Effect of short-term starvation on reproductive hormone gene expression, secretion and receptor levels in male rats

Abstract

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)

Effects of Starvation on Gonadotropin and Thyrotropin Subunit mRNA Levels and Plasma Hormone Levels in the Male Japanese Quail (Coturnix coturnix japonica)

“…We also showed that starvation induced decreases in mRNAs encoding the LHβ-, FSHβ-and common α-subunit precursor molecules in the Japanese quail. In the rat, it was reported that starvation had a suppressive effect on the levels of FSHβ and common α mRNAs and no effect on the level of LHβ mRNA in the pituitary gland (Bergendahl et al, 1989 andBergendahl and Huhtaniemi, 1993). In the sheep, it was reported that long-term food restriction had no effect on the levels of gonadotropin subunit mRNA while it decreased levels of plasma gonadotropins (Thomas et al, 1990).…”

“…A series of papers with such approach has been published for the rat (Bergendahl et al ., 1989 andBergendahl and Huhtaniemi, 1993), with a similar paper also on the sheep (Thomas et al ., 1990).…”

Caloric restriction: Impact upon pituitary function and reproduction

“…CR-induced suppression of the pulsatile release of GnRH from the hypothalamus is considered to be the central mechanism by which this reproductive perturbation occurs (Veldhuis et al, 1993;Cameron et al, 1991). It has been shown that GnRH receptor content (which is controlled by GnRH levels in the hypophyseal portal system) in the pituitary is sensitive to CR and fasting (Bergendahl et al, 1989;Greuenwald and Matusmoto, 1993). The resultant effects of short-term fasting, i.e.…”

The endogenous feeding suppressant, 2-buten-4-olide, impairs the pulsatile secretion of luteinizing hormone through endogenous opioid peptides

“…Reduced food intake is known to be associated with reproductive dysfunction in humans (1,2), and rats (3)(4)(5). Several kinds of endogenous sugar acids found in rat blood have been reported to be involved in control of food intake (6,7).…”

“…There are some reports (3)(4)(5) that fasting impairs the pulsatile secretion of LH and that the specific opioid antagonist, naloxone or naltrexone, reverses this impairment (12,13). Therefore, EOPs may be involved in the 2-B4O-induced decrement in LH secretion.…”