| Abstract: | Extracellular unitary recordings were made from neurons in the rat dorsal vagal nucleus, and the response of these neurons to iontophoretically applied cholecystokinin octapeptide (CCK-OP) and proglumide (a novel CCK antagonist) was studied. The effect of CCK-OP and proglumide on the response of the neurons to gastric distension was also studied. Seventy-four percent (n = 39) of the neurons studied were excited by CCK-OP. It was not possible to antagonize the response to CCK-OP with proglumide. CCK-OP was also found to be an effective modulator of the response to gastric distension; the effects were diverse ("on" responses were augmented; "off" and "transient" responses were diminished) but were always the same within each characteristic pattern of response to distension. These results provide supporting evidence for CCK-OP, a peptide common to both brain and gut, acting in the role of a neural modulator in the control of the gastrointestinal tract. It is possible to speculate that the potent effect of CCK-OP on neuronal excitability and on the central representation of gastric mechanoreceptor activity may well substantiate the role of CCK-OP as a central regulator of feeding behavior. |
