ABSTRACT
Tearing maturates rapidly after birth, and external environmental challenges play a key role in promoting lacrimal functional maturation. However, little is known about the facilitative factors underlying this developmental process or the potential of application of these factors to treat hypofunction of the lacrimal gland. In this study, eye opening and the subsequent ocular surface sensory experience, which is thought to be involved in postnatal maturation of lacrimal function, were investigated. Our results demonstrated that eye opening after birth is essential for the maturation of neonatal tearing. The maturation process of lacrimal function is dependent on the ocular surface sensory experience via transient receptor potential cation channel subfamily member 1 after birth. This study provides, for the first time, important evidence of the sensory experience of the ocular surface in relation to the maturation of functional tear secretion during the postnatal period.
Subject(s)
Cornea/physiopathology , Lacrimal Apparatus Diseases/etiology , Rupture/etiology , TRPV Cation Channels/physiology , Animals , Animals, Newborn , Lacrimal Apparatus Diseases/metabolism , Lacrimal Apparatus Diseases/pathology , Mice, Inbred C57BL , Mice, Knockout , Rupture/metabolism , Rupture/pathologyABSTRACT
Intracellular calcium ([Ca2+]i) signaling regulates physiological functions in most cells. In secretory organs, such as the pancreas, salivary gland, and lacrimal gland (LG), [Ca2+]i elevation in acinar cells triggers fluid secretion, which plays vital roles in the maintenance of functional health across the life-course. It is important to understand the secretory mechanism of secretory organs, but lack of analytic systems available for living animals limits the scope of research to gain deeper insights into the precise mechanism of secretion. We established an intravital imaging system for specific cell types of secretory organs to monitor the [Ca2+]i changes using mouse line expressing Yellow Cameleon 3.60, a genetically encoded Ca2+ indicator. Elevation of [Ca2+]i in specific cell types of secretory organs could be monitored after cholinergic stimulation ex vivo and intravitally. We found that a marked attenuation of LG [Ca2+]i response to cholinergic stimulation was induced under pathological conditions by postganglionic denervation. Intravital Ca2+ imaging in secretory organs will broaden our understanding of the cellular mechanisms in animal models of secretory diseases.
Subject(s)
Calcium Signaling , Calcium-Binding Proteins/metabolism , Lacrimal Apparatus/metabolism , Pancreas/metabolism , Salivary Glands/metabolism , Acinar Cells/metabolism , Animals , Calcium-Binding Proteins/genetics , Fluorescence Resonance Energy Transfer , Mice , Mice, Transgenic , Optical ImagingABSTRACT
Sea buckthorn (Hippophae rhamnoides)-derived products have traditionally been used as food and medicinal ingredients in Eastern countries. The purpose of this study was to investigate the effect of oral intake of sea buckthorn oil products on tear secretion using a murine dry eye model. Orally administered sea buckthorn pulp oil (not seed oil) restored aqueous tear secretion to its normal value under a dry eye condition. Palmitoleate (C16:1), a fatty acid present in sea buckthorn pulp oil, preserved tear secretion and suppressed inflammatory cytokines in the lacrimal gland to the same extent as that by pulp oil. These results suggest that an oral intake of sea buckthorn pulp oil has a potency to preserve tear secretion capacity in the dry eye state and palmitoleate, its main constituent fatty acid, is an active component of the oil. This effect may enable a potent diet-based treatment for the prevention of dry eye.
