β-Endorphin-induced Inhibition of Vitellogenic Follicular Growth in the Fish Oreochromis mossambicus: Evidence for Opioidergic Mediation of Ovarian Stress Response
Article first published online: 29 JAN 2013
Copyright © 2013 Wiley Periodicals, Inc.
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology
Volume 319, Issue 3, pages 156–165, March 2013
How to Cite
2013. β-Endorphin-induced Inhibition of Vitellogenic Follicular Growth in the Fish Oreochromis mossambicus: Evidence for Opioidergic Mediation of Ovarian Stress Response J. Exp. Zool. 319A:156–165., .
- Issue published online: 6 MAR 2013
- Article first published online: 29 JAN 2013
- Manuscript Accepted: 19 DEC 2012
- Manuscript Revised: 6 OCT 2012
- Manuscript Received: 27 JUL 2012
- Department of Science and Technology (DST), Govt. of India, New Delhi. Grant Number: SR/S0/AS-69/2005
The opioid peptide β-endorphin (β-EP) is known to play modulatory role in vertebrate reproduction. The objective of the present study was to determine the influence of β-EP and the opioid receptor antagonist naltrexone (NALT) on follicular development in normal, and stressed female tilapia Oreochromis mossambicus. Administration of 4 µg β-EP, but not 0.5 or 1.5 µg β-EP daily for 22 days caused a significant reduction in the mean GSI, HSI, and number of Stage IV (vitellogenic) follicles compared to experimental controls during the prespawning phase of the ovarian cycle. Furthermore, the Stage V (vitellogenic) follicles were completely absent during the prespawning phase concomitant with the significantly lower serum levels of estradiol and cortisol in 4 µg β-EP treated fish compared to experimental controls. On the other hand, exposure of the fish to mild acute stressors for 22 days caused changes in the ovary similar to that of high dose of β-EP, whereas administration of NALT attenuated these effects. The results reveal that β-EP exerts inhibitory effect on the vitellogenic follicular growth through the suppression of ovarian steroidogenesis. The study provides evidence for the opioidergic mediation of the ovarian stress response for the first time in fish. J. Exp. Zool. 319A:156–165, 2013. © 2013 Wiley Periodicals, Inc.