IMMUNOCYTOCHEMICAL LOCALIZATION OF 5-HT(1A) RECEPTORS IN THE RAT IMMATURE CEREBELLUM

The serotonin 5-HT1A receptors were visualized in the cerebellar vermi s of 8-day-old and adult rats by immunocytochemistry using anti-5-HT1A receptor antibodies raised against a synthetic peptide corresponding to a highly selective portion of the receptor amino acid sequence (El Mestikawy et al, Neurosci Lett 118,189-192,1990). The 5-HT1A receptor- like immunoreactivity was particularly abundant in the posterior lobul es (IXB-X) of the immature vermis where it was found in the molecular- Purkinje cell layers. Immunostaining was confined to the plasmic membr ane of the Purkinje cell somas, dendrites and perhaps axons (at their somatic emergence) suggesting that 5-HT1A receptors might participate in non-junctional 5-HT neurotransmission in the immature cerebellum.