Dietary Cystine Ameliorates Defects in Spermatogenesis via Testosterone Production Induced by Protein Deficiency and Darkness in Rats.

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.

Effect of Dietary Protein Levels on Protein Nutritional Status in Growing Female Rats Kept under Constant Darkness.

The purpose of this study was to clarify the effects of dietary protein levels on protein nutritional status in rats kept under constant darkness. Thirty-six 4-wk-old female rats (F344 strain) were divided into six groups. Each group was given a diet with one of three different protein levels and kept under normal light and dark cycles (7:00-19:00 light period/19:00-7:00 dark period, N group) or under constant darkness (D group) for 4 wk. The protein levels of the diets were 10%, 20%, and 30% casein. The six groups are referred to as the N10%, N20%, N30%, D10%, D20%, and D30% groups. Body weight gain was low in the D groups, and that in the D30% group was much lower than that in the N30% group. The D30% group retained less nitrogen than the N30% group. As for the amount of urinary nitrogen excreted every 4 h, the values for the D-groups were higher than those for the N-groups in the 11:00-15:00 periods, and that for the D30% group was higher than that for the N30% group in the 15:00-19:00 periods, which means that protein catabolism was higher in the D30% group. It was shown that when rats kept under constant darkness were fed a high-protein diet for 4 wk, their nitrogen retention decreased and their protein nutritional state dropped.

Comparison of the effects of dietary protein on the sexual organ development of male mice and rats kept under constant darkness.

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 interactive effect of dietary water-soluble vitamin levels on the depression of gonadal development in growing male rats kept under disturbed daily rhythm.

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 the effects of nine water-soluble vitamins. We selected 7 water-soluble vitamins (choline, nicotinic acid (NA), pantothenic acid (PA), vitamin B6 (VB6), vitamin B1 (VB1), vitamin B2 (VB2) and folic acid (FA)) as experimental factors for the first experiment (Ex. 1) and biotin and vitamin B12 (VB12) as experimental factors for the second experiment (Ex. 2). The dietary content of these vitamins was normal or six times the normal content. Lighting condition (L.C.) was also added as a factor. Four-week-old male rats (Fischer 344 strain) were kept under constant darkness or normal lighting (12-h light/dark cycle) for 4 wk. The depression of gonadal development in the constant darkness groups (D-groups) was shown. The L.C., PA, VB6 and VB1 influenced testes development, and these three vitamins had interactions with L.C. Among the normal lighting groups (N-groups), the highest value for testes weight was observed under the normal-PA, high-VB6 and high-B1 diet; on the other hand, among the D-groups, it was observed under the high-PA, normal-VB6 and normal-VB1 diet. The results showed that the depression of gonadal development in rats kept under disturbed daily rhythm was improved by getting a high amount of PA and normal amount of VB6 and VB1.

Effect of dietary protein levels on sex hormones in growing male rats 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 interactive effect of dietary fat-soluble vitamin levels on the depression of gonadal development in growing male rats kept under disturbed daily rhythm. Investigations based on the L16(2¹5) type orthogonal array.

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 interactive effect of dietary protein and vitamin levels on the depression of gonadal development in growing male rats kept under disturbed daily rhythm.

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. The present study examined protein and vitamins, and their interactions. This study was based on three-way ANOVA; the three factors were lighting conditions, dietary protein and dietary vitamins, respectively. The levels of dietary protein were low or normal: 9% casein or 20% casein. The levels of dietary vitamins were low, normal or high: 1/3.3 of normal (AIN-93G diet) content, normal content, or three times the normal content, respectively. Other compositions were the same as those of the AIN-93G diet, and six kinds of experimental diet were prepared. 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. In the constant darkness groups (D-groups), the low-protein diet induced reduction of gonadal organ weights and serum testosterone concentrations. This reduction of gonadal organ weights was exacerbated by progressively higher levels of dietary vitamins. In the case of a normal-protein diet, the depression of gonadal development was not accelerated by high-vitamin intake. In the normal lighting groups (N-groups), the low-protein and high-vitamin diet slightly depressed gonadal development. These results suggest that the metabolism of protein and vitamins is different in rats being kept under constant darkness, and that excess dietary vitamins have an adverse effect on gonadal development in rats fed a low-protein diet.

The effects of calcium, phosphorus, magnesium, sodium, and zinc in improving the depression of gonadal development in growing male rats kept under a disturbed daily rhythm-investigations based on the L(16)(2(15))-type orthogonal array.

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.

Transcriptional coactivator p300/CBP-associated factor and p300/CBP-associated factor type B are required for normal estrogen response of the mouse uterus.

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 effects of nutrients in improving the depression of gonadal development in growing male rats kept under disturbed daily rhythm--investigations based on the L8(2(7)) type orthogonal array--.

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 L8(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.