Possible role of the submandibular gland in the development of obesity in mice.

The possible role of submandibular glands (SMG) in the development of obesity was studied in two types of genetically obese mice, ob/ob and yellow Ay: Obesity is caused by hyperplasia followed by hypertrophy in ob/ob mice and mainly by hypertrophy in Ay mice. The histological features of SMGs exhibited clear sexual dimorphism in both mice similar to lean controls. The SMGs of ob/ob mice was smaller in size and had smaller granular convoluted tubular portions than lean controls, while the SMGs of Ay mice did not differ from lean controls. Sialoadenectomy before and after development of obesity generally reduced the gain of body weights in both sexes of Ay mice but not in ob/ob mice. The content of epidermal growth factor (EGF) in the SMGs was higher in Ay mice and lower in ob/ob mice than their controls. The possible role of EGF in the SMGs in the development of obesity is discussed.