Cellular physiological studies in the mechanisms of salivation with ageing

1994 Fiscal Year Final Research Report Summary

• Project/Area Number: 05671550
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Functional basic dentistry
• Research Institution: Meikai University
• Principal Investigator: UEHA Takao Meikai University, School of Dentistry, Professor, 歯学部, 教授 (20049365)
• Co-Investigator(Kenkyū-buntansha): SUGITA Kenji Meikai University, School of Dentistry, Assistant, 歯学部, 助手 (90171157) ; KURIHARA Kinji Meikai University, School of Dentistry, Assistant, 歯学部, 助手 (10170086)
• Project Period (FY): 1993 – 1994
• Keywords: Parotid gland / Submandibular gland / Rat / Ageing / Na^+, K^+-ATPase / Autonomic transmitter receptors / Salivary flow / Blood flow

Research Abstract

It is well known that deterioration in physiological functions in the body occurs with ageing. Decline in salivation is also suggested in the field of dentistry. We think that it is important to clear up the mechanisms of these phenomena in order to prevent lowering major oral functions like mastication or conversation. So we compared receptor functions, stimulated secretion, and blood flow in salivary glands among aged (50-60 weeks old), mature (10-12 weeks old), and young (2weeks old) rats.
Na^+, K^+-ATPase activities in submandibular and parotid glands in young rats were low in comparison with mature animals. No obvious changes were seen in Na^+, K^+-ATPase activities in submandibular glands, but lowering of its activity was observed in parotid glands in aged rats. No changes of localization of this enzyme was seen ; located on ducts in both glands of every animals by means of immunochistohemical staining. Affinity in receptor binding to neurotransmitters or cytosolic calcium mobilization was not changed by ageing.
Lowering or delay of responses to the stimulation was not observed in salivary flow or blood flow, but decline in the ability to maintain salivation and blood flow in submandibular glands of aged rats in compared with mature animals. No increase in salivation or blood flow was observed in young rats. Though it is complete in receptor functions, it is thought that the growth in salivary glands is insufficient in young animals.
We conclude that fibrosis in the gland and decline in sustaining ability for salivation occur without changes in characters of Na^+, K^+-ATPase or of proteins consisting receptors for autonomic transmitters.