Selective enhancement of synaptic inhibition by hypocretin (orexin) in rat vagal motor neurons: implications for autonomic regulation.

摘要: The hypocretins (orexins) are hypothalamic neuropeptides implicated in feeding, arousal, and autonomic regulation. These studies were designed to determine the actions of hypocretin peptides on synaptic transmission dorsal motor nucleus vagus nerve (DMV). Whole-cell patch-clamp recordings made from DMV neurons transverse slices rat brainstem. Some identified as gastric-related by retrograde labeling after inoculation stomach wall with pseudorabies virus 152, a viral label that reports enhanced green fluorescent protein. Consistent previous findings, caused an inward current (6–68 pA) most at holding potentials near rest. In addition, frequency spontaneous IPSCs was increased concentration-related manner (up 477%), little change EPSCs. This effect preserved presence tetrodotoxin, suggesting presynaptic site action. Hypocretins amplitude evoked electrical stimulation tractus solitarius (NTS) but not Hypocretin-induced increases photoactivation caged glutamate within NTS also observed. Identical effects observed unlabeled neurons. contrast some studies, which have reported primarily excitatory many regions CNS, these data support role for preferentially enhancing inhibition, including inhibitory inputs arising NTS. findings indicate can modulate coordinate visceral output acting directly central vagal circuits.