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 L16(215)-Type Orthogonal Array

Abstract

SummaryThe 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 L 16 ( 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 Interactive Effect of Dietary Fat-Soluble Vitamin Levels on the Depression of Gonadal Development in Growing Male Rats Kept under Disturbed Daily Rhythm

“…We have already reported that serum testosterone concentrations were decreased by keeping rats under constant darkness (5)(6)(7)(8) and also by feeding them a low-protein diet ( 5 , 8 ), and the reduction of gonadal organ weight appeared to be caused by the decreased serum testosterone concentration. The dietary vitamin level, when the level was from 1/3 of normal to 3 times the normal level, had no effect on the serum testosterone concentration ( 8 , 9 ).…”

“…5 Colecalciferol, 400,000 IU/g. 6 DL-␣ -Tocopherol Acetate, 25 IU/g. 7 Soluble phylloquinone in soybean oil (0.2 mg/g soybean oil).…”

The Interactive Effect of Dietary Protein and Vitamin Levels on the Depression of Gonadal Development in Growing Male Rats Kept under Disturbed Daily Rhythm

“…7 Having different lower-case letters within a column means a significant difference of at least 95% probability for protein levels. 8 Having different italic letters within a column means a significant difference of at least 95% probability for vitamin levels. 9 * p <0.05, ** p <0.01.…”

The Interactive Effect of Dietary Water-Soluble Vitamin Levels on the Depression of Gonadal Development in Growing Male Rats Kept under Disturbed Daily Rhythm

“…5 Diluted with mannitol to 1,000 times. 6 Diluted with sucrose to 10 times. 7 Diluted with sucrose to 100 times.…”

“…In previous papers, we have reported the effects on rat gonadal development of protein, methionine, vitamins, minerals and oil (5), minerals (6), amino acids, an AIN-76 diet and an AIN-93G diet (7), the interaction between protein and vitamins (8), water-and fat-soluble vitamins (9) and each of the fat-soluble vitamins (10). We have demonstrated that a high level (three times the normal (AIN-93G)) of water-soluble vitamin and a low level (1/3.3 of normal) of fat-soluble vitamin diet mitigated the depression of gonadal development in rats kept under constant darkness (9).…”