Fasting portal vein plasma levels of gastric inhibitory polypeptide (GIP) and extractable fasting GIP in the duodenal wall in rats treated with methylprednisolone or alloxan compared with normal controls.
Ten rats were treated with methylprednisolone, another 10 rats with alloxan, and a final 10 control rats with saline. Compared with the controls, the methyl-prednisolone-treated rats had increased fasting levels of serum insulin, blood glucose, and plasma GIP; the alloxan-treated rats had decreased fasting levels of insulin and increased levels of fasting blood glucose and plasma GIP. After removal of the duodenum in the fasting state, the amount of GIP was measured in duodenal tissue specimens after extraction with ice-cold acetic acid, pH 3.0, and with neutralized acetic acid at 95 C. The duodenal content of GIP was 765.5 +/- 60.2 ng/g in the methylprednisolone-treated rats, 897.6 +/-37.3 ng/g in the alloxan-treated rats, and 923.1 +/- 72.9 ng/g in the saline-treated control rats. There were no significant differences in duodenal GIP content between the various groups, nor did the fasting plasma GIP and the amount of duodenal GIP in the individual rats correlate significantly (r=0.147, p less than 0.1). The elevated levels of fasting plasma GIP in the diabetic rats treated with methylprednisolone or alloxan may be due to factors regulating the secretion of GIP rather than to changes in the duodenal content of GIP.
D000496:Alloxan / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism*; D004386:Duodenum / Q000378:metabolism*; D005749:Gastric Inhibitory Polypeptide / Q000097:blood / Q000378:metabolism*; D005768:Gastrointestinal Hormones / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D008297:Male; D008775:Methylprednisolone / Q000494:pharmacology*; D011169:Portal Vein; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D005768:Gastrointestinal Hormones; D007328:Insulin; D005749:Gastric Inhibitory Polypeptide; D000496:Alloxan; D008775:Methylprednisolone