Peroxidase secretion by lacrimal glands from juvenile F344 rats.

Secretion of peroxidase by rat lacrimal glands is generally acknowledged to be greater in juvenile rats than in adults. However, this phenomenon has not been so well documented in lacrimal glands as other age-related changes have been. Therefore, we studied lacrimal protein and peroxidase secretion in response to muscarinic cholinergic and alpha-adrenergic stimulation of glands from 35- to 90-day-old male F344 rats. Lacrimal tissue fragments were incubated in perifusion chambers, and secretion of protein and peroxidase was measured in response to stimulation by carbachol or phenylephrine. There was a negative first-order correlation between total protein secretion and age. Dose-response curves showed that at the highest doses there was a small but significant change in protein secretion. Secretion of lacrimal peroxidase in response to carbachol and phenylephrine changed significantly with increasing age. The tissue content of peroxidase was diminished by about 25% during this period, but that decrease alone was not sufficient to explain the changes in secretory responsiveness. The decrease of peroxidase secretion elicited by phenylephrine had both first- and second-order components in its correlation with age between 35 and 90 days. Dose-response curves for 5-week (35-41-day)- and 12-week (84-90-day)-old tissue showed that the maximum secretion of peroxidase was reduced by about 50%, but with no apparent shift in the dose-response curve.(ABSTRACT TRUNCATED AT 250 WORDS)