THE SYNTHESIS OF MELANIN-CONCENTRATING HORMONE IS STIMULATED BY VENTROMEDIAL HYPOTHALAMIC-LESIONS IN THE RAT LATERAL HYPOTHALAMUS - A TIME-COURSE STUDY

The activity of melanin-concentrating (MCH) neurons, was investigated by immunocytochemical and hybridocytochemical techniques in male rats bearing limited lesions of the ventromedial hypothalamic nuclei (VMN). 2 days after operation, the abundance of immunoreactive cell bodies a nd fibres and the intensity of labelling seemed slightly decreased in lesioned rats as compared to controls while no significant difference could be detected in MCH gene expression. After 8 days, synthesis, sto rage and transport of MCH appeared strongly stimulated and this stimul ation lasted until the end of the experiment (day 35), suggesting that VMN plays a physiological role in controlling MCH neuron activity.