Responses of luteinizing hormone, follicle-stimulating hormone, and prolactin to prolonged administration of a dopamine antagonist in normal women and women with low-weight amenorrhea

FERTILITY AND STERILITY Copyright e 1981 The American Fertility Society

Vol. 35, No.6, June 1981 Printed in U.8A.

RESPONSES OF LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, AND PROLACTIN TO PROLONGED ADMINISTRATION OF A DOPAMINE ANTAGONIST IN NORMAL WOMEN AND WOMEN WITH LOW-WEIGHT AMENORRHEA

STEEN LARSEN, M.D.*

Institute of Gynaecology and Obstetrics, Odense University Hospital, Odense, Denmark

The responses of luteinizing hormone, follicle-stimulating hormone, and prolactin to prolonged administration of the dopamine receptor antagonist metoclopramide (5 mg twice daily) were investigated in six normal women and six women with lowweight amenorrhea (LWA). In contrast to the normal group, the LWA group showed no significant changes in the mean basal prolactin level or the mean prolactin response to stimulation with thyrotropin-releasing hormone, but there was a significant elevation of the mean net increase in luteinizing hormone after stimulation with gonadotropin-releasing hormone. On the basis of these data, the possibility of increased central dopaminergic activity in women with L WA is discussed. Fertil Steril 35:642,1981

Women in the recovery stages of anorexia nervosa and women with low-weight amenorrhea (L WA) seem to share the same hypothalamic dysfunction. I -3 It has been suggested that increased activity of dopamine (DA) at central DA receptors plays a role in this dysfunction. 4 For instance, the proposed decreased secretion and/or production of gonadotropin-releasing hormone (GnRH)2, 5, 6 could be explained in this way according to animal studies. 7 Although normal serum prolactin (PRL) levels have been found in women with LWA,2, 3, 8 the lowest PRL levels in this clinic have been found among women with this condition, again lending support to the theory of increased central DA activity.9 In an attempt to elucidate this possibility, a DA receptor antagonist, metoclopramide (MTC),10-12 was given for 4 weeks to women with LWA and to women with normal cycles, and the responses of luteinizing hormone (LH), folliclestimulating hormone (FSH), and PRL were investigated.

PATIENTS AND METHODS

Six women with LWA after severe, self-imposed loss of weight, and six normal women with proven fertility volunteered for the study. Clinical and hormonal data are presented in Tables 1 to 3. In all LWA patients the androsterone/etiocholanolone ratio, determined in 24-hour urine, was below the lower limit (2 SD) of levels of normal women of the same age. Serum testosterone levels were normal. Following clomiphene citrate administration in daily doses of 150 mg to 250 mg for 5 days, all of the LWA patients had scanty menstrual bleeding but no signs of ovulation as judged by basal body temperature monitoring. While the women were fasting, a combined test with GnRH (LRF, Roche A/S, Hvidovre, Denmark) and thyrotropin-releasing hormone (TRH) (Protirelinum, Roche A/S) was performed before and after administration of MTC (Primperan, Lundbeck A/S, Valby, Denmark), 5 mg twice daily for 4 weeks. GnRH (50 j.Lg) and TRH (200 j.Lg) were given intravenously as a bolus injection at time zero. Blood samples were obtained through an indv. <.oIling venous catheter at time -10, 0, 20, 30, and 60 minutes.

Received November 24, 1980; revised and accepted February 3, 1981. *Reprint requests: Steen Larsen, M.D., Institute of Gynaecology and Obstetrics, Odense University Hospital, 5000 Odense C, Denmark.

642

r

I

LH, FSH, AND PROLACTIN IN LOW·WEIGHT AMENORRHEA

Vol. 35, No.6

643

,

TABLE 1. Clinical Data for Six Women with LWA and Six Normal Cycling Women with Proven Fertility Group

LWA Mean Range Normal Mean Range

Age at menarche

Highest wt. before amen~ orrhea

Wt. at start of amenorrhea

Lowest wt.

Duration of amenorrhea

Age at in· vestigation

Wt. at in· vestigation

yr

%ABW"

%ABW

%ABW

yr

yr

%ABW

13.7 12-17

105.6 102.3-108.1

88.8 80.8-93.2

75.1 65.2--87.2

10.7 6---14

28.3 24-31

90.3 b 76.1-107.9

28.0 25-31

100.8 93.4-115.1

13.0 11-15

aABW, average body weight, Documenta Geigy, Scientific Tables, Sixth edition, page 623. bp < 0.05 versus the normal group.

In the six normal women the first test was performed during the early follicular phase (day 4 to day 6), and the second test on the corresponding day of the following cycle after 4 weeks of MTC administration. The latest MTC dose was given approximately 10 hours before the test in both groups. Serum concentrations of LH, FSH (milli-international units of Second International Reference Preparation), and 17~-estradiol (picograms per milliliter) were determined by radioimmunoassays at the State Serum Institute in Copenhagen,

Denmark. Serum PRL levels (nanograms per milliliter, VLS no. 1) were determined by radioimmunoassay at the Department of Clinical Chemistry, Odense University Hospital. RESULTS

The hormone values before (A) and during administration of MTC (B) were compared by using Student's t-test for paired data. To obtain a close approximation to a normal distribution, the hormone values were transformed into logarithms,

TABLE 2. Basal Values and Responses to a Combined GnRH/TRH Test Before (A) and During Chronic Administration of Metoclopramide (B) in Six Normal Cycling Women in the Early Follicular Phase Hormonea

Time

Treat· ment

Nonnal subject 2

3

4

5

6

11.5 5.5 16.5 8.5 17.5 10.5 17.5 8.5 26.5 19.0 6.5 3.0 11.5 7.0 6.5 7.0 3.0 34.5 57.0 81.6 53.0 78.0 29.8 44.2 21 55

7.5 9.0 25.5 26.0 25.5 25.0 13.5 12.0 19.5 17.5 14.5 13.5 19.5 12.5 7.5 13.5 2.6 7.9 40.5 108.1 35.9 84.1 13.5 34.3 35 20

7.0 7.0 9.0 15.0 13.0 19.0 10.0 14.0 20.5 27.0 4.5 4.0 6.5 10.0 8.5 8.0 6.4 30.4 53.5 68.4 52.3 58.0 28.1 19.9 49 37

5.5 10.0 14.5 15.0 15.5 14.0 9.5 8.0 22.0 15.5 6.0 8.5 8.0 9.5 7.0 7.5 3.3 14.8 15.2 38.6 13.3 35.3 3.6 11.5 36 38

6.0 6.0 21.0 29.0 19.0 31.0 11.0 19.0 23.0 21.5 11.0 13.5 11.0 14.5 9.0 10.5 3.4 25.8 30.2 62.3 27.3 52.1 13.0 16.3 42 44

Geometric mean (B:A)

d{

t Value b

0.95

5

-0.2639 c

1.05

5

0.2872 c

1.05

5

0.3341c

0.97

5

-0.1875 c

0.89

5

-1.2653 c

0.90

5

-0.6497 c

0.94

5

-0.3709 c

1.04

5

0.2380 c

5.00

5

7.2537 d

2.09

5

4.8708 d

1.94

5

4.5161 d

1.78

5

2.3955 C

min

Basal LH (mIU/mll Net increase

20

Net increase

30

Net increase

60

Basal FSH (mIU/mll Net increase

0 20

Net increase

30

Net increase

60

Basal PRL (ng/mll Net increase

0 20

Net increase

30

Net increase

60

Basal 17J3-estradiol (pg/mll

0

0

A B A B A B A B A B A B A B A B A B A B A B A B A B

7.0 5.0 17.0 18.0 17.0 18.0 14.0 13.0 26.5 23.5 10.5 8.5 11.5 8.5 15.5 8.5 7.5 20.8 15.0 49.5 13.5 37.2 5.2 15.5 47 46

aBasal values are the means of two samples. Net increase at a given time is the value measured minus the basal value. bTesting if the geometric mean of ratio (B:A) differs from 1.0. cp> 0.05. dp < 0.05.

r LARSEN

644

June 1981

TABLE 3. Basal Values and Responses to a Combined GnRH/TRH Test Before (A) and During Chronic Administration of Metoclopramide (B) in Six Women with LWA Hormoneu

Time

Treat· ment

Patient

Geometric mean

2

3

4

5

6

5.0 11.5 11.0 45.5 12.0 47.5 10.0 39.5 27.0 21.0 4.0 11.0 6.0 16.0 5.0 19.0 2.4 3.9 12.5 10.3 14.2 11.8 7.5 4.2 49 37

2.0 2.0 17.0 24.0 17.0 23.0 15.0 21.0 11.0 21.5 13.0 13.5 19.0 25.5 20.0 30.5 6.9 3.5 83.7 21.4 53.4 22.7 36.0 14.8 <10 <10

2.0 2.0 8.0 27.0 11.0 29.0 10.0 28.0 15.5 18.5 8.5 12.5 15.5 29.5 15.5 29.5 4.1 6.2 12.5 26.6 15.9 19.0 10.7 14.1 <10 <10

2.0 2.0 26.0 29.0 27.0 31.0 21.0 23.0 20.0 14.5 42.0 35.5 49.0 46.5 56.0 42.5 2.2 19.0 27.0 40.4 21.6 27.8 12.2 10.9 50 50

8.0 9.5 25.0 30.5 27.0 30.5 25.0 27.5 23.5 20.5 22.5 14.5 24.5 17.5 29.5 17.5 4.1 59.0 37.1 60.7 30.8 48.0 21.0 14.5 62 61

df

t Value b

1.15

5

0.9676c

1.98

5

3.0359 d

1.80

5

2.8557 d

1.83

5

2.8244d

0.96

5

-0.2544c

1.34

5

1.2111c

1.39

5

1.6860c

1.40

5

1.2439c

2.21

5

1.4480c

0.95

5

-0.1690c

0.89

5

-0.5476c

0.69

5

-2.2470c

(B:A)

min

Basal LH (mID/ml) Net increase

0 20

Net increase

30

Net increase

60

Basal FSH (mID/ml) Net increase

0 20

Net increase

30

Net increase

60

Basal PRL (ng/ml) Net increase

0 20

Net increase

30

Net increase

60

Basal 17f3-estradiol (pg/ml)

0

A B A B A B A B A B A B A B A B A B A B A B A B A B

10.0 8.5 29.0 65.5 30.0 55.5 21.0 42.5 28.0 19.0 10.0 25.0 15.0 23.0 15.0 23.0 4.3 3.2 72.4 47.8 67.6 41.0 35.8 20.0 52 56

aBasal values are the means of two samples. Net increase at a given time is the value measured minus the basal value. bTesting if the geometric mean of ratio (B:A) differs from 1.0. cp> 0.05. dp< 0.05.

thus calculating the mean of log m:A). The antilog of this statistic-or the geometric mean-is shown in Tables 2 and 3. The mean basal levels of LH, FSH, and PRL and the mean responses to GnRH/TRH were equal in the two groups (unpaired Student's ttest) before MTC was given (Fig. 1). In the six normal women (Table 2), administration of MTC did not change the mean basal level or the mean response of LH or FSH, whereas the mean basal level of PRL was significantly higher (400%) during MTC administration, as was the net increase at 20 minutes (109%) and at 30 minutes (94%). In the six women with LWA (Table 3), the mean basal level of LH remained unchanged, whereas the mean net increase at 20 minutes was significantly higher (98%) during administration of MTC, as was the mean net increase at 30 minutes (80%) and at 60 minutes (83%). The mean basal levels and the mean responses to FSH and PRL were not significantly affected by MTC administration. Mean values before and during metoclopramide and differences between the two groups are seen in Figure 1.

In both groups the basal levels of serum 17(3estradiol remained unchanged. Two to four weeks after the second GnRH/TRH test, during the administration of MTC, a trial with clomiphene citrate in patients 1, 2,3, and 4 resulted in the same response as before, with no signs of ovulation. The well-being of the participating women was unaffected by MTC administration. DISCUSSION

It is believed that DA is released from tuberoinfundibular neurons in the median eminence and is bound to specific receptors on the lactotrophs in the anterior pituitary gland to inhibit PRL release. 13 , 14 PRL also regulates, in part, its own secretion by a short-loop feedback action on the same neurons in the median eminence, enhancing the DA secretion. 15 , 16 Although it is controversial,17 increased DA activity in this region is believed to suppress the release of GnRH.7, 15 If these mechanisms were operative in women, the consequences of increased central DA activity would be diminished LH and PRL secretion. The

LH, FSH, AND PROLACTIN IN LOW-WEIGHT AMENORRHEA

Vol. 35, No.6 80 70 60 50 40 30 20 10 0 90 80 70 60 50 40 30 20 10

o •

Normal women LWA

LH

~~~~

PRL

FSH

~J~J

~~~~ •

•

• •

~~~j 0203060

• •

~JJJ 0203060

fu

20

30

~ 60

FIG. 1. Mean basal values and mean responses to a combined GnRHlTRH test before (upper bars) and during chronic administration of metoclopramide (lower bars) in six normal women (open bars) and six women with low-weight amenorrhea (closed bars). Basal values (0 minutes) and net increases at 20, 30, and 60 minutes of LH (milli-international units per milliliter), FSH (milli-international units per milliliter), and PRL (nanograms per milliliter) are geometric means ± standard errors. Asterisks P < 0.05 to P < 0.001.

DA receptor antagonist MTC in this isolated system could (1) modulate the gonadotropic secretion by a direct action on the anterior pituitary_ This was not the case in acute studies,18 and a DA receptor has not been found on the gonadotrophs (see reference 19 for citations, and reference 14). MTC could (2) competitively inhibit the action of DA on DA receptors on the lactotrophs, thus increasing PRL secretion; (3) inhibit the inhibiting action of DA on GnRH release by blocking a probably existing19 DA receptor in the median eminence, thus increasing GnRH secretion; and (4) enhance the central DA activity indirectly through the increased PRL secretion. As this fourth possible action of MTC would complicate the evaluation of the results of this investigation, an MTC dose was chosen which is submaximal in relation to PRL release. 12 In this study the prolonged administration of MTC did not influence the lev~ls of 1713-estradiol in the normal group or the LWA group on the days of testing. Most likely the steroid milieu had not changed throughout the experiment in the LWA group, whereas it had been fluctuating in the normal group, probably modulating the response to both MTC and the GnRH/TRH test. The significant elevation of both the mean basal PRL level and the mean response to TRH in the normal group during MTC administration indi-

645

cates that MTC, at the dose used and during the time of the study, was effective as a DA antagonist. In contrast, the mean basal PRL level and the response to TRH during MTC administration in the LWA group was unchanged_ This could indicate increased central DA activity and DA release, competing with MTC for DA receptors. This possibility is supported by a recent paper by Quigley and colleagues,18 who, in studying an LWA group, found low basal PRL levels and a reduced PRL response to an acute intravenous injection of MTC. There is no reason to believe that the central DA activity is low in LWA, since the mean basal pretreatment levels of PRL were equal in the two groups of this study. In the normal group, MTC administration induced no changes in the mean basal LH or FSH levels or the responses to GnRH, whereas in the LWA group the mean LH response to GnRH was significantly increased. Again this could indicate increased central DA activity at DA receptors in LWA, which during MTC administration is partially inhibited, resulting in a release of GnRH in an amount large enough to promote priming, but too small to favor release of LH.20 Although the changes in PRL and LH levels during MTC administration could be taken into account for the theory of increased central DA activity in LWA, the patients remained amenorrheic during the 6 to 8 weeks MTC was given, and a trial with clomiphene citrate in four of the women did not induce ovulation, which indicates that the positive feedback effect of estradiol was still lacking. REFERENCES 1. Warren MP, Jewelewicz R, Dyrenfurth I, Ans R, KhalafS, Vande Wiele RL: The significance of weight loss in the evaluation of pituitary response to LH-RH in women with secondary amenorrhea. J Clin Endocrinol Metab 40:601, 1975 2. Vigersky RA, Loriaux DL: Anorexia nervosa as a model of hypothalamic dysfunction. In Anorexia Nervosa, Edited by RA Vigersky. New York, Raven Press, 1977, p 109 3. Knuth UA, Hull MGR, Jacobs HS: Amenorrhoea and loss of weight. Br J Obstet Gynaecol 84:801, 1977 4. Barry CV, Klawans HL: On the role of dopamine in the pathophysiology of anorexia nervosa. J Neural Transm 38:107, 1976 5. Yoshimoto Y, Moridera K, Imura H: Restoration of normal pituitary gonadotropin reserve by administration of luteinizing-hormone-releasing hormone in patients with hypogonadotropic hypogonadism. N Engl J Med 292:242, 1975

r

646

LARSEN

6. Nillius SJ, Wide L: The pituitary responsiveness to acute and chronic administration of gonadotropin-releasing hormone in acute and recovery stages of anorexia nervosa. In Anorexia Nervosa, Edited by RA Vigersky. New York, Raven Press, 1977, p 225 7. Fuxe K, Hokfelt T, Agnati L, Lofstrom A, Everitt BJ, Johansson 0, Jonsson G, Wuttke W, Goldstein M: Role of monoamines in the control of gonadotrophin secretion. In Neuroendocrine Regulation of Fertility: International Symposium Simla. Basel, Karger, 1976, p 124 8. Isaacs AJ, Leslie RDG, Gomez J, Bayliss R: The.effect of weight gain on gonadotrophins and prolactin in anorexia nervosa. Acta Endocrinol (Kbh) 94:145, 1980 9. MacLeod RM: Regulation of prolactin secretion. In Frontiers in Neuroendocrinology, Vol 4, Edited by L Martini, WF Ganong. New York, Raven Press, 1976, p 169 10. McCallum RW, Sowers JR, Hershman JM, Sturdevant RAL: Metoclopramide stimulates prolactin secretion in man. J Clin Endocrinol Metab 42:1148, 1976 11. Jenner P, Clow A, Reavill C, Theoderou A, Marsden CD: A behavioural and biochemical comparison of dopamine receptor blockade produced by haloperidol with that produced by substitute benzamide drugs. Life Sci 23:545, 1978 12. Healy DL, Burger HG: Increased prolactin and thyrotrophin secretion following oral metoclopramide: doseresponse relationships. Clin Endocrinol (Oxf) 7:195, 1977 13. Ben-Jonathan N: Catecholamines and pituitary prolactin release. J Reprod Fertil 58:501, 1980

June 1981 14. Nansel DD, Gudelsky GA, Porter JC: Subcellular localization of dopamine in the anterior pituitary gland of the rat: apparent association of dopamine with prolactin secretory granUles. Endocrinology 105:1073, 1979 15. Gudelsky GA, Simpkins J, Mueller GP, Meites J, Moore KE: Selective actions of prolactin on catecholamine turnover in the hypothalamus and on serum LH and FSH. Neuroendocrinology 22:206, 1976 16. Gudelsky GA, PorterJ: Release of dopamine from tuberoinfundibular neurons .into pituitary stalk blood after prolactin or haloperidol administration. Endocrinology 106:526, 1980 17. Negro-Vilar A, Ojeda SR, McCann SM: Catecholaminergic modulation of luteinizing hormone-releasing hormone release by median eminence terminals in vitro. Endocrinology 104: 1749, 1979 18. Quigley ME, Sheehan KL, Casper RF, Yen SSC: Evidence for increased dopaminergic and opioid activity in patients with hypothalamic hypogonadotropic amenorrhea. J Clin Endocrinol Metab 50:949, 1980 19. Cronin MJ, Roberts JM, Weiner RI: Dopamine and dihydroergocryptine binding to the anterior pituitary and other brain areas of the rat and sheep. Endocrinology 103:302, 1978 20. Hoff JD, Lasley BL, Yen SSC: The functional relationship between priming and releasing actions of luteinizing hormone-releasing hormone. J Clin Endocrinol Metab 49:8,1979