Computer vision-based diameter maps to study fluoroscopic recordings of small intestinal motility from conscious experimental animals

Fluoroscopic Characterization of Colonic Dysmotility Associated to Opioid and Cannabinoid Agonists in Conscious Rats

Background/Aims

Gastrointestinal adverse effects have a major impact on health and quality of life in analgesics users. Non-invasive methods to study gastrointestinal motility are of high interest. Fluoroscopy has been previously used to study gastrointestinal motility in small experimental animals, but they were generally anesthetized and anesthesia itself may alter motility. In this study, our aim is to determine, in conscious rats, the effect of increasing doses of 2 opioid (morphine and loperamide) and 1 cannabinoid (WIN 55,212-2) agonists on colonic motility using fluoroscopic recordings and spatio-temporal maps.

Methods

Male Wistar rats received barium sulfate intragastrically, 20–22 hours before fluoroscopy, so that stained fecal pellets could be seen at the time of recording. Animals received an intraperitoneal administration of morphine, loperamide, or WIN 55,212-2 (at 0.1, 1, 5, or 10 mg/kg) or their corresponding vehicles (saline, Cremophor, and Tocrisolve, respectively), 30 minutes before fluoroscopy. Rats were conscious and placed within movement-restrainers for the length of fluoroscopic recordings (120 seconds). Spatio-temporal maps were built, and different parameters were analyzed from the fluoroscopic recordings in a blinded fashion to evaluate colonic propulsion of endogenous fecal pellets.

Results

The analgesic drugs inhibited propulsion of endogenous fecal pellets in a dose-dependent manner.

Conclusions

Fluoroscopy allows studying colonic propulsion of endogenous fecal pellets in conscious rats. Our method may be applied to the noninvasive study of the effect of different drug treatments and pathologies.

Preclinical evaluation of the effects on the gastrointestinal tract of the antineoplastic drug vincristine repeatedly administered to rats

BACKGROUND

Vincristine is a commonly used chemotherapeutic agent. It is associated with undesirable digestive side effects. However, the impact of vincristine on gastrointestinal structure and motility or its long-term effects have not been deeply studied in animal models. This could be useful in order to develop therapeutic or preventive strategies for cancer patients. The aim of this study was to analyze such effects.

METHODS

Rats received saline or vincristine (0.1 mg kg^-1 , ip) daily for 10 days. Evaluations were performed during treatment and 2-6 weeks after. Somatic mechano-sensitivity was assessed using von Frey hairs. Gastrointestinal motor function was studied by means of radiographic still images and colonic propulsion of fecal pellets using fluoroscopy videos. Histological assessment of the gut morphology and immunohistochemistry for HuC/D and nNOS were performed in whole-mount myenteric plexus preparations.

KEY RESULTS

Peripheral sensitivity was increased in animals treated with vincristine and did not subside 2 weeks after treatment finalization. Vincristine treatment inhibited gastrointestinal motility although this was recovered to normal values with time. Damage in the digestive wall after vincristine treatment was greater in the ileum than in the colon. Villi shortening (in ileum) and large inflammatory nodules still remained 2 weeks after treatment finalization. Finally, the proportion of nNOS-immunoreactive neurons was increased with vincristine and continued to be increased 2 weeks after treatment finalization.

CONCLUSIONS AND INFERENCES

Vincristine alters gastrointestinal motility, peripheral sensitivity and mucosal architecture. Vincristine-induced neuropathy (somatic and enteric), intestinal mucosa damage and inflammatory infiltrations are relatively long-lasting.