[Distribution of substance P and methionine enkephalin in dorsolateral pontine tegmentum of the cat. Immunofluorescence study].

Immunofluorescence technique has been used to map out Substance P (SP) and Met-Enkephaline (Met-Enk) nerve fibres and perikarya in the dorsolateral part of the cat pontine tegmentum. Antibody to tyrosine hydroxylase was used as a marker for catecholamine cell bodies to define the locus coeruleus complex. Abundant SP and Met-Enk fibres were seen surrounding the locus coeruleus (LC) with dense plexus of terminals in parabrachial (PB) nuclei and lateral periventricular gray whereas only few immunoreactive fibres occur in the LC proper. Met-Enk positive perikarya are localized in LC and lateral parabrachial nucleus. These preliminary results suggest possible interactions between peptidergic neurons and catecholaminergic neurons.