Abstract
Abstract: :
Purpose: As neurogenic inflammation in the ocular surface is acquiring growing relevance, it is becoming essential to complete our knowledge on ocular surface innervation. Alpha–2 adrenergic receptor subtypes have not been described yet in human conjunctiva and this work intends to demonstrate their presence. Methods: The presence of neurotransmitter receptors was analyzed in human normal conjunctiva biopsies using polyclonal antibodies against α2 –adrenergic receptor subtypes (α2A–, α2B–, and α2C–). Negative (omission of primary antibody) and positive (rat kidney, aorta and brain) controls were performed for each antibody. Two techniques were employed: 1) immunofluorescence, using confocal microscopy (n=4) and 2) SDS–polyacrilamide electrophoresis (SDS–PAGE) and Western blotting (n=11). Results: Confocal microscopy studies revealed positive immunoreactivity for α2A– and α2B–adrenergic receptor subtypes in normal human conjunctiva cryosections. No positive reaction was detected for α2C. Western blot analysis of normal human conjunctival homogenates subjected to SDS–PAGE revealed the presence of immunoreactive bands for α2A–, α2B– and α2C–adrenergic receptor subtypes. Conclusion: This study has demostrated the presence of α2A–, α2B–, and α2C–adrenergic receptor subtypes in normal human conjunctiva biopsies. Further functional studies need to prove their degree of functionality in normal and pathological conditions, as well as under pharmacological influence, i.e. the topical application α2–agonists antiglaucoma drugs. Additionally, their implication and putative modulation in neurogenic inflammation deserve further research.
Keywords: conjunctiva • neurotransmitters/neurotransmitter systems • innervation: neural regulation