Ligands for histamine H3 receptors modulate cell proliferation and migration in rat oxyntic mucosa

Abstract

1. (R)-α-methylhistamine, a selective agonist of histamine H3 receptors, promotes mucus secretion and increases the number and volume of mucus-secreting cells. The hypothesis that the increased number of mucous cells could reside in an alteration of homeostasis in the gastric epithelium was investigated. 2. (R)-α-methylhistamine was administered to rats 1 h (10-100 mg kg−1 by intragastric and by intraperitoneal route) and 24 h (100 mg kg−1 by intragastric route) prior to killing. The (S)-isomer of α-methylhistamine (55.4 mg kg−1), 100 times less potent than the (R)-isomer at H3 receptors, and the H3-receptor agonist FUB 407 (9.14-91.35 mg kg−1) were intragrastically administered 1 h prior to killing. The H1-receptor antagonist mepyramine (30mg kg−1), the H2-receptor antagonist famotidine (3 mg kg−1), and the H3-receptor antagonists ciproxifan (3 mg kg−1) and clobenpropit (30 mg kg−1) were intragastrically administered 30 min before (R)-α-methylhistamine. Gastric tissue was processed for histology and immunohistochemistry. 3. Within 1 h, (R)-α-methylhistamine and FUB 407 dose-dependently increased the number of BrdU-positive Cells and of apoptotic cells. (S)-α-methylhistamine failed to modify proliferation and apoptosis. The increase in proliferation by (R)-α-methylhistamine was reversed by ciproxifan and clobenpropit, but not by mepyramine and famotidine. 4. (R)-α-methylhistamine accelerated the differentiation towards pit cells and their outward migration 24 h after its administration. These effects were counteracted by ciproxifan. The apoptosis rate was unaffected at 24 h. 5. These findings reveal a primary role of histamine H3-receptor ligands in modulating cell proliferation and migration in rat fundic mucosa.