ISSN:
1573-6830
Keywords:
alpha-adrenergic
;
corticotropin-releasing hormone
;
HPA axis
;
hypothalamic paraventricular nucleus
;
stress
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract SUMMARY 1. The role of α1-adrenergic receptors on CRH mRNA levels in the PVN was studied in control and stressed rats receiving i.c.v. injections of the α1-adrenergic agonist, methoxamine, or the α1- antagonist, prazosin. 2. Plasma ACTH increased significantly 60 min and 4 hr after a single injection of methoxamine (100 μg, i.c.v.). No desensitization of this response was observed after repeated injections every 6 hr for 24 hr. Concomitantly, POMC mRNA in the anterior pituitary increased by 25% at 4 hr after a single injection and by 96% after repeated injections. 3. CRH mRNA levels in the PVN increased by 131% after repeated injections for 24 hr, but were unchanged 4 hr after a single injection. Central α1-adrenergic blockade with prazosin did not prevent the increases in CRH mRNA following 4 hr of acute stress, but significantly reduced the increases observed 24 hr after an i.c.v. injection of 75 μg of colchicine or after repeated i.p. hypertonic saline injections every 8 hr. 4. These studies demonstrate that while α1-adrenergic receptors contribute to long-term increases of CRH mRNA levels in the PVN during prolonged stress, other factors are likely to be involved in the stimulation of CRH mRNA following acute stimulation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007098724683
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