CCK mediated the inhibitory effect of oxytocin on the contraction of longitudinal muscle strips of duodenum in male rats

Abstract

The aim of the present study was to investigate the effect of oxytocin (OT) on duodenum motility in rats and the possibility that cholecystokinin (CCK) was involved in this process. The isometric contraction of longitudinal muscle strips of duodenum was monitored by polygraph. ELISA was used to measure the concentration of CCK and OT in duodenum. CCK mRNA was assayed by RT-PCR. Oxytocin receptor (OTR) and CCK in duodenum were located by immunohistochemistry and immunofluorescence staining. OT (10⁻⁵ and 10⁻⁶ M) inhibited the spontaneous contraction of the muscle strips. On the contrary, atosiban (OT receptor antagonist), lorglumide (CCK₁ receptor antagonist), and tetrodotoxin (TTX, blocker of voltage-dependent Na(+) channel on nerve fiber) excited the contraction. The inhibitory effect of OT on duodenal motility was reversed by pretreatment of atosiban, lorglumide, or TTX. Exogenous OT did not influence the expression of OT mRNA in duodenum but increased the concentration of CCK in the culture medium of the cells isolated from longitudinal muscle myenteric plexus. The OTR and CCK were co-expressed in the neurons of the myenteric plexus in duodenum. We concluded that OT inhibited the contraction of the LD spontaneous contraction of rats in vitro. This effect was mediated by the CCK released from the neurons of the myenteric plexus in duodenum.

Oxytocin hyperpolarizes cultured duodenum myenteric intrinsic primary afferent neurons by opening BKCa channels through IP3 pathway

“…Oxytocin appears to reduce motility in isolated muscle strips (Xie et al. 2006; Lv et al. 2010), but for the intact colon it enhances peristalsis (Ohlsson et al.…”

“…We have shown that OTR are expressed on myenteric neurons in rat duodenum, and that OT inhibits spontaneous neuronally dependent contractions of longitudinal muscle strips in vitro (Lv et al. 2010).…”

Oxytocin-induced membrane hyperpolarization in pain-sensitive dorsal root ganglia neurons mediated by Ca2+/nNOS/NO/KATP pathway

“…Oxytocin receptor (OTR), a member of the G-proteincoupled receptor family, is distributed in the brain and peripheral tissues (Gimpl and Fahrenholz, 2001;Kimura et al, 2003;Lv et al, 2010;Viero et al, 2010;Boccia et al, 2013). It is known that the OTR is expressed in the dorsal root ganglia (DRG), principally in non-peptidergic C-fiber cell bodies (Moreno-Lopez et al, 2013).…”

The Enteric Network: Interactions between the Immune and Nervous Systems of the Gut

“…This infection causes upregulation of CCK and 5-HT expression in EECs, both of which are implicated in hypophagia (Burton-Freeman et al, 1999; Hayes et al, 2006). Furthermore, CCK and IL-4 induce contractions in the longitudinal muscle (Lv et al, 2010; Zhao et al, 2003), and increased contractibility of the GI tract is associated with T. spiralis expulsion (Vallance et al, 1997). Interestingly, prior T. spiralis infection increases sensitivity of mouse enteric neurons to T. spiralis antigens, and this heightened sensitivity is abrogated by histamine receptor antagonism (Frieling et al, 1994).…”