Peptidergic innervation of caudal neurosecretory neurons.

Luteinizing hormone releasing hormone (LHRH)-like immunoreactivity was observed in neurosecretory neurons at mesencephalic levels of the poecilid brain. This nucleus of peptide producing neurons has been shown to project to the spinal cord neurosecretory complex in this species. LHRH-like immunoreactivity was localized in fibers and terminals surrounding caudal neurosecretory cells. This investigation suggests that there is a mesencephalic descending LHRH innervation of caudal neurosecretory neurons.