Stimulation by Dopamine of Luteinizing Hormone-Releasing Hormone (LHRH) Release from the Mediobasal Hypothalamus in Male Rats1

Publisher Website
Google Scholar
Abstract
Effects of neurotransmitters on in vitro release of LHRH from fragments of mediobasal hypothalamus were investigated. Incubations were carried out for 10 min in a Locke-HEPES medium in the presence of dithioerythritol (10-5 M) and bacitracin (2 .times. 10-5 M) to prevent catecholamine oxidation and peptide degradation, respectively. Addition of 3 .times. 10-9 M to 10-7 M concentrations of dopamine (DA) to the incubation medium released dose-related amounts of LHRH from hypothalamic fragments, including the medial and lateral palisadic zones of the median eminence, which contain most of the tubero-infundibular DA terminals. LHRH release did not occur when norepinephrine (10-7 M) was added instead of DA nor was it obtained when DA was incubated with the caudal portion of the mediobasal hypothalamus or the organum vasculosum of the lamina terminalis, which also contain LHRH but are poorly innervated by DA neurons. The effect of DA on palisadic structures was blocked by the addition of pimozide. It seemed to be steroid-dependent, since it was observed on fragments of median eminence sampled from normal, but not from castrated male rats. The palisadic zone contains specific DA receptors which trigger LHRH release in the presence of steroid hormones.

This publication has 10 references indexed in Scilit: