (9.3F3.8 mg/L). This difference was no more significant when adiponectin levels were adjusted for age ( p=0.053). Findings in patients with type 2 diabetes undergoing treatment with pioglitazone are illustrated in Table 2. In patients with type 2 diabetes treated with pioglitazone, body weight increased from 83.4F11.2 to 84.8F11.7 kg ( pb0.05) and waist circumference from 103 to 105 cm ( pb0.05). Fasting plasma glucose concentration decreased from 8.6F2.6 to 7.8F1.6 mmol/L ( pb0.05) and HbA1c from 7.4F0.9 to 7F0.5% ( p=0.06). In the same period, fasting insulin concentrations decreased from 139F58 to 114F42 pmol/L ( pb0.05). Triglycerides and HDL-cholesterol concentrations remained unchanged, but ALT activity decreased from median 20 (range 14–86) to 17 (9–46) U/L ( pb0.05; mean FSD in Table 2).
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Pre- and postoperative findings in acromegalic patients are shown in Table 2. Transsphenoidal surgery resulted in effective tumor debulking as documented by at least partial decreases in disease activity and IGF 1 serum concentrations. IGF 1 concentrations decreased from 693F314 to 255F91 Ag/L ( pb0.005). Ten patients (63%) were cured as defined by clinical and biochemical criteria, i.e., both normal age-adjusted IGF
1 serum concentration and GH suppressed to b1 ng/ml during the oral glucose tolerance test, an often cited definition of cure in patients with acromegaly [17]. ALS decreased in each individual patient, from 30.1F10 to 17.2F7.4 mg/L ( pb0.005). Body weight and waist circumference did not significantly change following neurosurgery (as assessed 4 months later). Improved insulin sensitivity was indicated by signifi-
Fig. 1. HOMA and adiponectin serum concentrations in 16 patients with type 2 diabetes at baseline and following treatment with pioglitazone and in 16 patients with acromegaly at baseline and following pituitary surgery.
P. Wiesli et al. / Clinica Chimica Acta 352 (2005) 175–181
cant decreases in plasma glucose and serum insulin concentrations, as well as in the HOMA scores. In the same period, ALT activity decreased from median 21 (13–30) to 13 (10–42) U/L ( pb0.05; mean F SD in Table 2), and triglyceride concentrations fell from 1.1F0.4 to 0.8F0.3 mmol/L ( pb0.05). HOMA scores and adiponectin concentrations of each individual patient are shown in the figure. HOMA scores decreased in both groups of patients, indicating improved insulin sensitivity in patients with type 2 diabetes following treatment with pioglitazone as well as in acromegalic patients following pituitary surgery. In patients with type 2 diabetes treated with pioglitazone, HOMA scores decreased from 7.6F4.3 to 5.4F2.1 ( pb0.05). In the same period, adiponectin concentrations increased markedly, from 6.1F3.4 to 11.5F4.9 mg/L ( pb0.005). As shown in Fig. 1, adiponectin concentrations increased in each individual patient. In patients with acromegaly, HOMA score dropped from 6.8F4 at baseline to 3.5F0.9 ( pb0.005) following pituitary surgery. In the same period, adiponectin concentrations increased slightly but significantly from 9.3F3.8 to 10.2F4.4 mg/L ( pb0.05). Adiponectin concentrations increased in 13 of 16 (81%) patients.
4. Discussion Our data confirm that thiazolidinedione drugs increase circulating adiponectin concentrations and improve insulin sensitivity in patients with type 2 diabetes, as illustrated by the drop of HOMA scores [18]. Although we did not measure body composition and visceral fat in our study, the increase in waist circumference following pioglitazone therapy might be assigned to an increase in subcutaneous rather than visceral fat because the latter usually decreases [18]. In a previous study, pioglitazone treatment reduced hepatic fat content and decreased ALT enzyme activity; the latter observation is confirmed by our data [7]. Thus, the increase in adiponectin concentrations and the decrease in ALT activity following pioglitazone therapy in patients with type 2 diabetes may be related to improved insulin sensitivity and a decrease in hepatic fat content. In contrast to patients with type 2 diabetes, patients with untreated acromegaly have decreased visceral fat
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[19]. In our study, waist circumference was significantly lower in patients with acromegaly than in diabetic subjects. Despite comparably impaired insulin sensitivity and statistically not different body weight, baseline adiponectin concentrations in patients with acromegaly were higher than in diabetic subjects. This difference in adiponectin concentrations was observed irrespective of the gender of the patients (higher levels have been reported in women) [20] but was not statistically significant when adiponectin levels were adjusted for age. A previous study showed higher adiponectin concentrations in patients with acromegaly compared to weight-matched healthy controls [14]. Herein, we describe for the first time the change of adiponectin serum concentrations in patients with acromegaly undergoing pituitary surgery. The efficacy of tumour debulking was illustrated by the drop of the GH-dependent serum proteins IGF 1 and ALS. The former (IGF 1) is predominantly and the latter (ALS) is exclusively produced by hepatocytes. Following surgery, we found a modest but significant increase in adiponectin concentrations in 13 of 16 patients. This finding was in parallel with the improved insulin sensitivity (correlation was not statistically significant). However, whereas improvement of insulin sensitivity following pituitary surgery was definite, increase in adiponectin was only modest. Apparently, parameters potentially affecting adiponectin concentrations (insulin sensitivity and visceral fat) counteract each other in acromegalic subjects. As indicated above, the increased insulin sensitivity following pituitary surgery occurred in a condition where fat mass is initially low. Within 4 months following surgery, visceral fat may not be restored to normal, a fact which may account for an attenuated rise in adiponectin concentrations despite markedly increased insulin sensitivity [13]. However, visceral fat or body composition were not measured in our study. In recent studies, treatment with GH in GHdeficient patients had no effect on circulating adiponectin concentrations. In one study, no significant change in adiponectin was observed despite a reduction in fat mass and a decrease in insulin sensitivity following GH therapy [21]. Another study confirmed that the change in body composition in GH-deficient patients treated with GH was not associated with a change in circulating adiponectin concentrations [22]. In that study, insulin sensitivity was not significantly
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altered by GH therapy. Thus, adiponectin concentrations of patients with GH deficiency and excess, respectively, seem to be regulated in a complex manner warranting further studies. Interestingly, the increase of adiponectin following pituitary surgery was associated with a modest but significant decrease of ALT enzyme activity within the normal range. A relevant limitation of our study is that we did not measure hepatic fat content. Thus, we cannot conclude whether this decrease in ALT activity reflects a decrease in intrahepatic fat content. To the best of our knowledge, no data exist concerning the hepatic fat content in acromegalic patients. Whether a specific pathophysiological condition in acromegalic patients undergoing pituitary surgery (i.e., inflammation, reduced hepatic fat, decrease in GH excess, etc.) is responsible for the postoperative decrease in ALT activity cannot be derived from our data. Because the determination of the enzyme activity was performed with the addition pyridoxal phosphate, a transient postoperative vitamin B6 deficiency interfering with the determination of ALT can be ruled out [23]. Longterm administration of adiponectin improved insulin sensitivity and decreased liver, muscle and plasma triglycerides in diabetic mice [24,25]. In our study, the modest increase in adiponectin in acromegalic patients undergoing pituitary surgery was associated with improved insulin sensitivity as well as a decrease in ALT activity and plasma triglyceride concentrations. However, whether the change in adiponectin serum concentration was causal for the liver functionrelated changes observed cannot be derived from our data. In conclusion, we have demonstrated that pituitary surgery in patients with acromegaly led to a marked increase in insulin sensitivity and a slight but significant increase in adiponectin serum concentrations, ALT enzyme activity significantly decreased over the same period. References [1] Berg AH, Combs TP, Du X, Brownlee M, Scherer PE. The adipocyte-secreted protein Acrp30 enhances hepatic insulin action. Nat Med 2001;7:947 – 53. [2] Yamauchi T, Kamon J, Ito Y, Tsuchida A, Yokomizo T, Kita S, et al. Cloning of adiponectin receptors that mediate antidiabetic metabolic effects. Nature 2003;423:762 – 9.
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