外侧臂旁核神经元对穹窿下器逆向刺激和孤束核顺向剌激的反应

Responses of neurons in lateral parabrachial nucleus to antidromic stimulation of subfornical organ and to orthodromic stimulation of nucleus tractus solitarius in the rat]

Single unit discharges were extracellularly recorded from the neurons in the lateral parabrachial nucleus (LPBN) and responses of the recorded units to antidromic stimulation of the subfornical organ (SFO) and to orthodromic stimulation of the nucleus tractus solitarius (NTS) were observed in urethane-anesthetized rats. Following electrical stimulation of the SFO, 9.9% (51/151) of the LPBN units were antidromically activated. After activation of peripheral baroreceptors by raising arterial blood pressure with an intravenous injection of phenylephrine, 40.7% (22/54) of the LPBN units were inhibited and 27.8% (17/54) excited. Following orthodromic stimulation of the depressor area in the NTS, 55.6% (94/169) of the LPBN units showed an increase and 22.5% (38/169) a decrease in firing rates. Among the LPBN neurons antidromically activated by SFO stimulation, 2 units were inhibited by phenylephrine administrated i.v.; of the 8 units tested, when the NTS was stimulated, 6 were excited and 2 inhibited. The results suggest that the LPBN neurons may receive inhibitory or excitatory baroreceptive inputs from the NTS and then relay it directly to SFO.