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Effects of galanin on the proliferative activity of immature rat adrenal gland, as investigated by metaphase-arrest and PCNA-immunostaining techniques
No full textEffect of pentagastrin on steroid secretion and proliferative activity of regenerating rat adrenal cortex
No full textThe effects of three subcutaneous injections of 3 nmol/100 g body weight of the cholecystokinin type 2 (CCK2) receptor agonist pentagastrin on adrenocorticotrophic hormone (ACTH) and corticosterone secretion and proliferative activity of regenerating rat adrenal cortex were investigated. Pentagastrin did not alter either ACTH and corticosterone plasma concentrations or the adrenal mitotic index at day 5 of regeneration. In contrast, it increased (by about 50%) the adrenal mitotic index at day 8 of regeneration, and the effect was blocked by the simultaneous administration of equimolar doses of the CCK2-receptor antagonist PD-135,158. It is suggested that the activation of CCK2 receptors exerts a growth promoting action on the regenerating rat adrenal cortex
Effects of endogenous galanin on the growth of regenerating rat adrenal gland as investigated by the metaphase-arrest and the PCNA-immunostaining techniques
No full textWe have investigated the effects of three subcutaneous injections of 2 nmol/100 g body weight of galanin and its receptor antagonist (galanin-A) [D-Thr 6,D-Trp 8,9,-15-ol]-galanin 1-15 on the proliferative activity of regenerating rat adrenal cortex. The metaphase-arrest and the proliferating-cell nuclear antigen (PCNA)-immunostaining techniques were used to estimate the number of M phase (metaphase index) and S phase cells (PCNA index), respectively. Galanin-A raised the metaphase index at both day 5 and day 8 of regeneration. Galanin was per se ineffective, but reversed the galanin-A effect at day 8. Neither galanin nor galanin-A changed PCNA index at day 5. Galanin evoked a moderate increase in PCNA index at day 8. Taken together, these findings indicate that endogenous galanin exerts a tonic maximal inhibitory effect on adrenal regeneration in the rat
Endogenous cholecystokinin (CCK) exerts a tonic inhibitory action on rat pituitary-adrenocortical axis, acting through the CCK-B receptor subtype
No full textEffects of neuropeptides B and W on the secretion and growth of rat adrenocortical cells
No full textNeuropeptide-B (NPB) and neuropeptide-W (NPW) are recently discovered endogenous
ligands of the GPR7- and GPR8-receptors (R), which in humans are expressed in the
hypothalamus and probably involved in the regulation of energy homeostasis and
neuroendocrine axes. GPR8-Rs are absent in rodents, where the GPR8-like-R has
been described. Reverse transcription-polymerase chain reaction detected the
expression of NPB, NPW, GPR7-R and GPR8-like-R mRNAs in rat adrenocortical cells
(both freshly-dispersed and 4-day-cultured cells). NPB did not acutely (60-min
exposure) alter basal aldosterone secretion from freshly dispersed zona
glomerulosa cells, while NPW raised it. Both NPB and NPW enhanced ACTH-stimulated
aldosterone secretion and did not affect either basal or ACTH-stimulated
corticosterone production by dispersed zona fasciculata/reticularis (ZF/R) cells.
The prolonged (4-day) exposure to NPW, but not NPB, raised corticosterone
secretion from cultured ZF/R cells, and both neuropeptides increased the
proliferation rate of cultured cells. Taken together, our findings indicate that
NPB and NPW affect rat adrenocortical function, so they may be included in that
large family of peptides involved in the autocrine-paracrine stimulation of
secretion and growth of adrenal cortex
Expression of neuropeptides B and W and their receptors in endocrine glands of the rat
No full textNeuropeptides B and W (NPB and NPW) have been identified as endogenous ligands of the G protein-coupled receptors (GPR) 7 and 8, which in humans are expressed in the hypothalamus and probably involved in the regulation of energy homeostasis and feeding behavior. GPR8 is absent in the rat, where the GPR8-like receptor (GPR8-LR) has been described. Reverse transcription-polymerase chain reaction detected the expression of NPB, NPW, GPR7 and GPR8-LR mRNAs in the hypothalamus, anterior pituitary, thyroid and parathyroid glands, pancreatic islets, adrenal glands, ovary and testis of the rat. Immunocytochemistry demonstrated the presence of NPB and NPW immunoreactivities in these same glands. Radioimmune assay showed that the bolus intraperitoneal injection of 2 nmol/100 g NPB or NPW raised the plasma levels of parathyroid hormone, corticosterone and testosterone. NPB also increased the blood concentration of thyroxine, and NPW that of ACTH and estradiol. Taken together, these findings allow us to suggest that NPB and NPW play a role in the autocrine-paracrine functional regulation of the endocrine system in the rat
Effects of leptin on the response of rat pituitary-adrenocortical axis to ether and cold stresses
No full textLeptin is a hormone mainly secreted by the adipose tissue, which acts through specific receptors widely distributed in the body tissues, including hypothalamopituitary-adrenal axis. We have investigated the effects of a subcutaneous bolus injection of 5 nmol/kg leptin on the pituitary-adrenocortical function in both normal and ether- or cold-stressed rats. Blood concentrations of ACTH, aldosterone and corticosterone were measured by specific RIA 2 or 4 h after the leptin injection. Leptin administration to normal rats resulted in significant rises in the blood levels of ACTH, aldosterone and corticosterone at 2 h, but not at 4 h. Ether and cold stresses markedly increased hormonal blood concentrations at both 2 and 4 h. Leptin magnified ACTH response to ether stress at 2 h, but depressed it at 4 h, and enhanced aldosterone response at 2 h, without affecting corticosterone response. Leptin increased ACTH response to cold stress at both 2 and 4 h, without altering aldosterone and corticosterone responses. In light of these findings, we conclude that: (i) leptin evokes a middle transient activation of the pituitary-adrenocortical axis of rats under basal conditions; (ii) leptin inhibits the ACTH response to ether stress, but magnifies that to cold stress; and (iii) the leptin-evoked changes in the blood level of ACTH are not paralleled by significant modifications in the secretory activity of the adrenal cortex, which probably undergoes a maximal stimulation under stressful conditions
Effects of neuropeptides B and W on the rat pituitary-adrenocortical axis: In vivo and in vitro studies
No full textNeuropeptides (NP) B and W are hypothalamic peptides involved in the regulation of feeding and neuro-endocrine axes. Evidence has been provided that NPB and NPW act on both the central and the peripheral branches of the rat hypothalamic-pituitary-adrenocortical axis, and we carried out in vivo and in vitro studies to gain insight into this topic. Reverse transcription-polymerase chain reaction showed the expression of NPB, NPW and their receptors in both adrenal cortex (zonae glomerulosa and fasciculata-reticularis) and adrenal medulla, where immunocytochemistry also detected the presence of abundant NPB- and NPW-immunoreactivity. The acute subcutaneous administration of NPB (0.5 or 1.5 nmol/100 g) did not alter ACTH plasma concentration, while that of NPW (1.5 nmol/100 g) decreased it. Neither NPB nor NPW affected the blood level of aldosterone, while both peptides (0.5 nmol/100 g) raised that of corticosterone. NPB (10(-6) M) lowered ACTH-stimulated aldosterone secretion, and basal and ACTH-stimulated corticosterone production from adrenal quarters containing both cortical and medullary tissues. NPW (10(-6) M) enhanced basal aldosterone secretion from adrenal quarters, and the effect was suppressed by the beta-adrenoceptor antagonist l-alprenolol (10(-5) M). NPW did not affect corticosterone production. Collectively, our findings allow us to draw the following tentative conclusions: i) ACTH-independent extra-adrenal mechanism(s) are operative in vivo, by which NPB and NPW stimulate adrenal glucocorticoid, but not mineralocorticoid secretion; ii) in vitro the interaction of NPB with adrenal medulla activates unknown mechanism(s) hampering adrenocortical steroidogenic machinery; and iii) NPW stimulates in vitro aldosterone secretion by enhancing the release of medullary catecholamines, which in turn activate beta-adrenoceptors located on zona glomerulosa cells
Modulatory effects of orexins on the function of rat pituitary-adrenocortical axis under basal and stressful conditions
No full textOrexins A and B are two hypothalamic peptides, involved in the control of feeding. We have investigated the effects of a bolus subcutaneous injection of 10 nmol/kg body weight of orexins on pituitary-adrenocortical function in both normal and ether- or cold-stressed rats. The blood concentrations of adrenocorticotropic hormone (ACTH), aldosterone and corticosterone were measured by specific radioimmune assay 60 and 120 min after the injection. In non-stressed rats, orexin-A raised the blood levels of the three hormones significantly at 60 min, and orexin-B increased aldosterone and corticosterone concentration significantly at 60 min without affecting that of ACTH. Orexin-A did not affect the pituitary-adrenocortical response to ether stress, while orexin-B increased ACTH and corticosterone responses significantly at 120 and 60 min respectively. Both orexins magnified the ACTH response to cold stress significantly, without altering aldosterone or corticosterone blood concentrations. We conclude that orexins (i) evoke a transient activation of the rat pituitary-adrenocortical axis, acting on both its central and peripheral branch; and (ii) exert a minor modulatory role on pituitary-adrenocortical responses to stresses, their effects being dependent upon the type of stressor
Effect of cerebellin on the pituitary-adrenocortical function in adult rats and the proliferative activity of immature and regenerating rat adrenal cortex
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