Effect of short-term starvation on reproductive hormone gene expression, secretion and receptor levels in male rats.
The effects of 4-6 days of food deprivation on the pituitary-testicular function of adult male rats were studied. Fasting decreased body weights on average by 23% (P less than 0.01) and those of seminal vesicles by 55% (P less than 0.01) in 4 days. No consistent changes were found in testicular and ventral prostate weights. The pituitary levels of gonadotrophin-releasing hormone (GnRH) receptors decreased by 50% (P less than 0.01). Serum and pituitary levels of LH, FSH and prolactin decreased by 25-50% (P less than 0.01 for all). Testicular and serum levels of testosterone decreased by 70-80%, testicular LH receptors by 26%, those of prolactin by 50% (P less than 0.01 for all), but those of FSH remained unaffected. Acute (2 h) stimulation by a GnRH agonist (buserelin, 10 micrograms/kg i.m.) resulted in similar LH, FSH and testosterone responses in the fasted and control animals, and human chorionic gonadotrophin (hCG) stimulation (30 IU/kg i.m.) in similar increases in testosterone. A 42% decrease was found in pituitary content of mRNA of the common alpha subunit (P less than 0.05), but the mRNAs of the LH- and FSH-beta chains and prolactin were unaffected by fasting for 4 days. When the same mRNAs were measured after 6 days of fasting, the decrease of the mRNA of FSH-beta also became significant (50%, P less than 0.01). In contrast, the mRNA of LH-beta was increased twofold (P less than 0.01) at this time and serum LH levels were similar in control and starved animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Bergendahl
M
M
Department of Physiology, University of Turku, Finland.
Perheentupa
A
A
Huhtaniemi
I
I
D000818:Animals; D006065:Gonadotropins, Pituitary / Q000502:physiology*; D008297:Male; D010902:Pituitary Gland / Q000503:physiopathology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D011967:Receptors, Gonadotropin / Q000032:analysis; D011966:Receptors, LHRH / Q000032:analysis; D013217:Starvation / Q000503:physiopathology*; D013737:Testis / Q000503:physiopathology*; D013739:Testosterone / Q000502:physiology*; D013997:Time Factors
D006065:Gonadotropins, Pituitary; D012333:RNA, Messenger; D011967:Receptors, Gonadotropin; D011966:Receptors, LHRH; D013739:Testosterone