Impaired salivary gland secretory function following the induction of rapid, synchronous vitamin A deficiency in rats.

Rapid and essentially synchronous vitamin A deficiency was induced by the withdrawal of retinoic acid from stringently deficient animals reared by feeding early weight plateau vitamin A-deprived male rats diets first supplemented with and then lacking in 2 micrograms retinoic acid/g diet in repeating 18:10 day cycles. Secondary inanition was minimized by the control led force-feeding of deficient and control animals. The time to inset of pilocarpine (3 mg/kg body weight) induced salivation increased progressively starting 6-8 days after retionate withdrawal. Concomitantly, saliva volumes in the 20 minutes following the onset of salivation decreased. Protein and alpha-amylase concentrations were constant until around days 10-12 (T10-12) of deficiency but then decreased. Synthesis of proteins was normal, however as judged by total parotid gland alpha-amylase activity (T14). Seemingly, vitamin A deficiency may directly affect cells involved in saliva secretion, since decreased secretory function was noted several days prior to keratinization and blockage of the striated and excretory ducts.