Wigger, A. and Neumann, Inga D. (2002) Endogenous opioid regulation of stress-induced oxytocin release within the hypothalamic paraventricular nucleus is reversed in late pregnancy: A microdialysis study. NEUROSCIENCE, 112 (1): PII S0306-. pp. 121-129. ISSN 0306-4522, 1873-7544
Full text not available from this repository.Abstract
Oxytocin secretion into blood in response to swim stress is differentially regulated by endogenous opioids ill virgin and pregnant rats. Here, the influence of endogenous opioids on oxytocin release within the hypothalamic paraventricular and supraoptic nuclei was investigated using microdialysis in virgin and pregnant (day 19-21) rats. Rats fitted with a U-shaped microdialysis probe 3 days before testing were injected with naloxone (5 mg/kg body weight, s.c.) or vehicle (sterile saline) and, 3 min later, were forced to swim (10 min at 19degreesC). Within the paraventricular nucleus, basal and stimulated oxytocin release did not significantly differ between vehicle-treated virgin and pregnant rats. After naloxone, local oxytocin release in response to swimming was lowered in virgin rats (P<0.01), whereas it was further increased in pregnant rats (P<0.01). Within the supraoptic nucleus, basal oxytocin release was significantly lower in pregnant compared to virgin rats (P<0.01). Forced swimming induced a similar rise in intranuclear oxytocin release in both vehicle-treated virgin and pregnant rats, but peak levels were still higher in the virgin controls. In contrast to the paraventricular nucleus, naloxone did not alter swim-induced oxytocin release within the supraoptic nucleus either ill virgin or pregnant rats. Vasopressin release in the paraventricular nucleus was also increased by forced swimming but there was no effect of pregnancy or naloxone oil it. In summary, in pregnancy, basal and stress-induced oxytocin release within the paraventricular nucleus was not changed, whereas it was blunted within the supraoptic nucleus. Further, within the paraventricular nucleus the excitatory effect of endogenous opioids on local oxytocin release seen in virgins was switched into an inhibitory action in pregnancy. In contrast, endogenous opioids were evidently not involved in the regulation of swim-induced oxytocin release within the supraoptic nucleus either in virgin or pregnant rats. Thus, pregnancy-related neuroendocrine plasticity also includes site-specific functional alterations in opioid receptor-mediated actions in the hypothalamus. (C) 2002 IBRO. Published by Elsevier Science Ltd. All rights reserved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | RAT SUPRAOPTIC NUCLEUS; VASOPRESSIN GENE-EXPRESSION; PARTURITION-RELATED EVENTS; ANXIETY-RELATED BEHAVIOR; PITUITARY-ADRENAL AXIS; MILK-EJECTION REFLEX; BRAIN BETA-ENDORPHIN; LACTATING RATS; IN-VITRO; MAGNOCELLULAR NEURONS; swimming; vasopressin; naloxone; reproduction; rat |
| Subjects: | 500 Science > 590 Zoological sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Zoologie > Tierphysiologie/Neurobiologie (Prof. Dr. Inga Neumann) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 17 Nov 2021 16:24 |
| Last Modified: | 17 Nov 2021 16:24 |
| URI: | https://pred.uni-regensburg.de/id/eprint/40808 |
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