Effect of habenular nucleus in 5-HT ascending pressor pathways

The blood pressure was elevated by the electric stimulation of dorsal raphe nucleus in rats. Microinjection of 5-HT (6 micrograms, 3 micrograms) into habenular nucleus induced pressor effect too, but the heart rate was not much changed. Microinjection of procaine hydrochloride (300 micrograms.microliters-1) into both sides of habenular nuclei, the pressor effect induced by stimulation of dorsal raphe nucleus was alleviated obviously (85% blockade). The data suggested that habenular nucleus participates in the pressor effect caused by the excitation of dorsal raphe nucleus, and 5-HT may be one of the neurotransmitters in the action of habenular nucleus participating in cardiovascular regulatory function.