The alpha1- and beta1-adrenergic modulation of lacrimal gland function in the mouse.

PURPOSE

To determine the expression patterns of alpha(1)- and beta(1)-adrenergic receptors in the mouse exorbital lacrimal gland (LG). An alpha- and beta-receptor agonist and antagonist were used to elucidate the receptors' relevance to protein secretion.

METHODS

Mouse LGs were processed for single- and double-labeled indirect immunofluorescence studies and examined with confocal scanning microscopy. Protein secretion was measured from gland fragments in response to adrenergic agonists.

RESULTS

Extensive alpha(1)-immunoreactivity (IR) was found on the surface and cytoplasm of acinar cells and much more alpha(1)-IR in the interstitial areas. In contrast, more beta(1)-IR was found in the LG, and most beta(1)-IR appeared to concentrate in the cytoplasm of acinar cells, with almost no beta(1)-IR in the interstitial areas. The protein secretion in response to phenylephrine and isoproterenol showed that direct stimulation of either the alpha(1)- or beta(1)-receptor could induce significant protein secretion from LGs. The specificity of this stimulation was further indicated by the effects of adrenergic antagonists. No synergism was observed between alpha(1)- and beta-receptor-mediated protein secretions.

CONCLUSIONS

The results support the notion that there is extensive adrenergic control in the mouse LG. The adrenergic receptors may be a better choice of markers, compared with tyrosine hydroxylase and dopamine beta-hydroxylase, to reflect the extent of adrenergic control because circulating norepinephrine in the bloodstream should be taken into consideration. Both confocal microscopy observations and protein secretion data suggest the presence of alpha(1)- and beta(1)-mediated pathways in the mouse LG.