EXPRESSION OF PITUITARY ADENYLATE-CYCLASE ACTIVATING POLYPEPTIDE (PACAP) IN THE POSTNATAL AND ADULT-RAT CEREBELLAR CORTEX

IN adult rat, immunostaining for pituitary adenylate cyclase activatin g polypeptide (PACAP) was demonstrated in the soma and dendrites of Pu rkinje cells and in nerve fibres around granule cells. PACAP in the Pu rkinje cells was confirmed by the presence of mRNA. The concentration of PACAP-38 was high after birth and declined to adult levels within a few weeks. At birth PACAP-immunoreactive nerve fibres and a few cells were present in the Purkinje cell layer, but already at postnatal day 7 an adult PACAP immunostaining pattern was found. The findings sugge st that PACAP could be a neurotransmitter in the adult cerebellum and provide a morphological correlate for the reported in vitro anti-apopt otic PACAP effects on cerebellar granule cells from 1-week-old rats. ( C) 1998 Rapid Science Ltd.