Presence of nerves and their receptors in mouse and human conjunctival goblet cells

PURPOSE. To determine whether neural pathways for controlling goblet cell s ecretion are present in mouse and human conjunctiva. METHODS. Mouse conjunctiva was homogenized and subjected to electrophoresis and Western blotting to detect PGP 9.5 (indicates nerves), muscarinic rece ptor subtypes (indicates parasympathetic pathway), and adrenergic receptors (indicates sympathetic pathway). Mouse eyes and human conjunctival tissue were analyzed by immunofluorescence microscopy. Antibodies to vasoactive in testinal peptide (VIP), tyrosine hydroxylase (TH), dopamine beta -hydroxyla se (DBH), and muscarinic and alpha (1)- and beta -adrenergic receptor subty pes were used. RESULTS. Western blot demonstrated PGP 9.5, M-1, M-2, and M-3 muscarinic re ceptors and alpha (1A)-, beta (1)-, beta (2)-, and beta (3)-adrenergic rece ptors in mouse conjunctiva. Immunoreactivity for VIP, TH, and DBH was found adjacent to mouse and human goblet cells. M-1 and M-2 muscarinic receptors were identified throughout mouse conjunctiva, but M-3 receptor was predomi nantly on goblet cells. All three muscarinic receptor subtypes were detecte d on goblet cells in human conjunctiva. alpha (1A)-Adrenergic receptors wer e found on epithelial cells and on goblet cells in mouse and human conjunct iva. beta (1)- and beta (2)-Adrenergic receptors were found on both epithel ial and goblet cells in mouse conjunctiva, but not on human conjunctival ce lls. beta (3)-Adrenergic receptors were found on both epithlial and goblet cells in human conjunctiva but not on mouse conjunctival cells. CONCLUSIONS. The following conclusions were drawn: parasympathetic nerves a nd M-1 M-2, and M-3 muscarinic receptors, as well as sympathetic nerves are present on mouse and human goblet cells. The adrenergic receptors beta (1) and beta (2) but not alpha (1A) and beta (3) are present on mouse conjunct ival goblet cells, whereas alpha (1A) and beta (3), but not beta (1) and be ta (2) are present on human conjunctival goblet cells, suggesting that thes e nerves and receptors could activate goblet cell secretion in mouse and hu mans.