The effect of chronic consumption of paraoxon on basal and pentagastrin-stimulated gastric acid and pepsin secretion in rats

Paraoxon, an organophosphate metabolite of the insecticide parathion inhibits the enzyme, acetylcholinesterase (Achase). Organophosphates affect the heart, visual system, nervous system and muscles. In this present study, we investigate the effects of the chronic consumption of paraoxon on gastric acid and pepsin secretion in N-mari rats. This study was performed from April 2003 to May 2004 in the Physiology department of Baghiatalah University of Medical Sciences, Tehran, Iran. It was performed on three groups of female N-mari rats (10 /group) each weighing 200-250 g. The first group received 0.05 mg/kg/day paraoxon subcutaneously for one month. The second group received the same chronic doses of ethyl alcohol (96%) (solvent of paraoxon) and the third group (control) received no drugs. After tracheostomy and laparatomy, gastric secretions were collected with a tube via the duodenum. Pentagastrin (25 microg/kg, i.p.) was used as a gastric stimulator. Acid and pepsin secretions were measured by titration and the Anson method, respectively. The stages of the measurements were basal (first and second), stimulated and returned-basal. Basal acid secretion in the paraoxon group was greater than those in the alcohol and control groups (14.61 +/- 1.46, 7.18 +/- 0.28 and 7.88 +/- 0.26 micromol/15 min, respectively, P < 0.001)). Although pentagastrin-stimulated acid secretion in all the three groups was greater than that of the basal state, there were no significant differences among the three groups. Basal pepsin secretions in the paraoxon group were greater than those in the alcohol and control groups (2.97 +/- 0.32, 1.19 +/- 0.25 and 0.55 +/- 0.06 microg/15 min, respectively). Pentagastrin-stimulated pepsin secretion in the paraoxon group was significantly greater than those in the alcohol and control groups (3.22 +/- 0.38, 2.22 +/- 0.46 and 1.09 +/- 0.66 microg/15 min, respectively, P < 0.001). Chronic exposure to paraoxon results in the increased secretion of gastric acid and pepsin.