Study of the hypothermia induced by methionine sulfoximine in the rat.

L-Methionine sulfoximine (MSO) intraperitoneally injected at subconvulsive and convulsive doses induced a rectal hypothermia in the restrained rat maintained at an ambient temperature of 23 degrees C; this hypothermia developed during the preconvulsive period, and it was not suppressed by simultaneous injection of L-methionine which antagonized the behavioral effects of ammonia elevated contents in the central nervous system. The development of rectal hypothermia was faster when the injection of MSO was made into the lateral cerebral ventricle and particularly into the third ventricle. MSO-induced hypothermia seemed to be a poikilothermia-like state in the cold environment with retention of a normal regulation in the heat environment. Infusion of MSO into the anterior hypothalamic/preoptic (AH/PO) area induced a rapid rectal hyperthermia, but infused into the mammillary region MSO had no effect on rectal temperature. It is suggested that rectal hypothermia induced by MSO may be directly related to a depressive effect on glucose oxidative metabolism in cell structures, maybe astroglial cells, located in the vicinity of the ventricle or the capillary walls.