Induction of Fos-like immunoreactivity in the lower brainstem and the spinal cord of the rat by intraperitoneal administration of an endogenous satiety substance, 2-buten-4-olide.

Induction of Fos in neurons by intraperitoneal injection of 2-buten-4-olide (2-B40), an endogenous satiety substance, was studied immunohistochemically in the brainstem and spinal cord of the rat. Rats injected intraperitoneally with 2-B40 (100 mg/kg) were allowed to survive for 2 h before perfusion. Fos-like immunoreactivity was observed in neurons of the intermediolateral nucleus, ventral reticular formation, lateral reticular nucleus, nucleus of the solitary tract, locus coeruleus, lateral parabrachial nucleus and dorsal raphe nucleus, as well as in tyrosine hydroxylase-immunoreactive neurons of the cell groups A1, A2, A5, A6, A7, C1, C2 and C3.