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.