CRF and Vasopressin gene expression in Stress Response

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Whereas CRF is localized in the parvocellular division, vasopressin (AVP) is present in both parvo- and magnocellular divisions of the hypothalamic paraventricular nucleus (PVN) . Norepinephrine (NE), as a neurotransmitter, has been proposed to convey stimulatory signals to both divisions of the PVN.To elucidate whether NE regulates CRF and AVP gene expression diffferentially in the PVN we examined the effects of NE on CRF and AVP gene expression in vivo .Stainless steel guide cannulas were implanted stereotaxically into male Wistar rats aiming at 2 mm above the left PVN under pentobarbital anesthesia. One week following surgery, a 31-G needle was inserted into the guide cannula to reach the dorsolateral border of the PVN .NE (50 nmol) dissolved in artificial CSF (100 nl), or CSF alone, was injected into the left PVN of conscious rats. Rats were decapitated at 0,15,30,60,90, and 120 min following NE injection (or, 30 min following CSF injection), and trunk blood was collected for corti … More costerone (CORT) RIA,then the brain was removed and stored at -80C.All experiments were carried out from 0800-1200 h. Hypothalami were sectioned at 10 mum on a crmuyostat and mounted onto slides. Antisense 35S-labeled cRNA probes were synthesized for rat CRF exon 2, CRF intron, AVP exon C, AVP intron 1. In situ hybridization was carried out on sections taken every 70 mum throughout the PVN,and the tissue was exposed to X-ray film.Signal intensity on each side of the PVN was quantitated from 10 sections per animal. We found that plasma CORT levels increased markedly following NE injection, reached a peak at 60 min, and remained high at 120 min. CRF hnRNA increased dramatically at 15 min to levels approximately 70 times as high as those in controls, and returned to baseline by 90 min. CRF mRNA incresed by approximately 30% at 90 min. Both CRF hnRNA and mRNA levels were not significantly different from the controls 30 min following CSF injection. AVP hnRNA as well as mRNA levels, examined at 30 and 120 min, were not significantly different from those in controls. These results suggest that NE regulates CRF and AVP gene transcription differentially in the PVN. Less