An epithelial debridement wound, as a stimulus to the cornea, causes conjunctival goblet cell mucous secretion in that eye. To determine if this stimulation of secretion is neurally mediated, rats were anesthetized and the local anesthetic lidocaine (1%) or buffer alone was administered topically and/or subconjunctivally for 15 min. A corneal epithelial debridement wound was made in one eye. The contralateral eye served as the control. After 5-120 min, animals were sacrificed and inferior bulbar conjunctival buttons removed. Mucus in the goblet cells was stained with Alcian blue and periodic acid-Schiff's reagent to indicate mucin-containing goblet cells. The number of mucin-containing goblet cells/0.16 mm2 was determined by light microscopy; a decrease in number indicated an increase in mucous secretion. Stimulation by corneal wounding induced goblet cell mucous secretion in that eye. Secretion was observed as rapidly as 5 min after stimulus and for as long as 120 min. Topical application of lidocaine, subconjunctival injection of lidocaine, or a combination of both inhibited wound-induced stimulation of mucous secretion. We conclude that conjunctival goblet cell mucous secretion can be neurally mediated and could serve as an immediate response to protect the ocular surface.

Neural stimulation of the cornea induces conjunctival goblet cell mucous secretion. Immunofluorescence microscopy was used to determine if nerves are present near conjunctival goblet cells and what types of nerves are present. In euthanized rats, the local anesthetic lidocaine (1%) was placed topically on the ocular surface for 10 min to prevent goblet cell mucous secretion. The ocular surface tissues were removed and either fixed in formaldehyde and then frozen, or frozen first and then post-fixed in formaldehyde. Tissue was sectioned and nerves localized by indirect immunofluorescence microscopy, using antibodies to synaptophysin (indicates nerve, independent of type), vasoactive intestinal peptide (VIP, indicates parasympathetic nerves), tyrosine hydroxylase (TH, indicates sympathetic nerves), dopamine beta-hydroxylase (DBH, indicates sympathetic nerves), phenylethanolamine-N-methyltransferase (PNMT, indicates sympathetic nerves), and calcitonin gene-related peptide (CGRP, indicates sensory nerves). Goblet cells were identified by phase-contrast microscopy. Synpatophysin-containing nerves were present in the basolateral region of conjunctival goblet cells clusters. Nerve fibers immunoreactive to VIP were found in the conjunctiva along the epithelial-stromal junction and around the basolateral aspect of goblet cell clusters. Nerve fibers immunoreactive to TH and DBH were detected surrounding goblet cells and in the conjunctival stroma. Nerve fibers immunoreactive to CGRP were detected in the epithelium and at the epithelial stromal junction, but were not localized near goblet cell clusters. CGRP-containing nerve fibers were also detected in the conjunctival stroma under the epithelium. We conclude that efferent parasympathetic and sympathetic, but not afferent sensory, nerves appear to be located adjacent to conjunctival goblet cell clusters. Activation of efferent parasympathetic and sympathetic nerves could directly stimulate conjunctival goblet cell mucous secretion. Antidromic activation of afferent sensory nerves releasing neurotransmitters could stimulate goblet cell secretion by a paracrine mechanism.