Testosterone Modulates Oxytocin Binding in the Hypothalamus of Castrated Male RatsJohnson A.E. · Coirini H. · McEwen B.S. · Insel T.R.
aSection on Comparative Studies of Brain and Behavior, Laboratory of Clinical Sciences, National Institute of Mental Health, Poolesville, Md.; bLaboratory of Neuroendocrinology, The Rockefeller University, New York, N.Y., USA
Oxytocin (OT) binding sites are modulated by estrogens in several brain regions including the ventromedial hypothalamic nucleus (VMN) in both male and female rats. To further study steroid regulation of OT receptor binding, we examined the effect of androgen replacement in castrated male rats on OT binding with quantitative autoradiographic methods. Castrated adult male rats were treated with either 250 µg testosterone propionate (TP) or oil for 2 days and killed 48 h after the last injection. Brain sections through the preoptic area and VMN were labeled with 5.0 nM [3H]-OT ± 5.0 µM unlabeled OT or 1.0 µM [Thr4·Gly7OT and apposed to tritium-sensitive film for 7 weeks. Results of this study show that TP increased [3H]-OT binding up to 5-fold in the ventrolateral VMN and 4-fold in the bed nucleus of the stria terminalis. In addition [Thr4Gly7]OT completely displaced [3H]-OT binding in the VMN indicating that binding in this brain region was specific to OT receptors. Because estrogens also increase OT receptor binding in male rats, it is possible that TP affects OT binding after being converted by aromatase to estradiol.
Allan E. Johnson, Section of Comparative Studies of Brain and Behavior, Laboratory of Clinical Sciences, National Institute of Mental Health, PO Box 289, Poolesville, MD 20837 (USA)
Received: August 19, 1988
Accepted after revision: December 5, 1988
Published online: April 02, 2008
Number of Print Pages : 5
Neuroendocrinology (International Journal for Basic and Clinical Studies on Neuroendocrine Relationships)
Vol. 50, No. 2, Year 1989 (Cover Date: 1989)
Journal Editor: Millar R.P. (Edinburgh)
ISSN: 0028–3835 (Print), eISSN: 1423–0194 (Online)
For additional information: http://www.karger.com/NEN