In vitro study of antral gastrin biosynthesis in response to weaning and corticosterone acetate in rats

Abstract

The effects of weaning (abrupt dietary changes from breast milk to solid food) and corticosterone injection on antral gastrin-like immunoreactivity (G-LI) concentrations and antral G-LI biosynthesis were studied in rats. A single dose of corticosterone acetate was injected in one group of 7 day old rats, and a single dose of physiological saline was injected in another. Each group of rats was divided into two subgroups, one fed only rat breast milk until 25 days old and the other weaned at day 21. Inn on-cor t i cost erone treated unweaned rats, antral G-LI did not increase. In non-corticosterone treated weaned rats, antral G-LI was constant before weaning, then increased 4-fold to the adult level. In corticosterone treated unweaned rats, the antral G-LI on day 11 was twice than on day 7, and thereafter remained constant.In corticosterone treated weaned rats, antral G-LI increased after corticosterone treatment and increased again after weaning to reach the adult level at day 25. Gel filtration of pulse-chase incubated antral samples with l-[methyl-3H]methionine from unweaned rats without corticosterone administration showed Vo, fraction 19 (Fr. 19) and gastrin-34 (G34) peaks, but no gastrin-17 (G17) peak after 60 min of chase incubation, but at 120 min of chase incubation a G17 peak was present; corticosterone-treated and/or weaned (solid food alone) rat samples showed Vo, Fr. 19, G34 and G17 peaks at 30 min of pulse incubation.Gastrin has been isolated in two chemically de¬ fined main forms: big gastrin (gastrin-34, G34) and little gastrin (gastrin-17, G17); G17 is thought to be derived from G34 (Walsh 1977; Dockray et al. 1978). However, the physiological mechanisms responsible for initiating gastrin biosynthesis are not well understood. Recent studies have shown that the antral gastrin concentration increases greatly when weaning is started (Lichtenberger & Johnson 1974; Takeuchi et al. 1981). Peitsch et al. (1981) demonstrated that in unweaned young rats corticosterone injection caused an increase in antral gastrin concentration. The present study was undertaken to evaluate the effect of weaning and corticosterone administration on antral gastrin-like immunoreactivity concentration and bio¬ synthesis in young rats. Material and MethodsThe effect ofdietary changes and corticosterone adminis¬ tration on antral gastrin-like immunoreactivity (G-LI) concentration (Study I) Animak. Male Wistar rats were reared in individual cages in a temparature-and light-controlled room ( 12 h dark and 12 h light). Rats aged 7 to 25 days and adult rats (350 g, 15 weeks old) were divided into six groups.Group 1 rats were injected with a single dose of isotonic saline (0.1 ml) sc on day 7 and were placed in a cage with a mother. They were allowed to suckle ad libitum, but were given no access to solid food until 21 days old, when weaning (dietary changes from breast milk to solid food) was started. The lactating mothers were changed every 12 h. Group 2 rats were treated with isotonic saline, as in group I, and received breast m...

Influence of Hydrocortisone on the Development of the Gastric Mucosa in Suckling Rats

“…A similar phenomenon was observed if the glucocorticoid treatment was given from the 7th day of life to suckling rats, i.e. 75 mg/kg/day of hydrocortisone for 6 days [8] or 250 mg/kg of corticosterone once [9,31], In the current study, we were able to confirm that the highest dose of hydrocortisone we used (40 mg/kg/day) in creased both antral gastrin content and con centration in treated pups over control val ues. The variations observed for antral gas trin concentration were roughly of the same order as previously noted: +104% [8] and + 142% (our data).…”

Secretion of acid, gastrin, and cobalamin‐binding proteins by the fetal pig stomach: developmental regulation by cortisol

“…Exogenous administration of corticosterone induces precocious development of acid, gastrin and cobalamin(vitamin Bl2)-binding protein (intrinsic factor) secretion in the rat stomach and the normal developmental changes at 2-3 weeks of age in the rat stomach occur in parallel with a surge in plasma glucocorticoid levels (Peitsch, Takeuchi & Johnson, 1981;Okahata, Nishi, Muraki, Sumii, Tanaka, Miyachi & Usui, 1986;Dieckgraefe, Seetharam & Alpers, 1988;Hilsted, Bardram & Rehfeld, 1988;Hervatin, Moreau, Ducroc, Garzon & Geleso, 1989). Glucocorticoid regulation of stomach development has not been demonstrated for species such as pig and man where considerable maturation of acid, gastrin and intrinsic factor secretion occurs in utero or in the neonatal period (Marino, Bacon, Hines & Halpin, 1984;Sangild, Cranwell & Hilsted, 1992a).…”

Influence of diet on the development of antral gastrin-like immunoreactivity in the stomach of rats

“…Chromatographie procedure Gel nitrations of antral samples from 25-day-old rats which received various nutrients in Groups 1-5 and adult rats were performed at 4°C on a Sephadex G-50 superfine column (1 X 55 cm) according to our previous methods (Okahata et al 1986). The elutions of G-LI in each sample were compared with elutions of blue dextran (Pharmacia Fine Chemicals, Uppsala, Sweden) (void volume, V"), human G17 and G34 of adult human antral extract and Na[125I] (total volume, V,) (Amersham Ine, Arlington Heights, IL).…”

“…No increase was observed during milk feeding alone. Gel filtration of antral gastrin-like immunoreactivity from 25-day-old rats on laboratory chow or three essential nutrients showed the same results.We have demonstrated that antral gastrin concen¬ trations of rats increase rapidly when weaning is started (Okahata et al 1985(Okahata et al a,b, 1986 and that the weaning increases gastrin-17 (G17) biosynthesis in rats (Okahata et al 1986). Our findings agree with other observations that antral gastrin-like immu¬ noreactivity (G-LI) increases after physiological weaning and more abruptly after laboratory chow intake alone (Lichtenbreger & Johnson 1974;Takeuchi et al 1981).…”

“…weaning increases gastrin-17 (G17) biosynthesis in rats (Okahata et al 1986). Our findings agree with other observations that antral gastrin-like immu¬ noreactivity (G-LI) increases after physiological weaning and more abruptly after laboratory chow intake alone (Lichtenbreger & Johnson 1974;Takeuchi et al 1981).…”