Brain–gut interactions between central vagal activation and abdominal surgery to influence gastric myenteric ganglia Fos expression in rats

Abstract

We previously showed that medullary thyrotropin-releasing hormone (TRH) or the stable TRH agonist, RX-77368 administered intracisternally induces vagal-dependent activation of gastric myenteric neurons and prevents post surgery-induced delayed gastric emptying in rats. We investigated whether abdominal surgery alters intracisternal (ic) RX-77368 (50 ng)-induced gastric myenteric neuron activation. Under 10 min enflurane anesthesia, rats underwent an ic injection of saline or RX-77368 followed by a laparotomy and a 1-min cecal palpation, or no surgery and were euthanized 90 min later. Longitudinal muscle/myenteric plexus whole-mount preparations of gastric corpus and antrum were processed for immunohistochemical detection of Fos alone or double labeled with protein gene-product 9.5 (PGP 9.5) and vesicular acetylcholine transporter (VAChT). In the non surgery groups, ic RX-77368 induced a 17 fold increase in Fos-expression in both gastric antrum and corpus myenteric neurons compared to saline injected rats. PGP 9.5 ascertained the neuronal identity of myenteric cells expressing Fos. In the abdominal surgery groups, ic RX-77368 induced a significant increase in Fos-expression in both the corpus and antrum myenteric ganglia compared with ic saline injected rats which has no Fos in the gastric myenteric ganglia. However, the response was reduced by 73–78% compared with that induced by ic RX 77368 without surgery. Abundant VAChT positive nerve fibers were present around Fos positive neurons. These results indicate a bidirectional interaction between central vagal stimulation of gastric myenteric neurons and abdominal surgery. The modulation of gastric vagus-myenteric neuron activity could play an important role in the recovery phase of postoperative gastric ileus.

Central administration of pan-somatostatin agonist ODT8-SST prevents abdominal surgery-induced inhibition of circulating ghrelin, food intake and gastric emptying in rats

“…20 Although vagal cholinergic antiinflammatory mechanisms have also been involved in normalizing postoperative ileus, 29 these are taking place mainly during the immunogenic phase (starting 3 h post surgery). 29 The short time frame (within 50 min) of present postoperative gastric ileus studies favors the vagal re-activation of enteric muscarinic pathways inhibited by surgery 58 as the predominant mechanism of the i.c. ODT8-SST action consistent with the neurogenic phase occurring during the first hour post surgery.…”

Thyrotropin releasing hormone (TRH) in the brainstem: Role of Pavlov’s vagally mediated cephalic phase of gastric secretion

“…Additionally, RX-77368 injected intracisternally, at a dose that stimulates efferent activity in the gastric branch of the vagus ( fig. 2A), activates 90% of submucosal and myenteric cholinergic neurons located in the gastric corpus and antrum in rats (Miampamba et al 2001;2011;Yuan et al 2005). This was demonstrated in conscious rats by double immunostaining of gastric enteric neurons with Fos, the nuclear marker of synaptic activation and PGP 9.5, a neuronal marker (Krammer et al 1993), or peripheral acetyl cholinergic transferase (Yuan et al 2005) ( fig.…”

Gastric motor dysfunction coincides with the onset of obesity in rats fed with high‐fat diet

“…In a separate group, rats were killed by cervical dislocation under isoflurane anaesthesia. Gastric tissues were removed and placed in a dissecting dish containing phosphate buffered saline (PBS, pH 7.4) containing nifedipine (10 −6 mol/L) to avoid muscle contraction, 35 opened along the small curvature and greater curvature. After the tissues were then pinned and stretched on a Petri dish containing Sylgard with the mucosal side facing up, they were incubated and fixed in 4% paraformaldehyde (PFA) for 18–24 hours at 4°C.…”

“…The images were captured using a fluorescent microscope equipped with appropriate filters for secondary antibodies. Cuprolinic blue staining was performed as previously reported 35,37 to quantify number of the fundic and antral myenteric neurons. The LMMP preparations were rinsed in distilled water and stained 2 hours at 42°C with Cuprolinic blue (0.3% quinolinic phthalocyanine in 0.05 mol/L sodium acetate‐1.0 mol/L magnesium chloride buffer, pH 4.9).…”