Effect of Sympathetic Innervation on Isoproterenol-Induced Cystatin S Gene Expression in Rat Submandibular Glands during Early Development

Abstract

The rat submandibular gland is innervated by both sympathetic and parasympathetic branches of the autonomic nervous system which, in turn, regulate the secretory function of the gland. Parasympathetic innervation of rat submandibular glands is present at birth; in contrast, sympathetic innervation reaches the glands by postnatal day 5. Isoproterenol (IPR), a β-adrenoreceptor agonist, induces hypertrophic and hyperplastic enlargement of rat salivary glands, and induces the expression of a number of genes, including cystatin S (Cys S), a member of family 2 of the cysteine proteinase inhibitor superfamily. Cys S gene expression is tissue specific, cell type specific, occurs temporally during normal development and is not observed in adult animals unless stimulated by IPR. In addition, sympathectomy of adult rat submandibular glands reduced IPR-induced expression of the Cys S gene. This paper reports experiments analyzing the participation of the sympathetic branch of the autonomic nervous system in IPR-induced expression of the cystatin S gene during early development of the submandibular gland. The rat Cys S gene could be induced by IPR by day 3, and the level of Cys S mRNA remained constant until 8 days at which time a dramatic IPR induction of Cys S mRNA was observed. This statistically significant increase in Cys S mRNA at 8 days was diminished, but not completely suppressed, upon sympathectomy of 1-day-old animals. These data indicate that an intact sympathetic innervation is not a requisite for IPR-induced Cys S gene expression in developing submandibular glands; however, sympathetic innervation is required for the full IPR response of the Cys S gene in developing submandibular glands. The developmental experiments presented in this paper indicate that factor(s) coming from the sympathetic nervous system participate in IPR-induced expression of the Cys S gene in rat submandibular glands.

Restoration of cardiac transient outward potassium current by norepinephrine in diabetic rats

“…I to maturates at between 10 and 20 weeks of canine postnatal development [10,22], the period when the sympathetic nervous system also maturates [33]. In the rat, both sympathetic innervation of the heart and I to maturate at between 5 and 15 days of postnatal development, and sympathetic stimulation is necessary for I to development [3,13].…”

Cystatin S: Molecular biology and sympathetic innervation

“…4). Morphological analyses of developing rat SMG show a continuous change in the composition of acinar and proacinar cell populations at 3,5, and 8 days of age (100). The levels of cystatin mRNA in the SMG of IPRtreated rats do not parallel the changes in acinar and proacinar cell populations, and are not significantly different between 3 and 6 days of age, indicatingthat IPR-induced expression ofthe rat cystatin S gene during early development ofthe SMG is not j ust a function ofthe degree of differentiation ofthe acinar cells.…”