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Acta Physiologica 2011; Volume 202, Supplement 684
The Joint Conference (FAMÉ 2011) of the LXXVth Meeting of the Hungarian Physiological Society, XVIth Meeting of the Hungarian Society of Anatomists, Experimental Section of the Hungarian Society for Experimental and Clinical Pharmacology and Hungarian Society for Microcirculation and Vascular Biology
6/8/2011-6/11/2011
Pécs, Hungary
THE ACTIONS OF THE ENDOMORPHINS AND THE UROCORTINS ON THE HYPOTHALAMIC AMOUNTS OF CRF AND AVP IN RATS
Abstract number: P2
Bagosi1 Zs., Csabafi1 K., Jaszberenyi1 M., Foldesi2 I., Gardi2 J., Szabo1 G.
Aims:
There have been several reports demonstrating the actions of the endomorphins (EM1 and EM2), endogenous ligands for mu-opioid receptors (MOR1 and MOR2), and the urocortins (UCN1, UCN2 and UCN3), endogenous ligands for corticotropin-releasing factor receptors (CRFR1 and CRFR2), on ACTH and corticosterone release in mammals. However, there are poor results concerning the interactions between these putative modulators and the principal regulators of the stress response, CRF and AVP. This study aims to determine the connection between these neuropeptides and neurohormones in male Wistar rats.
Methods:
The animals were decapitated 30 min after the intracerebroventricular administration of the peptides, their hypothalami were isolated and homogenised and their trunk blood were collected and centrifuged. The amounts of CRF and AVP in the homogenised tissue were measured by ELISA and RIA test, respectively, while the plasma concentration of corticosterone was determined by chemical assay.
Results:
EM1, EM2 and UCN1 dose-dependently elevated the plasma corticosterone concentration; in addition, the most effective doses of EM1 (5 mg), EM2 (0.5 mg) and UCN1 (2 mg) elicited significantly the hypothalamic CRF production. The administration of UCN1 (2 mg) elevated the AVP production also. UCN2 and UCN3 produced similar biphasic dose-response curves, both decreasing the hypothalamic CRF levels in physiological ranges (<= 2 mg), but increasing it in pharmacological doses (>= 5 mg). These changes were mirrored by the plasma corticosterone levels, but not accompanied by hypothalamic AVP release.
Conclusion:
These results suggest that the endomorphins activate the hypothalamic-pituitary-adrenal (HPA) axis and that CRF, but not AVP, mediates this process. This study also sustains that the urocortins are fine-tuners of the HPA axis determining antagonistic changes of the corticosterone secretion, and that these dose-dependent or time-dependent responses are initiated or associated with changes of CRF production.
Support:
ETT 355-08/2009 and TÁMOP 4.2.1B
To cite this abstract, please use the following information:
Acta Physiologica 2011; Volume 202, Supplement 684 :P2