Food restriction, refeeding, and gastric fill fail to affect emesis in musk shrews

Abstract

Horn CC, Still L, Fitzgerald C, Friedman MI. Food restriction, refeeding, and gastric fill fail to affect emesis in musk shrews. Am J Physiol Gastrointest Liver Physiol 298: G25-G30, 2010. First published November 5, 2009 doi:10.1152/ajpgi.00366.2009.-Nausea and emesis are common side effects of gastrointestinal disease. Reports indicate that ghrelin and endocannabinoids, agents that stimulate appetite, also reduce emesis evoked by chemotherapy treatment, which suggests that stimulation of feeding inhibits the emetic system. In the following study we conducted a more direct test of this hypothesis by determining the impact of manipulating the motivation to eat on emesis, using food restriction and refeeding. Emesis was induced in musk shrews, a commonly used animal model for emesis research, using the cancer chemotherapy agent cisplatin (20 mg/kg ip), nicotine (2 mg/kg sc), or motion (1 Hz, horizontal, 4-cm displacement), because these treatments are known to target separate emetic pathways: gut vagal afferents, area postrema, and vestibular pathways, respectively. Twenty-four hours of food restriction was sufficient to stimulate food intake, and 1 h of refeeding filled the stomach. The results indicate that food restriction, refeeding, and gastric fill had no significant effects on the amount of emesis produced by any of the emetic treatments tested here. This suggests that, although activation of the emetic system might have prominent effects on food intake, neural controls for feeding behavior do not significantly affect the neural pathways for emesis. These results may have implications for how we treat patients who experience a constellation of side effects, including nausea and emesis, since stimulating appetite may not necessarily inhibit emetic pathways.

Computerized detection and analysis of cancer chemotherapy-induced emesis in a small animal model, musk shrew

“…Cisplatin treatment at these doses produced an emetic intensity and pattern that was consistent with other reports (e.g., Andrews et al, 2000; Horn et al, 2010b; Kwiatkowska et al, 2004; Matsuki et al, 1988; Mutoh et al, 1992; Sam et al, 2003). The computer algorithm was largely successful for the detection of emetic episodes in the short-term (up to 24 h).…”

“…An emetic episode was recognized as a sequence of contractions of the abdomen and head movements (retching). An emetic episode can occur with or without the expulsion of gastric contents (Horn et al, 2010b) and, therefore, episodes without expulsion were also counted. The Observer software allows users to slow down, reverse, and check the coding of behaviors stored in a computer file containing the codes and timestamps.…”

“…In recent years, there has been an increased focus on the use of small animal models in emesis research, particularly musk shrews ( Suncus murinus ) (e.g., Horn et al, 2010b; Parker et al, 2009; Percie du Sert et al, 2010; Yamamoto et al, 2009). Notably rodents, including mice and rats, lack a vomiting response (Andrews and Horn, 2006; Andrews, 1995; Horn et al, 2010a).…”

Novel dynamic measures of emetic behavior in musk shrews

“…2 and 3 for emetic episodes with versus without vomiting are reliable. Feeding and gastric fill do not affect the total number of emetic episodes produced by motion exposure or injection of nicotine (or the chemotherapy agent cisplatin) in musk shrews (Horn et al, 2010). …”

Musk shrews selectively bred for motion sickness display increased anesthesia-induced vomiting

“…Emetic tests were conducted with a 3 to 4 week time interval between tests to allow for recover (test order: motion, nicotine, CuSO 4 , and then isoflurane) [32, 33]. Animals were tested between 0800 and 1200 h (light phase).…”