Acute fasting is ineffective in suppressing pituitary-gonadal function of pubertal male rats.
Effects of short-term fasting (3-4 days) on pituitary-testicular functions were studied during sexual maturation in male rats at 25, 35, 45, 55, and 65 days of age. Among the main findings, testicular testosterone decreased by 41-68% at all ages (P < 0.01-0.05). The pituitary steady-state mRNA levels of the common alpha-subunit (28-55%) and follicle-stimulating hormone (FSH) beta-subunit (25-50%) decreased (P < 0.01-0.05) at 25, 55, and 65 days of age but not at 35 and 45 days; the luteinizing hormone (LH) beta-subunit did not respond at any age. Fasting decreased serum LH (P < 0.01) at 25, 55, and 65 days of age but not at 35 and 45 days. Likewise, fasting decreased pituitary and/or serum FSH only in the 25- and 65-day-old rats (P < 0.01-0.05). In conclusion, LH and FSH secretion, and the gene expression of common alpha- and FSH beta-subunits, decreased consistently during short-term fasting only in prepubertal (25 days) and adult (65 days) but not in peripubertal animals (35 and 45 days). Hence, the pubertal rise in gonadotropins represents such a strong positive induction that it largely overrides the antigonadotropic effect of fasting.
Bergendahl
M
M
Department of Physiology, University of Turku, Finland.
Huhtaniemi
I
I
D000818:Animals; D001835:Body Weight; D015342:DNA Probes; D005215:Fasting / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000235:genetics / Q000378:metabolism; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics; D007986:Luteinizing Hormone / Q000097:blood / Q000235:genetics / Q000378:metabolism; D008297:Male; D009929:Organ Size; D010902:Pituitary Gland / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012669:Seminal Vesicles / Q000254:growth & development / Q000502:physiology*; D012741:Sexual Maturation / Q000502:physiology*; D013737:Testis / Q000254:growth & development / Q000502:physiology*; D013739:Testosterone / Q000097:blood / Q000378:metabolism
D015342:DNA Probes; D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D012333:RNA, Messenger; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone