Leptin--a regulator of islet function?: its plasma levels correlate with glucagon and insulin secretion in healthy women.
It has previously been demonstrated that plasma leptin correlates to body fat content. It has also been demonstrated that in subjects with normal glucose tolerance, circulating leptin correlates to circulating insulin and to insulin secretion and that these relations are independent of body fat. However, whether leptin also covaries with other islet hormones is not known. We therefore studied the relation between plasma levels of leptin and glucagon secretion and circulating pancreatic polypeptide (PP) in healthy humans. Arginine was injected intravenously (5 g) at fasting and at 14 and 28 mmol/L, glucose in 71 postmenopausal women with normal glucose tolerance. In a multivariate analysis controlling for the influence of the body mass index, we found that circulating leptin correlated significantly to fasting insulin (r = .38, P = .002), and to circulating insulin at 14 mmol/L glucose levels (r = .29, P = .0019) and 28 mmol/L glucose (r = .32, P = .009), as well as to the insulin response to arginine at all three glucose levels (r > .30, P < .013). Circulating leptin, independently of the body mass index, also correlated to fasting glucagon (r = .31, P = .012) and to the glucagon response to arginine at all three glucose levels (r > .28, P < .038). In contrast, circulating leptin did not correlate to plasma glucagon at 14 or 28 mmol/L glucose or to plasma levels of PP. We conclude that circulating leptin correlates to the secretory capacity of both glucagon and insulin but not to the reduction of plasma glucagon during hyperglycemia or to PP in a large group of postmenopausal women. This suggests that islet function is related to circulating leptin in humans.
Ahrén
B
B
Department of Medicine, Lund University, Malmö, Sweden.
Larsson
H
H
D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D004305:Dose-Response Relationship, Drug; D005260:Female; D005934:Glucagon / Q000097:blood / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D005951:Glucose Tolerance Test; D006801:Humans; D006943:Hyperglycemia / Q000097:blood / Q000503:physiopathology; D007275:Injections, Intravenous; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000502:physiology*; D020738:Leptin; D008875:Middle Aged; D015999:Multivariate Analysis; D010191:Pancreatic Polypeptide / Q000097:blood; D017698:Postmenopause / Q000097:blood; D011506:Proteins / Q000032:analysis* / Q000378:metabolism / Q000502:physiology*; D012727:Sex Characteristics; D044465:White People
D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D011506:Proteins; D010191:Pancreatic Polypeptide; D005934:Glucagon; D001120:Arginine; D005947:Glucose