ANDROGEN CONTROL OF SECRETORY COMPONENT MESSENGER-RNA LEVELS IN THE RAT LACRIMAL GLAND

The purpose of this investigation was to determine whether the known g ender-related differences in, and the endocrine control of, the produc tion of secretory component (SC) by the rat lacrimal gland are associa ted with alterations in SC mRNA content. Levels of SC mRNA were measur ed in lacrimal tissues of intact, sham-operated, castrated, hypophysec tomized, and testosterone-treated male and female adult rats by Northe rn blot procedures, which utilized a specific, [alpha-P-32]-labelled r at SC cDNA probe. For control purposes, SC mRNA amounts were standardi zed to the beta-actin content in experimental blots. The location of S C mRNA in lacrimal glands was evaluated by in situ hybridization techn iques, which involved exposure of tissue sections to sense or anti-sen se [S-35]-labelled SC RNA probes. Our results demonstrate that: (1) la crimal glands of male rats contain a significantly greater amount of S C mRNA than those of female rats, and that this difference co-exists w ith distinct, gender-associated variations in the distribution of SC m RNA in lacrimal tissue; (2) orchiectomy or hypophysectomy, but not ova riectomy or sham surgery, leads to a marked decline in the lacrimal SC mRNA content; and (3) testosterone, but not placebo, administration t o castrated male and female rats induces a significant increase in the SC mRNA levels in lacrimal tissue. Overall, these findings show that gender, androgens and the hypothalamic-pituitary axis exert a consider able influence on the SC mRNA content in the rat lacrimal gland.