NALTREXONE STIMULATES LH SECRETION IN VITRO FROM THE COMMON CARP (CYPRINUS CARPIO L.) PITUITARY GLAND
Magdalena Socha, Mirosława Sokołowska-Mikołajczyk, Tomasz Mikołajczyk, Jarosław Chyb, Piotr Epler
Department of Ichthyobiology and Fisheries, University of Agriculture, Kraków-Mydlniki, Poland
ABSTRACT. The effects of naltrexone on the in vitro luteinizing hormone (LH) secretion from whole pituitary glands as well as from dispersed pituitary cells of common carp (Cyprinus carpio L.) in primary cell culture were studied. The perifusion of whole pituitary glands with naltrexone at a concentration of 10-4 M caused a significant increase of LH secretion compared to the control. This finding suggests that opioid peptides can indirectly affect LH secretion at the pituitary level, probably through the nerve terminals containing GnRH and/or DA present in the pituitary. In the perifusion of dispersed pituitary cells with naltrexone at concentrations of 10-6 or 10-4 M, significant increases of LH levels were found. Similar results were observed in static culture of dispersed carp pituitary cells: after 4 or 24 hours of culture in the medium containing naltrexone at concentrations of 10-6, 10-4 or 10-2 M, a dose-dependent, statistically significant increase of LH secretion to the culture medium was found. The results from dispersed pituitary cell perifusions or cell culture with naltrexone indicate that this antagonist directly affects the pituitary cells and stimulates LH release from carp gonadotrophs.
Key words: COMMON CARP (CYPRINUS CARPIO), IN VITRO, LH, NALTREXONE
CORRESPONDING AUTHOR:
Magdalena Socha, Akademia Rolnicza, Katedra Ichtiobiologii i Rybactwa, ul. Prof. T. Spiczakowa 6, 30-199 Kraków-Mydlniki, Tel./Fax: +48 (12)6375176, +48(12)6385979;
e-mail:rzbienia@cyf-kr.edu.pl