Poitras P, Trudel L, Miller P, Gu C M
Centre de Recherche Clinique André-Viallet, Hôpital Saint-Luc, Université de Montréal, Canada.
Am J Physiol. 1997 Jan;272(1 Pt 1):G4-9. doi: 10.1152/ajpgi.1997.272.1.G4.
The regulatory process of motilin release was studied in segments of canine jejunum isolated and perfused ex vivo. The secretion of motilin in the effluent venous system of the isolated intestine was measured by radioimmunoassay in response to various pharmacological agents injected intra-arterially. Muscarinie agonist and antagonist, respectively, increased and decreased the release of motilin. The stimulatory effect of carbachol was still documented after tetrodotoxin (10(-5) M) was injected in the system to block neural influence on M cells. Bombesin and morphine also increased the release of motilin. The effect of bombesin was still documented in the presence of atropine or tetrodotoxin, but the stimulatory morphine effect was blocked by atropine. Both phenylephrine and octreotide decreased the release of motilin stimulated by carbachol in a jejunal segment pretreated and denervated with tetrodotoxin. Therefore, a revised model for the regulation of motilin release from M cells of intestinal mucosa can now be proposed. Cholinergic and bombesin receptors are present on M cells to encode a stimulatory signal, whereas adrenergic and somatostatin receptors are responsible for inhibitory transmission. The stimulatory effect of morphine is mediated via a muscarinic transmitter.
采用离体灌注的犬空肠段研究胃动素释放的调节过程。通过放射免疫分析法测定离体肠流出静脉系统中胃动素的分泌，以响应动脉内注射的各种药理剂。毒蕈碱激动剂和拮抗剂分别增加和减少胃动素的释放。在系统中注射河豚毒素（10⁻⁵ M）以阻断神经对M细胞的影响后，仍记录到卡巴胆碱的刺激作用。蛙皮素和吗啡也增加胃动素的释放。在阿托品或河豚毒素存在的情况下，仍记录到蛙皮素的作用，但吗啡的刺激作用被阿托品阻断。在预先用河豚毒素处理并去神经的空肠段中，去氧肾上腺素和奥曲肽均降低了由卡巴胆碱刺激的胃动素释放。因此，现在可以提出一个关于从肠黏膜M细胞调节胃动素释放的修订模型。胆碱能和蛙皮素受体存在于M细胞上以编码刺激信号，而肾上腺素能和生长抑素受体负责抑制性传递。吗啡的刺激作用是通过毒蕈碱递质介导的。
