Inhibition of rat nucleus tractus solitarius neurones by activation of 5-HT2C receptors

In vivo, nucleus tractus solitarius (NTS) neurones receiving monosynaptic v agal input and inactive intermediate neurones were inhibited by both DOI an d a selective 5-HT2C receptor agonist, MK-212. Cells receiving a more polys ynaptic input were excited by DOI and although MK-212 also excited a few of these cells, the majority of cells in these groups were unaffected by MK-2 12. The inhibitory, but not the excitatory actions of both MK-212 and DOI w ere prevented by a selective 5-HT2C receptor antagonist, RS-102221. In cont rast, most dorsal vagal preganglionic neurones were unaffected by applicati on of either DOI or MK-212, the few remaining cells being excited by both a gonists. These data demonstrate that DOI-evoked inhibition of NTS cells act ivated by vagal afferent input and DOI-evoked excitation of vagal pregangli onic neurones is mediated by 5-HT2C receptors. NeuroReport 11:1785-1790 (C) 2000 Lippincott Williams & Wilkins.