Studies of gastrin and gastric secretion in the horseSandin, Andreas
The high frequency of gastric ulcers in horses and the lack of information about the mechanisms that regulate gastric acid secretionformthe basis for this thesis. The research work was undertaken to characterise horse gastrin and to study the secretions of gastrin and acid in horses.
The amino acid sequence of horse gastrin G 17 and G 34 differs from other species in several respects. In particular, horse gastrin contains a lysin instead of a glutamic add in the acidic stretch of amino adds preceding the bioactive C-tenninal portion of the molecule, which makes the molecule less addic than in gastrins of other species. Determination ofthe cDNA indicatesthat horse preprogastrin contains three more amino adds than preprogastrins from other spedes. Horses do not express sulphated gastrins and probably lack the required enzyme system. In comparisonwith otherspecies a relatively large amount of G 34 is found in the horse antrum. Horse gastrins do not bind well to antibodies produced against human gastrin.
Gastrin release in horses seems to be little influenced by nervous excitation. Following local stimulation ofthe gastric antrum by a meal, a significant rise of the plasma gastrin concentration is found. A grainmeal produces a more prolonged gastrin release than a hay meal, possible due to the prolonged emptying ofthe grain meal from the stomach.
The synthesised horse gastrin 17 effectively stimulates the gastric acid output in horses, dogs and rats. Horses are extremely sensitive to histamine stimulation. Thus, dogs require 4-8 times more and rats 250-500 times more of histamine to produce maximal add secretion.
Nervous stimulation by teasing evokes a minute add response in horses. Insulininduced hypoglycaemia in contrast to most other spedes reduces the basal add output in the horse which is in contrast to the effed seen in other species. Basal horse gastric add secretion is stimulated by cholinergic stimulation.
KeywordsAtropine; bethanechol; cortisol; equine; gastric acid secretion; gastric cannula; gastrin; histamine; insulin; teasing; volume secretion
Published inActa Universitatis Agriculturae Sueciae. Veterinaria
1999, number: 69
Publisher: Swedish University of Agricultural Sciences
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