Monosodium glutamate induced lesions of the arcurate nucleus. II. Fluorescence histochemistry of catecholamines.

The effect of the monosodium glutamate (MSG) induced lesion of the arcuate nucleus on catecholamines in the arcuate nucleus and median eminence of the mouse hypothalamus was determined using the Falck-Hillarp histofluorescence technique. The number of fluorescent perikarya in the arcuate nucleus of treated animals was decreased approximately 60%; the fluorescence intensity of surviving neurons was notably reduced. These changes were accompanied by a reduction in the intensity of fluorescence in the median eminence. Pretreatment of control and MSG-lesioned animals with a monoamine oxidase inhibitor (pargyline) greatly increased fluroescence in the median eminence and arcuate nucleus of both groups. However, the number of fluorescing perikarya of the arcuate nucleus of the normal pargyline treated group far exceeded that of the pargyline MSG animals. It is concluded that neonatally administered MSG caused destruction of a large number of dopaminergic arcuate perikarya.