Development Of Submandibular Gland Research Articles

Effects of chemical sympathectomy on postnatal development of the rat submandibular gland

Temporary chemical sympathectomy was accomplished by daily injection of the catecholamine-depleting agent, reserpine, for the first six days of life. The rat pups were then allowed to mature, and their submandibular glands (SMG) sequentially examined by light and electron microscopy. Reserpine retarded SMG development by about two weeks when compared to saline-treated litter-mates. One day after the end of reserpine treatment, glands appeared rudimentary, similar to those of newborns. With age the glands matured, and seven weeks after treatment (eight weeks of age), there were few structural differences between glands from experimental or control animals. In a separate experiment, 12 newborn rats were treated with reserpine for six days and then allowed to mature to 12 weeks. Three developed an obstructive sialadenitis. Several experiments were run to see if this lesion could be replicated. Only three of 36 more animals developed sialadenitis, so its induction was neither consistent nor reproducible.

Thyroidal modulation of androgenic expression in mice submandibular gland.

We investigated the influence of testes and thyroid gland on the maintenance of biochemical parameters and of [3H]R1881 binding sites of adult mice submandibular gland (SMG). Castration (Cx) performed at beginning of puberty prevented sex-dependent SMG development without interfering with maximal androgen binding capacity. Thyroidectomy (Tx) had strong effects on SMG, mainly by lowering the number of androgen binding sites. All alterations could be fully reverted after treatment with testosterone (5 mg/animal, single dose) or with thyroxine (T4, 250 micrograms/animal per day during 5 days). The effects of Cx on SMG could be reverted by therapy with testosterone, T4, or with both hormones (testosterone + T4) in a non-synergistic fashion. It is shown the importance of thyroidal activity on the physiological maintenance of androgen receptors in the murine SMG; the role played by thyroid gland seems to be essential for the full expression of the androgen-dependent SMG activity in adult mice.

Increased mastication and submandibular gland development in the rat

1. 1. The effects of increased mastication on submandibular gland development were studied in immature Sprague-Dawley rats, 32 days old. 2. 2. Increased mastication had no effect on body wt, submandibular gland weight or acinar cell size. 3. 3. DNA, RNA, protein, peroxidase and an androgen-dependent alkaline protease were unaffected by increased mastication. 4. 4. Alkaline protease, a product of the granular convoluted tubules, was greater in male than in female rats. 5. 5. Conversely, peroxidase activity which is of acinar cell origin was greater in the submandibular glands of female animals.

The effects of lights of different spectra on caries incidence in the golden hamster

Golden hamsters, exposed to fluorescent light which simulated both the visible and ultraviolet spectra of natural outdoor light, had one-fifth as many caries as animals exposed to conventional fluorescent light. Total body, gonad and submandibular gland weights were greater for the animals raised under the simulated natural light. Differences in gonad and submandibular gland development were histologically demonstrated with haematoxylin and eosin stained sections. Thus, light affected caries incidence, submandibular gland development and sexual maturity.

Effect of progesterone on growth and delopment of submandibular glands in female rats.

Progesterone in daily doses of 0.6 mg or 1.5 mg/100 gm body weight was given subcutaneously to weanling female rats for ten weeks. Controls were treated similarly with a vehicle. At the low dose level, progesterone did not affect body and gland growth in comparison to the controls. However, at the high dose level, progesterone stimulated the body growth and the growth and development of submandibular glands.

Effect of norethindrone on submandibular glands and dental caries in female rats.

The effect of prolonged administration of norethindrone on the growth and development of submandibular glands and on the incidence of dental caries in rats was studied. Weanling female Sprague-Dawley strain rats were divided randomly into groups and were given daily subcutaneous injections of 30 60 or 90 mcg of norethindrone in .1 ml of steroid diluent for 9 or 14 weeks. Norethindrone in different dose levels caused in general a slight increase in wet weight and a significant increase in the diameter and relative number of granular tubules and in the sizes of acinar cells of submandibular glands. No significant changes in parotid gland weight were observed. Norethindrone in different dose levels caused an increase in the incidence of carious lesions but no differences in severity of carious lesions were observed between norethindrone treated groups of rats and their controls.

Relationship between insulin and growth hormone in growth and development of rat submandibular glands.

SummaryAlloxan diabetes mellitus was induced in weanling female Sprague-Dawley strain rats. Diabetics in the test groups were given daily subcutaneous injection of 1 U of protemine zinc insulin (PZI), 50 or 100 μg of growth hormone (GH) or 1 U of PZI plus 50 μg of GH/100 g of body weight for 14 days. Diabetic and intact controls were similarly treated with vehicle. A significant retardation of the growth of salivary glands was shown in the diabetics as compared to intact controls. In the diabetics, PZI treatment resulted in a significant stimulation and GH treatment in an inhibition of the growth of the salivary glands. PZI and GH administered concurrently exhibited a synergism in stimulating salivary gland growth.