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Long-term adrenergic β-action decreases and α-action enhances Corticosterone levels in rats
Exp. Pathol. 31, 59-61 (1987) VEB Gustav Fischer Verlag Jena University of Graz, Austria: 1) Institute of Functional Pathology; 2) Department of Pediatrics
Long-term adrenergic {J -action decreases and IX-action enhances Corticosterone levels in rats
With one Figure
Address for correspondence: Univ.-Dozent Dr. SEPP PORTA, Institut fiir Funktionelle Pathologie, Mozartgasse 14/11, A - 8010 Graz, Austria Key words: adrenergic actions, long-term; Corticosterone; ACTH-glucocorticoid system; adrenaline (A)- and blocker application; propranolol (Prop)
Summary A 20 h hyperadrenalinemia in rats was produced by subcutaneously implanted A-retard tablets with an output rate of 1.8 pg/min/250 g. This caused a moderate (6 h, 20 h) to expressed (12 h) rise in Corticosterone. Concomitant {J-blockade leads to equal (12 h, 20 h) or even more expressed (6 h) enhancement of plasma corticosterone, while A + IX-blockade lowers those levels significantly against A or A + Prop treated animals. At 6 and 20 h they are even significantly lower than control values. We therefore conclude that enhanced IXadrenergic influence increases and {J-adrenergic influence decreases plasma Corticosterone levels in rats.
Introduction Systemic adrenergic stimulation influences the ACTH - Glucocorticoid system (NAKAI et ai. 1973; GIGUERE et ai. 1981, 1983). Previous papers either did not discern whether this is mediated through IX- or {J-action, or if they did, the results are controversial (TILDERS et ai. 1982; TIMMERMANS et ai. 1980). Using long term release system for adrenaline- and blocker-application we tried to throw some light on that problem. As we used rats we investigated Corticosterone, their main glucocorticoid.
Materials and Methods Four groups of male Sprague Dawley OFA (ONCINS-France A, Himberg) rats were treated as follows: First group, controls (C), was fitted with a subcutaneously implanted placebo tablet and with an also subcutaneously implanted depot capsule, containing 1.9 ml of physiological saline. Second group, Adrenaline (A)-group, received an A containing retard tablet (output rate 1.8 p,g/ min/250 g) and a depot capsule, containing physiological saline (PORTA et al. 1984). The third group, A + Regitine (Reg) group, was treated with the A-retard tablet and a depot capsule containing 3 mg/ml Reg (output rate 2.51 p,g/min/250 g). The fourth group, A + Propranolol (Prop) group, was again fitted with an A-retard tablet and a depot capsule containing 3 mg/ml Prop (output rate 2.52 p,g/min/250 g). 6,12 and 20 h after implantation several animals (number see table) out of each group were carefully sacrificed (SADJAK et al. 1983), generally at 9 a.m., to prevent differences in Corticosteronelevels due to circadian rhythm. Serum Corticosterone levels (RIA) and plasma catecholamine levels (REA) were measured. t-tests and standard error of mean were calculated with an OLIVETTI P 6040 Computer).
59
cormcoSTErlONE PLASMA LEVELS Corticosterone IJg/l
AOrlENALINE IA) 0 A+ PrlOPMNOLOL 0 un A+rlEGITINE
600
1]=====c 200
hrs
12 Fig. 1.
Results Plasma A-levels are enhanced against controls in all of the three test groups, whereby the A except at 12 h and A + Prop group show slightly lower levels than the A + Reg group (table 1: free plasma A-levels). Adrenaline treatment alone causes general enhancement of Corticosterone levels against controls which is highly significant (p < 0.01) after 12 h (fig. 1: Corticosterone plasma levels). In spite of the highest A levels, Corticosterone concentrations in plasma of the A + Reg group are even lower than controls after 6 and 20 h (fig. 1). Compared to the A + Prop group they are always significantly lower (fig. 1). Corticosterone levels of the A + Prop group are significantly higher than controls after 6 and 12 h. Adrenaline + Prop treatment leads to an earlier peak and also earlier decline of Corticosterone than A-treatment alone. Table 1. Free plasma adrenaline-levels
+ Prop
+ Reg
Hours
C
A
6 12 20
4.099 ± 0.511 3.704 ± 0.585 3.901 ± 0.453
6.625 ± 3.1:26 6.19 ± 1.545 15.176 ± 5.074 7.194 ± 1.664 7.;353 ± :2.162 6.:2:27 ± 1.159
12.401 ± 1.889 7.972 ± 1.002 13.912 ± 2.863
n
24
36
44
A
.til
A
X ± SEM X± SEM X ± SEM
Discussion Therefore we conclude that adrenergic LX-action enhances and fl-action suppresses Corticosterone serum levels. This is partly supported by SHIMIZU (1984) who found depressed ACTH-Ievels during simultaneous treatment with A and LX-blockers, which suggests LX-catecholaminergic effects operating via CRH - the last common step of nearly all ACTH-touching stimuli except vasopressin - ACTH and Corticosterone. On the other hand we could show enhancement of Corticosterone in animals treated 6 h with A + Prop against the A treated group. SHIMIZl did not observe increase in ACTH-levels during increased LX-action. This could either be due to the fact that ours was a long-term test, or to direct or indirect LX-influence~ on Corticosterone production which do not act via ACTH.
60
Exp. Pathol. 31 (1987) 1
Literature GIGUERE, V., J. COTE and F. LABRI, Characteristics of the alia-adrenergic stimulation of adrenocorticotropin secretion in rat anterior pituitary cells. Endocrinology 109, 757-762 (1981). - and F. LABRI, Additive effects of epinephrine and corticotropin-releasing factor (CRF) on adrenocroticotropin release in rat anterior pituitary cells. Biochem. Biophys. Res. Commun. 110, 456 to
462 (1983).
NAKAI, Y., H. IMURA, T. YOSHIMI, S. MATSUKURA, Adrenergic control mechanism for ACTH secretion in man. Acta Endocrinol. 74, 263-270 (1973). PORTA, S., A. SADJAK, S. SUPANZ, P. PURSTNER, W. KORSATKO, B. WABNEGG and U. ERTL, Peculiar long-term effects of catecholamines and their blockers in rats on insulin, glucose and pancreas. Exp. Pathol. 26, 241-245 (1984). SADJAK, A., H. G. KLINGENBERG, G. EGGER and S. SUPANZ, Evaluation of the effects of blood smelling, handling and anesthesia on plasma catecholamines in rats. Z. Versuchstierkd. 20, (5), (1983). SHIMIZU, K., Effect of alfa1 and alfa2-adrenoceptor agonists and antagonist on ACTH secretion in intact and in hypothalamic deafferentated rats. Japan. J. Pharmacol. 36, 23-33 (1984). TILDERS, F. J. H., F. BERKENBOSCH, F. P. G. and SMELlK, Adrenergic mechanism involved in the control of pituitary-adrenal activity in the rat: a p-adrenergic stimulatory mechanism. Endocrinology 110, 114-120 (1982). TIMMERMANS, P. B. M. W. M., and P. A. VAN ZWIETEN, Postsynaptic alia!" and alfa2-adrenoceptors in the circulatory system of the pithed rat: selective stimulation of the alfa 2-type by B-HT 933. Eur. J. Pharmacol. 63 199-202 (1980). (Received January 22, 1986)
Exp. Pathol. 31 (1987) 1
61
Long-term adrenergic {J -action decreases and IX-action enhances Corticosterone levels in rats
With one Figure
Address for correspondence: Univ.-Dozent Dr. SEPP PORTA, Institut fiir Funktionelle Pathologie, Mozartgasse 14/11, A - 8010 Graz, Austria Key words: adrenergic actions, long-term; Corticosterone; ACTH-glucocorticoid system; adrenaline (A)- and blocker application; propranolol (Prop)
Summary A 20 h hyperadrenalinemia in rats was produced by subcutaneously implanted A-retard tablets with an output rate of 1.8 pg/min/250 g. This caused a moderate (6 h, 20 h) to expressed (12 h) rise in Corticosterone. Concomitant {J-blockade leads to equal (12 h, 20 h) or even more expressed (6 h) enhancement of plasma corticosterone, while A + IX-blockade lowers those levels significantly against A or A + Prop treated animals. At 6 and 20 h they are even significantly lower than control values. We therefore conclude that enhanced IXadrenergic influence increases and {J-adrenergic influence decreases plasma Corticosterone levels in rats.
Introduction Systemic adrenergic stimulation influences the ACTH - Glucocorticoid system (NAKAI et ai. 1973; GIGUERE et ai. 1981, 1983). Previous papers either did not discern whether this is mediated through IX- or {J-action, or if they did, the results are controversial (TILDERS et ai. 1982; TIMMERMANS et ai. 1980). Using long term release system for adrenaline- and blocker-application we tried to throw some light on that problem. As we used rats we investigated Corticosterone, their main glucocorticoid.
Materials and Methods Four groups of male Sprague Dawley OFA (ONCINS-France A, Himberg) rats were treated as follows: First group, controls (C), was fitted with a subcutaneously implanted placebo tablet and with an also subcutaneously implanted depot capsule, containing 1.9 ml of physiological saline. Second group, Adrenaline (A)-group, received an A containing retard tablet (output rate 1.8 p,g/ min/250 g) and a depot capsule, containing physiological saline (PORTA et al. 1984). The third group, A + Regitine (Reg) group, was treated with the A-retard tablet and a depot capsule containing 3 mg/ml Reg (output rate 2.51 p,g/min/250 g). The fourth group, A + Propranolol (Prop) group, was again fitted with an A-retard tablet and a depot capsule containing 3 mg/ml Prop (output rate 2.52 p,g/min/250 g). 6,12 and 20 h after implantation several animals (number see table) out of each group were carefully sacrificed (SADJAK et al. 1983), generally at 9 a.m., to prevent differences in Corticosteronelevels due to circadian rhythm. Serum Corticosterone levels (RIA) and plasma catecholamine levels (REA) were measured. t-tests and standard error of mean were calculated with an OLIVETTI P 6040 Computer).
59
cormcoSTErlONE PLASMA LEVELS Corticosterone IJg/l
AOrlENALINE IA) 0 A+ PrlOPMNOLOL 0 un A+rlEGITINE
600
1]=====c 200
hrs
12 Fig. 1.
Results Plasma A-levels are enhanced against controls in all of the three test groups, whereby the A except at 12 h and A + Prop group show slightly lower levels than the A + Reg group (table 1: free plasma A-levels). Adrenaline treatment alone causes general enhancement of Corticosterone levels against controls which is highly significant (p < 0.01) after 12 h (fig. 1: Corticosterone plasma levels). In spite of the highest A levels, Corticosterone concentrations in plasma of the A + Reg group are even lower than controls after 6 and 20 h (fig. 1). Compared to the A + Prop group they are always significantly lower (fig. 1). Corticosterone levels of the A + Prop group are significantly higher than controls after 6 and 12 h. Adrenaline + Prop treatment leads to an earlier peak and also earlier decline of Corticosterone than A-treatment alone. Table 1. Free plasma adrenaline-levels
+ Prop
+ Reg
Hours
C
A
6 12 20
4.099 ± 0.511 3.704 ± 0.585 3.901 ± 0.453
6.625 ± 3.1:26 6.19 ± 1.545 15.176 ± 5.074 7.194 ± 1.664 7.;353 ± :2.162 6.:2:27 ± 1.159
12.401 ± 1.889 7.972 ± 1.002 13.912 ± 2.863
n
24
36
44
A
.til
A
X ± SEM X± SEM X ± SEM
Discussion Therefore we conclude that adrenergic LX-action enhances and fl-action suppresses Corticosterone serum levels. This is partly supported by SHIMIZU (1984) who found depressed ACTH-Ievels during simultaneous treatment with A and LX-blockers, which suggests LX-catecholaminergic effects operating via CRH - the last common step of nearly all ACTH-touching stimuli except vasopressin - ACTH and Corticosterone. On the other hand we could show enhancement of Corticosterone in animals treated 6 h with A + Prop against the A treated group. SHIMIZl did not observe increase in ACTH-levels during increased LX-action. This could either be due to the fact that ours was a long-term test, or to direct or indirect LX-influence~ on Corticosterone production which do not act via ACTH.
60
Exp. Pathol. 31 (1987) 1
Literature GIGUERE, V., J. COTE and F. LABRI, Characteristics of the alia-adrenergic stimulation of adrenocorticotropin secretion in rat anterior pituitary cells. Endocrinology 109, 757-762 (1981). - and F. LABRI, Additive effects of epinephrine and corticotropin-releasing factor (CRF) on adrenocroticotropin release in rat anterior pituitary cells. Biochem. Biophys. Res. Commun. 110, 456 to
462 (1983).
NAKAI, Y., H. IMURA, T. YOSHIMI, S. MATSUKURA, Adrenergic control mechanism for ACTH secretion in man. Acta Endocrinol. 74, 263-270 (1973). PORTA, S., A. SADJAK, S. SUPANZ, P. PURSTNER, W. KORSATKO, B. WABNEGG and U. ERTL, Peculiar long-term effects of catecholamines and their blockers in rats on insulin, glucose and pancreas. Exp. Pathol. 26, 241-245 (1984). SADJAK, A., H. G. KLINGENBERG, G. EGGER and S. SUPANZ, Evaluation of the effects of blood smelling, handling and anesthesia on plasma catecholamines in rats. Z. Versuchstierkd. 20, (5), (1983). SHIMIZU, K., Effect of alfa1 and alfa2-adrenoceptor agonists and antagonist on ACTH secretion in intact and in hypothalamic deafferentated rats. Japan. J. Pharmacol. 36, 23-33 (1984). TILDERS, F. J. H., F. BERKENBOSCH, F. P. G. and SMELlK, Adrenergic mechanism involved in the control of pituitary-adrenal activity in the rat: a p-adrenergic stimulatory mechanism. Endocrinology 110, 114-120 (1982). TIMMERMANS, P. B. M. W. M., and P. A. VAN ZWIETEN, Postsynaptic alia!" and alfa2-adrenoceptors in the circulatory system of the pithed rat: selective stimulation of the alfa 2-type by B-HT 933. Eur. J. Pharmacol. 63 199-202 (1980). (Received January 22, 1986)
Exp. Pathol. 31 (1987) 1
61