[Effects of upper incisor separation on the submandibular and sublingual glands of young rats].

The effects of upper incisor separation, chronic isoproterenol (IPR) treatment and a combination with both treatments on the submandibular and sublingual glands of rats were examined and compared biochemically, immunohistochemically and radioimmunologically during 7 days after treatment. The findings obtained were as follows: 1. Both submandibular and sublingual glands of rats were significantly enlarged by an orthodontic appliance and chronic IPR treatment, and in combination with both treatments they were much more markedly enlarged additively during 7 days of treatment. This enlargement was followed, in general, by a significant increase of both RNA and DNA contents, and the incorporation of BrdU into the glandular cells, especially acinar cells, with some evidence of hyperplasia and hypertrophy. 2. Enlargement of the submandibular glands induced by orthodontic treatment was mediated via superior cervical ganglion, chorda tympani and lingual nerves, whereas of the sublingual glands mainly via chorda tympani and lingual nerves with some evidence of the mutual interactions among these nerves. 3. The secretory functions of the submandibular glands were significantly reduced at early stages after orthodontic treatment in contrast to those of chronic IPR treatment with and without orthodontic treatment. 4. The synthesis of LM protein, mainly localized in the acinar cells, was increased by orthodontic treatment in combination with adrenergic blockers, prazosin, metoprolol and ICI 118551, whereas in chronic IPR treatment it was significantly reduced by metoprolol, but not by prazosin and ICI 118551. LM protein was secreted into saliva at 6 h after IPR treatment.