Histaminergic neurons in the hypothalamic thermoregulatory pathways.

Based on neurochemical and neurophysiological research, especially over the past decade, considerable evidence exists for accepting histamine as a central neurotransmitter along-side the other neuroamines. The data supporting a functional role are not complete, but they do exhibit a consistent pattern in the case of the central thermoregulatory pathways. Thus, the region of the thermoregulatory centers in the rostral hypothalamus contains relatively high concentrations of histamine and the enzyme systems for its synthesis and degradation; degeneration studies indicate histaminergic pathways in the hypothalamus; thermoregulatory changes can be induced by activation of either H1 or H2 receptors; behavioral studies reveal different functional roles for H1 and H2 receptors; and the thermoregulatory responses to histamine are detectable across different species, even in nonhomeothermic animals. This evidence supports assigning a transmitter function to histamine in the central thermoregulatory pathways that would appear to be as well-founded as the comparable data amassed for other neuroamines.