Gastrointestinal system emetics

The gastrointestinal system of zebrafish presents clear differences from the human system. The zebrafish does not possess a stomach, the intestine is continuous with the pharynx through a short esophagus, and no sphincters are present [61]. However, zebrafish have most of the cell types observed in the small intestine -absorptive, endocrine, goblet, and interstitial cells of Cajal, although Paneth cells are absent. Gut contractions are under the control of the enteric nervous systems, which respond to different pharmaceuticals in similar way as the mammalian counterpart. For example, zebrafish embryos can be used as predictor of emetic response to pharmaceuticals, one of the most commonly reported clinical adverse effects to be considered in the development of new dmgs [61]. 

In most patients, the ergot alkaloids have little or no significant effect on bronchiolar or urinary smooth muscle. The gastrointestinal tract, on the other hand, is quite sensitive. Nausea, vomiting, and diarrhea may be induced even by low doses in some patients. The effect is consistent with action on the central nervous system emetic center and on gastrointestinal serotonin receptors. 

Increased plasma concentrations cause ergot poisoning (ergotism, St Anthony s fire - dementia, florid hallucinations and persistent vasospasm gangrene may develop) and uterine muscle stimulation (it may cause abortion in pregnancy). Ergot alkaloids activates gastrointestinal serotonin receptors and central nervous system emetic centres. 

ANTIMUSCARINICS ANTI EMETICS - DOMPERIDONE, METOCLOPRAMIDE 1 efficacy of domperidone on gut motility by antimuscarinics Some effects of metodo-pramide are considered to be due to T release of ACh and T sensitivity of the cholinergic receptors to ACh. Antimuscarinics prevent the effects on muscarinic receptors The gastrointestinal effects of metodopramide will be impaired, while the antiemetic effects may not be. Thus, concurrent use with antimuscarinics is not advised because of effects on the gastrointestinal system... 

Primarily effects on the gastrointestinal system. These include decreased bowel motility and decreased gastric acid secretion. It is also believed that there is a vestibular component to the emetic action of opiate drugs. 

Syrup of ipecac is available as a nonprescription product in many countries. It is derived from the dried rhizome and roots of the Cephaelis ipecacuanha or Cephaelis acuminata plant. These plants contain the potent emetic alkaloids emetine and cephaeline, which induce vomiting by both direct local gastrointestinal effects and central nervous system actions. Emesis following syrup of ipecac ingestion typically occurs within 20 min of ingestion and persists for 30-120 min. 

It is interesting that emesis can be induced in other vertebrate animals upon intravenous inoculation of SE (Clark, et ah, 1962). Although this is a well documented response, this activity probably does not directly reflect the action of the toxins in the gastrointestinal tract. Other PTs which are not associated with food poisoning, such as TSST-1, cause an emetic response when they gain access to the systemic circulation (Bohach, et al., 1990). In fact, gastrointestinal abnormalities are commonly observed in patients with TSS. The most likely explanation for this phenomenon is that it is a consequence of the multiorgan effect of the toxins linked to their role in this disease. 

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