Histamine H3 receptors are not involved in the regulation of rat gastric secretion.
The effects of histamine H3 receptor activation [(R)alpha-methylhistamine] and blockade (thioperamide) on rat gastric secretion were determined in vivo and in vitro. (R)alpha-Methylhistamine (0.1-5 mumol/kg i.p.) did not modify secretory volume and acidity in pylorus-ligated rats; it did not affect basal acid secretion and the secretion stimulated by histamine, pentagastrin and 2-deoxy-D-glucose in the lumen-perfused stomach of anaesthetized rats, when administered by continuous infusion (0.01-1 mumol/kg/h) or bolus injection (0.05-25 mumol/kg). In this preparation, the H3 agonist increased acid secretion at doses of 3-25 mumol/kg i.v., the effect being antagonized by famotidine. In the isolated gastric fundus from immature rats both (R)alpha-methylhistamine (0.01-10 mumol/l) and thioperamide (0.01-1 mumol/l) were totally ineffective against both spontaneous and stimulated gastric secretion. These results suggest that histamine H3 receptors are unlikely to have a role in regulating gastric acid secretion in the rat.
Coruzzi
G
G
Institute of Pharmacology, University of Parma, Ospedale Maggiore, Italy.
Adami
M
M
Bertaccini
G
G
D000818:Animals; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism*; D008761:Methylhistamines / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D008761:Methylhistamines; D010880:Piperidines; C052075:thioperamide