Hypothalamic neuronal histamine modulates energy balance in rats.

Effects of hypothalamic histamine on food intake and adaptive behavior to altered ambient temperature were assessed in rats by manipulating histamine endogenously. Infusion of a-fluoromethylhistidine (FMH) into the third cerebroventricle elicited meals dose dependently (p less than 0.01), when hypothalamic histamine was normally high. The effect of FMH was attenuated, and thioperamide conversely suppressed food intake (p less than 0.05), when the probes were performed during the minimum histamine content. The ventromedial hypothalamus and the paraventricular nucleus were identified as the active target loci. Hypothalamic histamine level was lowered at 4 degrees C and raised at 31 degrees C ambient temperature. FMH attenuated both the elevated histamine level and adaptive behavior at 31 degrees C. Neuronal histamine may play a physiological role in feeding suppression through those hypothalamic nuclei, and also in adaptive behavior in abnormal ambient temperature.