Effects of long-term vitamin D deficiency and response to vitamin D repletion in the mature and aging male and female rat.
This study investigated the sex- and age-related alterations in calcium homeostasis in 39- to 82-week-old rats raised from weaning on a vitamin D deficient (-D) diet. It was found that vitamin D deprivation decreased the life span of male, but not female, rats. Female -D animals exhibited a steady increase in serum calcium with age from 39 to 82 weeks, although circulating calcium of -D animals never reached normocalcemic levels. There was no attenuation of the secondary hyperparathyroidism. Serum calcium of -D males was significantly lower than that of age-matched females at all ages when sufficient males were alive to make the comparison. Serum parathyroid hormone levels were decreased in -D females when serum calcium was elevated to hypercalcemic levels by calcium injection. Similarly, administration of vitamin D3 or 1,25-dihydroxyvitamin D3 elevated serum calcium and depressed parathyroid hormone in 14- and 22-month-old -D females. These animals also exhibited increased intestinal calcium binding protein content. Administration of vitamin D3 or dihydroxyvitamin D3 repaired renal adenylate cyclase refractoriness to parathyroid hormone. The sex- and diet-related alterations in serum phosphorus that were found at earlier ages disappeared by 67 weeks of age. Serum calcitonin was elevated in mature and aging +D males and females and -D females relative to younger animals. In -D males, calcitonin levels were less markedly elevated. The results of this study indicate that there are several important sex differences related to the regulation of calcium homeostasis in mature and aging rats. In addition, it was found that mature (14 month) and old (22 month) chronically -D female rats were able to respond to repletion with dihydroxyvitamin D3 or vitamin D within 10 days.
D000375:Aging / Q000187:drug effects; D000818:Animals; D002116:Calcitonin / Q000097:blood; D002117:Calcitriol / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood*; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002762:Cholecalciferol / Q000627:therapeutic use*; D005260:Female; D008136:Longevity / Q000187:drug effects; D008297:Male; D010710:Phosphates / Q000097:blood; D051381:Rats; D012737:Sex Factors; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy
D002135:Calcium-Binding Proteins; D010710:Phosphates; D002762:Cholecalciferol; D002116:Calcitonin; D002117:Calcitriol; D002118:Calcium