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Updated: May 18, 2026

In Vitro Method to Study Sex-Based Differences in Conjunctival Goblet Cells
Published on: July 28, 2023
Effect of histamine on Ca(2+)-dependent signaling pathways in rat conjunctival goblet cells
Dayu Li1, Richard B Carozza, Marie A Shatos
1Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
Purpose:
The purpose of this study was to determine the Ca(2+)-dependent cellular signaling pathways used by histamine to stimulate conjunctival goblet cell secretion.
Methods:
Cultured rat goblet cells were grown in RPMI 1640. Goblet cell secretion of high molecular weight glycoconjugates was measured by an enzyme-linked lectin assay. Intracellular [Ca(2+)] ([Ca(2+)](i)) was measured by loading cultured cells with the Ca(2+) sensitive dye fura-2. The level of [Ca(2+)](i) was measured using fluorescence microscopy. Extracellular regulated kinase (ERK) 2 was depleted using small interfering RNA (siRNA).
Results:
Histamine-stimulated conjunctival goblet cell secretion of high molecular weight glycoproteins was blocked by removal of extracellular Ca(2+) and depletion of ERK2 by siRNA. Histamine increase in [Ca(2+)](i) was desensitized by repeated addition of agonist and blocked by a phospholipase C antagonist. Histamine at higher doses increased [Ca(2+)](i) by stimulating influx of extracellular Ca(2+), but at a lower dose released Ca(2+) from intracellular stores. Activation of each histamine receptor subtype (H(1)-H(4)) increased [Ca(2+)](i) and histamine stimulation was blocked by antagonists of each receptor subtype. The H(2) receptor subtype increase in [Ca(2+)](i) was cAMP dependent.
Conclusions:
We conclude that histamine activates phospholipase C to release intracellular Ca(2+) that induces the influx of extracellular Ca(2+) and activates ERK1/2 to stimulate conjunctival goblet cell mucous secretion, and that activation of all four histamine receptor subtypes can increase [Ca(2+)](i).
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