Corticotropin-releasing factor mRNA increases in the inferior olivary complex during harmaline-induced tremor

This study reports that corticotropin-releasing factor (CRF) expression within the inferior olivary complex (IOC) of the cat is increased 8 h after administration of the tremor-inducing beta-carboline harmaline. Following harmaline treatment, hybridization of an oligodeoxynucleotide complementary to CRF mRNA increased significantly in the dorsal accessory olive, subnuclei A and C of the medial accessory olive and the dorsal cap of Kooy, a subnucleus thought previously to be unresponsive physiologically to harmaline. At this early time point, greater increases in CRF mRNA hybridization were present in the caudal than the rostral IOC. These results support published reports that harmaline-mediated effects are more profound within the caudal than the rostral IOC, but also suggest that harmaline mediates cellular responses in inferior olivary neurons which are not related to activation of rhythmic firing.