Visceral Hypersensitivity and Altered Colonic Motility in Type 2 Diabetic Rat

Abstract

Background/Aims Abnormal visceral sensitivity and disordered motility are common in patients with diabetes mellitus. The purpose of the present study was to investigate whether visceral sensation and bowel motility were altered in a rat model of type 2 diabetes mellitus accompanied by weight loss. Methods A type 2 diabetic rat model in adulthood was developed by administrating streptozotocin (STZ; 90 mg/kg, i.p.) to neonatal rats. Eight weeks after STZ administration, rats with blood glucose level of 200 mg/dL or higher were selected and used as diabetic group (n = 35) in this study. Abdominal withdrawal reflex and arterial pulse rate were measured to examine visceral nociception induced by colorectal distension (0.1–1.0 mL). The amplitude, frequency, and area under the curve (AUC) of spontaneous phasic contractions of colonic circular muscles were recorded in vitro to examine colonic motility. Results STZ-treated diabetic rats gained significantly less weight for 8 weeks than control ( P < 0.01). Forty-eight percent of the diabetic rats showed enhanced visceral nociceptive response to colorectal distension. Diabetic rats did not differ from control rats in colorectal compliance. However, the frequency and AUC, not the amplitude, of colonic spontaneous contraction in vitro was significantly decreased in diabetic rats compared to control rats ( P < 0.01 in frequency and P < 0.05 in AUC). Conclusions These results demonstrate visceral hypersensitivity and colonic dysmotility in a rat model of type 2 diabetes mellitus accompanied by weight loss.

Combined Administration of Streptozotocin and Sucrose Accelerates the Appearance of Type 2 Diabetes Symptoms in Rats

“…In our research, we found that 90 mg of STZ induced the majority of the characteristics of diabetes (hyperglycemia, low body weight gain, and polyphagia) in both males and females; in fact, this dose is widely used [9, 15, 25, 30, 31]. However, its implementation in this research is difficult as a study model due to that it promotes high mortality in animals.…”

Alpha-lipoic Acid suppresses P2X receptor activities and visceral hypersensitivity to colorectal distention in diabetic rats

“…Several abnormal gastrointestinal conditions are studied, including disturbed motility and abnormal sensation 23 , 24 . Visceral hypersensitivity is one of the important pathological manifestations.…”

Diabetes-induced mechanophysiological changes in the small intestine and colon

“…Colon (Table 3 ): Colonic dysmotility is often seen in DM patients[ 85 , 91 - 97 ] and animal models[ 97 - 103 ]. DM patients with DAN are expected to have delayed transit in the entire gut, this finding is apparent to some extent in the distal colon but not in the proximal colon[ 92 ].…”

“…Touw et al[ 108 ] showed that Type 1 DM is associated with decreased depolarization-induced Ca(2+) influx in colonic smooth muscle, leading to attenuated myosin light chain phosphorylation and impaired colonic contractility. Sung et al[ 103 ] showed that the frequency, not the amplitude, of colonic spontaneous contraction in vitro was significantly decreased in DM rats compared to control rats. However, enhanced contractility of the colon in the DM animals has also been reported[ 109 , 110 ].…”

“…The hypersensitivity was associated with an enhanced neuronal excitability of primary sensory neurons that showed an up-regulated expression of voltage-gated sodium channels (VGSCs, i.e ., NaV1.7 and NaV1.8 subunits). Visceral hypersensitivity is also demonstrated in a rat model of type 2 DM accompanied by weight loss[ 103 ].…”