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Nutrition and light-dark cycle influence rat testicular development. With 9% casein diet (low protein diet) under normal 12 h-12 h lighting cycles (9P), juvenile rat testes undergo normal growth. On the other hand, a low protein diet with constant darkness (D9P) results in a growth arrest of rat testes. Supplementation of cystine to the low protein diet under constant darkness (D9PC) had a tendency to increase testes weight, suggesting an improvement in growth suppression. Whether the growth suppression of testes in D9P is associated with suppression of spermatogenesis has not yet been shown. We aimed to determine the effect of a low protein diet and constant darkness with or without dietary cystine in testes using a histological technique. In the histological assessment, D9P testes showed a decreased number of seminiferous tubules with elongated spermatids, indicating a functional testicular defect in this group. However, cystine supplementation resulted in enhanced spermatogenesis versus control animals (D9PC vs. D9P) implying the importance of cystine to testicular development in this condition. Furthermore, serum testosterone concentration was increased in D9PC suggesting contribution of testosterone to ameliorate spermatogenesis. From these results, we conclude that cystine supplementation to a low protein diet under constant darkness promoted an increase in testosterone which in turn benefitted spermatogenesis.

The purpose of this study was to determine whether the effects of dietary protein on sexual organ development were different in mice and rats kept under constant darkness. Four-week-old mice (ICR strain) and rats (F344 strain) were kept under constant darkness (D) or normal lighting (N; 12-h light/dark cycle) for 4 wk. The dietary protein level was 9% casein with the addition of 0.135% cystine (9PC) or without it (9P); other components of the diet were based on the AIN-93G diet. The testes and epididymides weights (g/100 g BW) of the rats given the 9P diet in the D-group were lower than those of the rats given the 9P diet in the N-group. In the mice, lighting conditions and diet did not affect testes or epididymides weights. Body weight and food intake in the rats were affected by diet, and these values were lower in the 9P diet group; however, body weight and food intake in the mice was not affected by diet. The serum albumin concentration in the rats was lower in the 9P diet group, while that of the mice was lower in the 9PC diet group. In the rats kept under constant darkness, a diet lacking in cystine accelerated the suppression of sexual organ development and decreased serum albumin concentration, but this diet had no such effects on the mice. The finding that the effects of dietary protein were different in mice and rats suggests that protein requirements of mice are different from those of rats.

The purpose of this study was to clarify the effects of nutrients on the gonadal development of male rats kept under constant darkness as a model of disturbed daily rhythm. In the present study we examined fat-soluble vitamins and their interactions in this test population. Four fat-soluble vitamins (vitamin A (V.A), vitamin D (V.D), vitamin E (V.E) and vitamin K (V.K)) were selected as experimental factors, and the dietary content of these vitamins was normal (AIN-93G) or three times the normal content. Lighting conditions (constant darkness or normal lighting) were also added as a factor. Four-week-old rats (Fischer 344 strain) were kept under constant darkness or normal lighting (12-h light/dark cycle) for 4 wk. The lighting condition and V.E, and the interactions between the lighting condition and V.E and between V.A and V.D were observed to affect the testes and epididymides weights. There was an influence of the lighting condition only on the seminal vesicles and prostate weights and the serum testosterone concentration. Among the constant darkness groups (D-groups), the highest value for testes weight was observed under the normal-V.A, normal-V.D and high-V.E diet. The interaction between lighting condition and V.E showed the testes weight increased slightly in response to changing to a high-V.E diet from a normal-V.E diet under normal lighting (N-group) but was greatly increased in response to this change in the D-group. It became clear that the amount of dietary V.E necessary for the gonadal development of rats increases when rats are kept under constant darkness.

The purpose of this experiment was to clarify the effects of dietary protein levels on the gonadal development and sex hormones in male rats kept under constant darkness as a model of disturbed daily rhythm. Four-week-old male rats (Fischer 344 strain) were kept under constant darkness or normal lighting (12-h light/dark cycle). Two kinds of experimental diet were prepared, one with low dietary protein levels (9% casein) and one with normal levels (18% casein). Harper mineral mixture and Panvitan were used as mineral and vitamin sources, respectively. After 4 weeks, gonadal weight, serum testosterone, and other hormone contents were evaluated. The gonadal weight in the constant darkness groups (D-groups) was lower than that in the normal lighting groups (N-groups). Although the low-protein diet in the D-groups significantly reduced gonadal weight, the normal-protein diet mitigated the reduction of gonadal weight in rats kept under constant darkness. Serum testosterone and androstenedione concentrations were lower in D-group rats fed the low-protein diet. There were no effects of lighting condition or protein levels on serum luteinizing hormone (LH), follicle- stimulating hormone (FSH), or progesterone concentrations. These results indicate that the suppression of gonadal development in D-group rats fed the low-protein diet was caused by low testosterone, which we attribute to the inhibition of synthesized androstenedione, a precursor of testosterone. The present study showed that constant darkness and the low- protein diet inhibited the synthetic pathway from progesterone to androstenedione.

The purpose of this study was to clarify the effects of nutrients on the gonadal development of male rats kept under constant darkness as a model of disturbed daily rhythm. In the present study we examined fat-soluble vitamins and their interactions in this test population. Four fat-soluble vitamins (vitamin A (V.A), vitamin D (V.D), vitamin E (V.E) and vitamin K (V.K)) were selected as experimental factors, and the dietary content of these vitamins was normal (AIN-93G) or three times the normal content. Lighting conditions (constant darkness or normal lighting) were also added as a factor. Four-week-old rats (Fischer 344 strain) were kept under constant darkness or normal lighting (12-h light/dark cycle) for 4 wk. The lighting condition and V.E, and the interactions between the lighting condition and V.E and between V.A and V.D were observed to affect the testes and epididymides weights. There was an influence of the lighting condition only on the seminal vesicles and prostate weights and the serum testosterone concentration. Among the constant darkness groups (D-groups), the highest value for testes weight was observed under the normal-V.A, normal-V.D and high-V.E diet. The interaction between lighting condition and V.E showed the testes weight increased slightly in response to changing to a high-V.E diet from a normal-V.E diet under normal lighting (N-group) but was greatly increased in response to this change in the D-group. It became clear that the amount of dietary V.E necessary for the gonadal development of rats increases when rats are kept under constant darkness.

We studied the extent of kidney calcification by varying dietary levels of Mg, based on pathological examinations and calcium (Ca) and magnesium (Mg) balance tests. AIN-76 diets containing varying levels of Mg--0.3 (-M), 1.3 (1/20M), 2.4 (1/10M), 9.2 (1/5M), 19 (control), 38 (2M), 102 (5M), and 187 (10M) mmol/kg diet--were fed to 3-week-old male Fischer-344 rats for 14d. Although the magnitude of abnormality was highest in kidney of rats fed the -M diet, the damage was normalized as the dietary level of Mg increased, with increasing serum Mg concentration and urinary excretion of Mg. We found almost no deposition of Ca in rats fed the 10M diet. The mechanism by which the high dietary Mg induces these effects most likely involves a competition between Mg and Ca for reabsorption in proximal and/or distal tubules, since these diets increased the urinary excretion of Ca. However, these high Mg diets decreased food intake and body weight gain compared with the control diet, although these indices were not decreased in rats fed the 2M diet. The results suggest that a dietary magnesium level approximately twice the normal level effectively reduces kidney calcification while maintaining normal growth in rats.

Mice with targeted gene disruption of one of the estrogen receptor coactivators, p300/CBP-associated factor (PCAF), and its counterpart, PCAF-B, were used to investigate the possible involvement of PCAF and PCAF-B in estrogen receptor-mediated actions in vivo. Among ovariectomized mice that were treated with estrogen, PCAF and PCAF/PCAF-B knockouts showed abnormal growth of the uterus compared with the wild type. The level of c-fos gene expression in the uterus was not induced by estrogen in the knockouts. These observations suggest that PCAF and PCAF-B are required for estrogen-dependent normal growth of the uterus via estrogen receptor-mediated transcriptional regulations.

The purpose of this study was to clarify the effects of nutrients on the gonadal development of male rats kept under constant darkness as a model of disturbed daily rhythm. This experimental protocol was designed based on the L16(2(15))-type orthogonal array, which can examine six factors. Five minerals (calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), and zinc (Zn)) were selected as experimental factors, and the dietary content of these minerals was normal (AIN-76 diet) or 1/3.5 of the normal content. Lighting conditions (constant darkness or normal lighting) were also added as a factor. Four-week-old rats (Fischer 344 strain) were kept under constant darkness or normal lighting (12-h light/dark cycle) for 4 wk. After 4 wk, the gonadal weights and serum testosterone content were evaluated. The lighting condition, Ca, Mg, and Na, and the interactions between the lighting condition and Ca, and Mg and Na were observed to affect the testes weight. Among the constant darkness groups (D-groups), the highest value for testes weight was observed under the normal-Ca, normal-Mg, and normal-Na diet, and the lowest value was observed under the low-Ca, normal-Mg, and low-Na diet. Among the normal lighting groups (N-groups), the highest value for testes weight was observed under the low-Ca, normal-Mg, and normal-Na diet, and the lowest value was observed under the normal-Ca, normal-Mg, and low-Na diet. Among the D-groups, the highest value for serum testosterone was observed under the normal-Ca, normal-Mg, and low-Na diet. Among the N-groups, the highest value was observed under the low-Ca, normal-Mg, and low-Na diet. It became clear that the amount of dietary Ca necessary for the gonadal development of rats increases when rats are kept under constant darkness as a model of disturbed daily rhythm compared with the normal lighting condition.

The purpose of this experiment was to clarify the effects of nutrients on the gonadal development of male rats kept under constant darkness as a model of disturbed daily rhythm. Protein, methionine, vitamins, minerals and fat were selected as experimental factors, and eight kinds of diets were prepared based on the L 8 (2 7 ) type orthogonal array Dietary contents of the nutrients were normal (AIN-76 diet) or 1/3 to 1/2 of the normal content. Four-week-old rats (Fischer 344 strain) were kept under constant darkness for 4 wk. Control groups were kept under 12-h light/dark cycle. After 4 wk, the gonadal weights and serum testosterone content were evaluated. The effects of nutrients on gonadal development in rats differed between constant darkness groups (D-groups) and normal lighting groups (N-groups). Among the D-groups, the highest value for testes weight was observed under the normal protein, methionine added, low vitamin, low mineral and normal fat diet. The lowest value for testes weight was observed under the low protein, methionine added, normal vitamin, normal mineral and low fat diet. Among the N-groups, the highest value for testes weight was observed under the normal protein and no methionine diet, and the lowest value was observed under the low protein and no methionine diet. Among the D-groups, the highest value for serum testosterone was observed under the normal protein and low mineral diet. In the N-groups, serum testosterone was not affected by nutritional factors. It became clear that the amounts of protein, methionine, vitamins. minerals, and oil which are necessary for the gonadal development of growing male rats change when kept in constant darkness.

The bioavailability of roasted and ground soybean (kinako) magnesium (Mg) in Fischer 344 strain male rats with respect to serum Mg level, bone Mg contents, kidney calcification, and Mg absorption was evaluated. Four-week-old male rats were divided into four groups of six rats each. The four groups were the control (20SC), Mg-deficient diet (1/3 Mg20SC), 20SCK diet, and 20SCDK diet. The 20SCK and 20SCDK diets were prepared to contain amounts of Mg equal to that in the 20SC diet with kinako or defatted kinako as the Mg source, respectively. After a 4-week experimental period, rats were decapitated and blood serum, right femur, and right kidney were collected, and Mg, calcium (Ca), and phosphorus (P) concentration in those tissues were determined. The Mg balance was also investigated. The serum Mg concentration in the 1/3 Mg20SC group was half the level in the 20SC group, and the serum Ca concentration was higher than in the 20SC group, indicating apparent hypercalcemia. Serum Mg and Ca concentrations in the 20SCK and 20SCDK groups did not significantly differ from those in the 20SC group. Femur Mg concentration in the 1/3 Mg20SC group was lower than in the 20SC group. Femur Mg concentrations in the 20SCK and 20SCDK groups were lower than in the 20SC group, but significantly higher than in the 1/3 Mg20SC group. The kidney Ca concentrations in the 20SCK and 20SCDK groups were significantly higher than those in the 20SC and 1/3 Mg20SC groups, and there was also kidney calcification. These results indicated that kinako and defatted kinako Mg were used effectively as a serum and femur Mg source, but that kinako and defatted kinako carry a risk of kidney calcification when used as the only Mg source.