Feeding-related immune responsive brain stem neurons: association with CGRP

Using dual-labeling in situ hybridization histochemistry, the neurotransmit ter expression of immune-responsive neurons in the pontine parabrachial nuc leus, a major relay for interoceptive information, was investigated. Intrav enous injection of bacterial wall lipopolysaccharide resulted in dense c-fo s mRNA expression in the external lateral parabrachial nucleus, and a major ity of the c-fos expressing cells also expressed calcitonin gene-related pe ptide (CGRP) mRNA. In contrast CGRP-positive cells in the adjoining externa l medial subnucleus were c-fos negative. Taken together with previous hodol ogical and behavioral studies, these data suggest that CGRPergic parabrachi al neurons may mediate lipopolysaccharide-induced anorexia by means of thei r projection to central nucleus of the amygdala. NeuroReport 12:2399-2403 ( C) 2001 Lippincott Williams & Wilkins.