Gossypol acetic acid administered orally at 30 mg/kg body weight/day for five weeks inhibited the fertility of male rats without an apparent loss of libido. Sperm in the ejaculate were rendered immotile and were reduced in number. Serum testosterone and LH were reduced significantly from pretreatment values, whereas FSH values were not altered. Leydig cells from treated animals produced less testosterone than did control Leydig cells when incubated with LH. Furthermore, testosterone production by normal Leydig cells that were incubated with LH and gossypol was inversely related to gossypol concentration. Ultrastructural examination of epididymal spermatozoa revealed degeneration in the tail region, particularly in the mitochondrial sheath of the middle piece. Within the seminiferous epithelium, late spermatids displayed a similar degeneration, although not as severe. After a six-week recovery period, normal fertility was re-established and normal litters were produced. Sperm motility and number, serum testosterone and LH levels, and sperm structure all returned to normal.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.1939-4640.1981.tb00615.x

Effects of Gossypol on the Reproductive System of Male Rats

The function of the hypothalamic-pituitary-testicular axis was evaluated in rats fed a low protein diet for 4 weeks beginning at 21 days of age. Compared to control, the low protein group had decreased seminal vesicle and prostate weights as well as decreased testicular testosterone output in vitro, although serum testosterone was not different. The low protein group showed no consistent alterations in serum LH (basal, post-LHRH, and postcastration) compared to control although serum FSH (basal and post-LHRH) was lower in the low protein group. Despite this lower basal FSH, the low protein group had supranormal serum FSH after castration. Seminiferous tubule diameter and testicular histology were normal in the low protein group although testicular androgen-binding protein was absent. Testicular androgen-binding protein was also undetectable in a modestly food-restricted control group which had normal testicular size, testicular histology, androgen output, and serum FSH. This finding suggests that loss of testicular androgen-binding protein may be a sensitive sign of undernutrition. We conclude that rats fed a low protein diet have hypoandrogenism, normal testicular histology, and supranormal FSH after castration despite subnormal basal FSH. The latter combination suggests overproduction of an FSH inhibitor of testicular origin.

Hypoandrogenism and abnormal regulation of gonadotropin secretion in rats fed a low protein diet

A study was conducted to explore the hypothesis that reduced caloric intake increases the negative feedback efficacy of testosterone on gonadotropin secretion. Daily subcutaneous injections of testosterone propionate in oil were administered to either age-matched (37-day-old) or weight-matched (mean = 178 g) ad libitum-fed (control) or underfed rats that received 60% of normal daily food intake from the age of 20 days. Daily doses of testosterone propionate ranged from 25 to 400 micrograms/100 g body weight. Results indicate that reduced caloric intake increases the suppression of serum LH by testosterone propionate in both age-matched and weight-matched underfed rats. On the other hand, the response of serum FSH concentrations to testosterone propionate was affected by reduced diet only in the weight-matched animals. Results suggest that the increased negative feedback of testosterone on LH secretion is a specific diet-induced effect and not merely the result of reduced growth. The altered response in FSH secretion, however, may represent age-associated changes in sensitivity to testosterone rather than diet-induced effects.

Altered Testosterone Feedback in Pubertal Male Rats Raised on Reduced Caloric Intake

Male weanling rats were fed four diets providing high or low levels of protein and/or zinc. One group on each diet was sacrificed every 2 weeks to measure the weights of the reproductive organs, plasma levels of follicle-stimulating hormone and luteinizing hormone, and the plasma and testicular concentrations of testosterone, dihydrotestosterone and zinc. The results demonstrate that hypogonadal states are produced in response to protein deficiency and zinc deficiency but the mechanisms involved are different. The specific effects of zinc deficiency are not observed in protein-deficient animals.

Response of the reproductive system of male rats to protein and zinc deficiency during puberty.

Either quantitative or qualitative modification of diet interferes markedly with the reproductive functions of the rat. The effect of chick mash or cowpeas (Vigna unquiculata) on body growth, accessory sex organ weights, serum testosterone, and epididymal histology was studied. Body growth was markedly decreased in cowpeas fed group. Binucleated, multinucleated giant cells (MGCs), and lymphocytes were found in large numbers in the lumen of caput and cauda epididymis of the cowpea-fed group. No noticeable effect was seen in chick mash-fed group. Serum testosterone levels were significantly decreased in cowpea-fed group. Presence of MGCs in cowpea-fed animals indicates epididymal dysfunction and probably renders them infertile.

https://www.tandfonline.com/doi/pdf/10.3109/01485019208987708

A. B. Kar

Papers

Effect of protein deficiency on genital organs and fertility of male rats.

Protein synthesis in the testis of protein-deficient rats. Effect of gonadotrophic hormone & testosterone propionate.