A. Bado et al., H-3 RECEPTOR REGULATION OF VASCULAR GASTRIN AND SOMATOSTATIN RELEASESBY THE ISOLATED RAT STOMACH, The Yale journal of biology & medicine, 67(3-4), 1994, pp. 113-121
We have studied the effects of the H-3-receptor agonist (R)alpha-methy
lhistamine [(R)alpha-MeHA] and the H-3-receptor antagonist thioperamid
e (Thiop) on basal- and carbachol-stimulated vascular gastrin release
(GR) and somatostatin release (SR) by the isolated rat stomach. Carbac
hol dose-dependently stimulated and inhibited GR and SR, respectively.
Maximal stimulation of GR (500 +/- 112 percent of basal; p < .01), an
d maximal inhibition of SR (-62 +/- 9 percent under basal; p < .01) we
re obtained with 1 mu M carbachol. Neither (R)alpha-MeHA nor Thiop, up
to 10 mu M, affected GR. However, SR was dose-dependently enhanced by
Thiop (25 +/- 8 percent for 10 mu M). Carbachol stimulation of GR was
strongly inhibited by Thiop (30 +/- 7 percent for 100 nM and 73 +/- 1
4 percent for 1 CIM), whereas it was potentiated by (R)alpha-MeHA. Car
bachol inhibition of SR was reversed by Thiop and (R)alpha-MeHA. Howev
er, the reversal effect of (R)alpha-MeHA was prevented by the CCKB/gas
trin receptor antagonist PD134308. These results support H-3-receptor
regulation of basal and cholinergically-stimulated GR and SR.