Insulin-induced hypoglycemia does not impair the surge of luteinizing hormone secretion in the proestrous rat.
To know whether insulin-induced hypoglycemia (IIH), which has been shown to inhibit pulsatile luteinizing hormone (LH) secretion, also affects the surge of LH secretion, adult female rats were injected with insulin (5 units/rat) or saline intravenously at 1300 or 1600 h on the day of proestrus and serum concentrations of LH and blood glucose were determined during the period from 1100 to 2100 h. The injection of insulin at neither 1300 nor 1600 h affected the surge of LH secretion, but it significantly decreased the blood glucose. Together with our recent hypothesis that the pulsatile and surge of LH secretion are controlled by separate gonadotropin-releasing hormone (GnRH) mechanisms, we conclude that the GnRH surge generator is less sensitive to IIH than the GnRH pulse generator.
Kawaguchi
M
M
Department of Physiology, Yokohama City University School of Medicine, Yokohama, Japan.
Funabashi
T
T
Kimura
F
F
D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D005260:Female; D007003:Hypoglycemia / Q000097:blood* / Q000139:chemically induced; D007328:Insulin / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D011359:Proestrus / Q000097:blood*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin; D007986:Luteinizing Hormone