摘要:

The present study was conducted to examine roles of brain monoamines and opioid peptides in growth hormone (GH) secretion in unanesthetized, freely behaving rats. The administration of chlorpromazine (CPZ, 300 μg/100 g, i.v.), an antagonist of brain monoamines, to rats that were passively immunized with antiserum to somatostatin immediately lowered plasma GH levels and inhibited episodic GH secretion. An intraventricular injection of β-endorph¡n (3.5 μg) stimulated GH secretion. This effect was completely inhibited by the prior administration of naloxone (100 μg/100 g, i.v.), a specific antagonist of opioid peptides but not by CPZ. In addition, the administration of naloxone did not inhibit episodic GH secretion. The results suggest that CPZ inhibits episodic GH secretion via a factor(s) other than somatostatin. It is also inferred that brain monoamines. but not opioid peptides, play major roles in the regulation of episodic GH secretion in

ISSN:0028-3835    

DOI:10.1159/000123021

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Thalamic and intact pigeons were equipped with a chronic arterial catheter and with a miniature electronic device for hypothalamic telestimulation. Chronic catheterization allowed for repetitive blood sampling in freely moving birds subjected to either systemic (ether inhalation) or neurogenic (electrical foot shocks) stress and to electrical stimulation of the hypothalamic corticotropic area. Corticosterone levels were determined by protein binding assay at 2-, then 5- and 10-min intervals, for 100 min. Basal and experimentally modified plasma corticosterone concentrations were not different in thalamic and intact pigeons. Corticosterone profile exhibited episodic increase including three peaks at 12, 35 and 60 min after stress application. Only the first peak of plasma corticosterone appeared after hypothalamic stimulation. It is suggested that extrahypothalamic neuronal networks are responsible for the long-lasting repetitive adrenocorticotropic response to stress, which are not involved in the single response to hypothalamic stimulation itself. Furthermore, such extrahypothalamic neuronal networks should be located at the diencephalic or rhombencephalic level since hemispherectomized pigeons exhibited the same profile of stress-induced episodic hypercorticosteronemia as seen in intact birds.

ISSN:0028-3835    

DOI:10.1159/000123022

出版商:S. Karger AG    

年代:1980

数据来源: Karger