There is general acceptance of the view that the postnatal growth and development of many organ system is regulated in large measure by the extent of functional demand imposed.
In order to know the responses and mechanisms of submaxillary gland to changes in functional demands and surgical stress with in the oral cavity, the wet weight of the submaxillary gland of rats were measured and the histology was observed after following various procedures with or without the treatment of several drugs.
Surgical stress was applied by extraction of lower incisors, periodic ampution of erupted portion of lower incisors, and amputation of lower incisors of rats treated with several centrally acting drugs or autonomic blocking agents. Additional results were recorded following intramuscular injection of chymotrypsin, cold stress or ingestion of ginseng extracts.
Results are as follows.
1) A slight increase in fresh wet weight of submaxillary salivary gland was observed after a single or twice amputation of erupted portion of the lower unilateral incisors. The effect of amputation was largely but entirely restricted to the ipsilateral salivary glands.
However, 2 or 4 periodic amputations of lower bilateral incisors resulted in a marked increase in the wet weight as early as 4 to 8 days after the first amputation. Thus the effect of repeated amputations on the fresh wet weight of submaxillary salivary gland was increased by increasing the number of teeth amputated and the frequency of amputation, and by lengthening the period from the first amputation to autopsy. In histological observationst enlargement of both perous and mucous acini of submaxillary glands was observed by periodic amputation of lower incisors, but no effect on the formation of new acini or changes within the tubular cells could be detected. The intensity of enlargement of acini seemed to correlate with salivary gland weight.
2) The effect of 4 periodic amputations of lower bilateral incisors on the wet weight of the submaxillary salivary gland was decreased slightly but significantly by pulp capping with zinc-oxide and eugenol cement immediately after amputations.
3) The pulpectomy alone with minimal loss of enamel or dentin tissues of lower bilateral incisors resulted in a slight but statistically significant increase in the wet weight of the submaxillary glands.
4) After unilateral extraction of lower incisors, a slight increase in wet weight of the submaxillary gland and a profound decrease in body weight were found.
5) The increase of submaxillary gland weight which followed amputations of lower incisors did not occur in rats treated with pentobarbital, chlorpromazine for 2 days and reserpine for 10 days, but the response of the submaxillary gland to amputatin of lower incisors was increased by the treatment of reserpine and morphine for 2 days.
6) Dibennamine, an alpha-adrenergic blocking agent, not only blocked the response. to amputation of lower teeth but resulted in atrophy of. the submaxillary glands in treated rats.
Inderal, a beta- adrergic blocking agent, blocked the response itself to amputation of lower incisors, but the treatment with atropine, a cholinergic blocking agent, for 2 days blocked partially the effect of amputation. However, the treatment with atropine for 10 days increased the sensitivity of response of submaxillary gland to amputation of lower incisors.
7) Hypertrophy by periodic amputation of lower incisors was abolished by adrenergicblocking agents, chlorpromazine or pentobarbital.
8) The submaxillary gland weight in intact rats was slightly increased by the treatment. with chymotrypsin for 2 days but decreased by the treatment with chymotrypsin for 10-days.
9) The ingestion of ginseng extract to intact rats for 10 days caused the enlargement of the submaxillary gland.
The submaxillary gland weight and total body weight in intact rats were decreased profoundly by exposure to cold enviroment for 10 days, but this decrease was protected by ingestion of ginseng extract for 10 days.
10) Amputation of lower incisors and amputation of lower incisors with dibennamine or inderal administration showed moderate and diffuse stainability to P.A.S. reaction in acinar cells of submaxillary gland, and amputation of lower incisors with atropine administration showed intense stainability to P.A.S. reaction in acinar cells of submaxillary gland.
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