Effect of autonomic agents on the secretion of N-acetyl-beta-glucosaminidase of mouse submaxillary gland

Protection by selenium of lead-acetate-induced alterations on rat submandibular gland function

Pure submandibular saliva was collected intraorally by micro polyethylene cannulation of anaesthetized rats using pilocarpine as a secretagogue. Twenty-four days treatment with lead acetate 0.05% in drinking water altered salivary function. Except for flow rate that was (P<0.01) increased by lead acetate, the reminder of parameters, concentrations of total protein and calcium and the activity of N-acetyl-beta-D-glucosaminidase (NAG) in submandibular secretions were decreased significantly (P<0.01) by lead acetate. Selenium (2.5 mg l(-1)) in drinking water for 24 days did not induce any significant change in saliva secretory function. Pretreatment by selenium, prevented the lead acetate-induced decrease of NAG activity and concentrations of calcium and protein (P<0.01). The increased flow rate by lead acetate was also affected by selenium pretreatment and reached the level of control. It is concluded that selenium can protect rat submandibular gland function from lead-acetate-induced adverse effects. Properties of selenium as an antioxidant, free radical scavenger and maintenance of cell membrane integrity may be possible mechanisms of its protective effects.

Alteration of rat submandibulary gland secretion of protein, calcium and N-acetyl-beta-D-glucosaminidase activity by lead

1. Effects of various doses of long-term lead treatment (0.01%, 0.04% and 0.05%) on rat submandibular saliva were investigated in this study. 2. Both submandibular ducts were cannulated intraorally with polyethylene tubes and saliva was collected from anesthetized lead treated and control rats using pilocarpine as secretagogue. 3. Saliva protein concentration was found to be reduced in lead (0.04%)- and (0.05%)-treated groups. 4. Saliva calcium concentration had a significant reduction only in the lead (0.05%)-treated group. 5. The secretion of the lysosomal enzyme, N-acetyl-beta-D-glucosaminidase (NAG) in saliva decreased significantly in the lead (0.04%)- and (0.05)-treated groups. Specific activity of the enzyme showed an increase in these treated groups. 6. Good correlations were found between saliva protein concentration and NAG activity, saliva protein and calcium concentrations and calcium concentration and NAG activity. 7. There was a correlation between blood and submandibular saliva lead levels, and the saliva/blood ratio was approximately constant for all treated groups. 8. With respect to the ability of lead to substitute for calcium in several intracellular regulatory events, explanation for these alterations in submandibular saliva composition can be made.

Inhibition by lithium of gentamicin-induced release of N-acetyl-beta-D-glucosaminidase in rat submandibular saliva

1. The effects of gentamicin, lithium and concurrent treatment of these drugs on concentration of total protein and activity of the enzyme N-acetyl-beta-D-glucosaminidase (NAG) in rat submandibular saliva were studied. 2. Pure submandibular saliva was collected intraorally by micropolyethylene canula from anesthetized rats with the use of pilocarpine as secretagogue. 3. Daily intraperitoneal injection of gentamicin (50 mg kg/day) for 5 consecutive days caused a marked increase in total protein concentration and the NAG activity. 4. Chronic treatment of rats for 10 days with lithium chloride solution (1,200 mg/l) caused a significant decrease in total protein concentration but did not affect the NAG activity. 5. Concurrent treatment of lithium with gentamicin caused the total protein concentration and the NAG activity of submandibular saliva to reach to those of controls. 6. In this regard, the protective effects of lithium may be due to interference of this ion with the phosphoinositide cycle.

Effects of gentamicin on rat submandibulary gland functions

1. Submandibular saliva was collected from anesthetized gentamicin-treated and control rats using carbachol, isoproterenol and pilocarpine as secretagogue. 2. Intraperitoneal injection of a large single dose (80 mg/kg) of gentamicin caused marked changes in saliva flow rate, protein and electrolyte concentrations in the presence of parasympathetic or sympathetic agents used as stimulants. 3. The secretion of N-acetyl-beta-D-glucosaminidase in saliva was determined and there was a marked increase in the enzyme activity of saliva of gentamicin-treated rats in comparison to that of controls. 4. The results of this study suggest that gentamicin as an aminoglycoside antibiotic at the dose employed, can influence the secretory mechanisms of rat submandibular glands.