The Effect of Adrenalectomy and Cortisone Supplementation on Caries Incidence in Caries-susceptible Rats

Effect of low-dose glucocorticoid treatment on dentin formation and dentinal caries in rats

The effect of a low dose of glucocorticoids on dentin formation and progression of dental caries was studied in young rats. The animals were inoculated in the mouth with Streptococcus sobrinus and fed ad libitum a high-sucrose, a high-starch, or a reference diet. The cortisone or placebo pellet was implanted subcutaneously in the back of the necks of the animals. After a 6-week experimental period the areas of dentin formation and dentinal caries were quantified planimetrically. Schiff's staining was used to classify caries. Cortisone reduced the dentin formation both in high-starch and reference diets, but it did not further affect the reducing effect of the high-sucrose diet on dentin formation. Cortisone did not affect the number or severity of dentinal carious lesions.

Regulation of parotid salivary proteins by glucocorticoids

Previous studies have indicated that adrenal-intact rats treated for one week with pharmacological doses of the synthetic glucocorticoid, dexamethasone, show a significant reduction in the proportion of proline-rich proteins and an increase in the proportion of amylase in rat parotid saliva (Johnson et al., 1987). In order to understand more fully the role of glucocorticoids in the regulation of salivary proteins, we performed bilateral adrenalectomies on groups of rats. Some of the adrenalectomized rats were treated with replacement-level doses of the synthetic glucocorticoid, dexamethasone. The food intake was monitored daily for both groups, and sham-operated pair-fed controls were included so that the effects of alterations of food intake could be separated from those of the experimental procedures. After eight to 12 days, uniformly stimulated parotid saliva was collected from these animals as well as from sham-operated controls fed ad libitum. The volume of saliva collected in 30 min was recorded, and the saliva samples were analyzed for concentration and composition of protein. Although the volume of saliva was not affected, parotid saliva collected from adrenalectomized rats exhibited a two-fold greater proportion of proline-rich proteins and reductions in other major secretory proteins: DNase, Fraction I, and Fraction V. The parotid gland secretory granules of adrenalectomized rats were more electron-lucent than in the ad libitum-fed controls. Treatment of adrenalectomized rats with dexamethasone largely prevented the changes in salivary protein composition as well as the alterations in secretory granule morphology.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of some contraceptive steroids on growth and development of salivary glands and incidence of dental caries in female rats

Synthetic contraceptive steroids, ethynylestradiol and medroxyprogesterone acetate, were given individually in different doses to weanling female rats for eight weeks. In proportion to the doses administered, ethynylestradiol inhibited and medroxyprogesterone acetate stimulated the growth and development of the salivary glands. The steroid-treated rats exhibited an increase in dental caries incidence as compared to controls.

Influence of corticosterone on the integrity of salivary glands and the incidence of dental caries in the rat

Intact weanling rats were given daily subcutaneous injections of 1.0 mg, 2.0 mg, or 3.0 mg of corticosterone or 0.5 mg of hydrocortisone acetate for 11 weeks. All hormone treatments resulted in a significant decrease in weight and tubular diameter of the submandibular gland. A significant increase in caries incidence was observed in all the hormone-treated rats, except those receiving 1.0 mg of corticosterone. Although corticosterone caused a decrease in thyroid gland weight, the protein-bound iodine (PBI) levels of the treated rats were normal. This indicated that corticosterone-induced increase in caries incidence and interference with the salivary gland integrity were not due to the decreased thyroid function.

Influence of some steroid contraceptives on icidence of dental caries and changes in salivary glands in female rats

The synthetic steroid contraceptives, norethynodrel and mestranol, were injected subcutaneously beginning at weanling or pubertal age, into female rats. With increased doses of steroid(s), the caries incidence proportionally increased and with increased frequency of administration and duration of treatment, the total cariogenic dose of the steroid(s) decreased by 95%. A synergistic, or at least an additive, cariogenic effect existed between the two steroids. Absolute and relative salivary glandular weights decreased and increased, respectively, on administration of the steroid. Both the diameter of and relative number of submandibular granular tubules decreased as compared with those of the controls.

Effect of hydrocortisone acetate on dental caries and salivary glands in adrenalectomized female rats

Adrenalectomized rats were given 0.5 mg or 1.0 mg of hydrocortisone acetate once daily for eight weeks. With increased hormonal doses, the dental caries activity and salivary glandular weights proportionally increased and decreased, respectively, as compared with adrenalectomized controls. Adrenalectomized rats had less dental caries than sham-operated rats. Either adrenalectomy or hormonal treatments interfered with the absolute weights, and especially with the histologic integrity of the salivary glands, in comparison with sham-operated rats.