Luteinizing hormone-releasing hormone increases dopamine turnover in the lateral palisade zone of the median eminence and reduces noradrenaline turnover in the nuc. preopticus medialis of the hypophysectomized male rat.

By means of catecholamine fluorescence histochemistry in combination with quantitative microfluorimetry the effects of luteinizing hormone-releasing hormone (LH-RH) has been studied on the amine levels and turnover in discrete catecholamine (CA) nerve terminal populations in the hypothalamus of the hypophysectomized male rat. LH-RH highly selectively increases dopamine (DA) turnover in the lateral palisade zone of the median eminence and highly selectively reduces noradrenaline turnover in the nucleus preopticus medialis without influencing amine levels in these CA nerve terminal systems. It is suggested that the ultrashort feed-back action of LH-RH involves increased release of DA in the lateral palisade zone leading to activation of the DA receptor inhibiting LH-RH release as well as a reduced noradrenaline release in the nucleus preopticus medialis leading to a reduced excitatory influence on the LH-RH neurons at the soma-dendritic level.