Distribution of adrenergic receptor subtypes in the retractor muscles of the upper eyelid

Purpose: To identify adrenergic receptor subtypes and their relative distri bution in the retractor muscles of the upper eyelid, the levator palpebrae superioris, and the Muller muscle. The pattern of distribution of these rec eptors in the Muller muscle was further compared in patients with dysthyroi d eyelid retraction and in normal subjects. Methods: Muller muscle specimens were collected from 19 patients undergoing ptosis correction and from 8 patients undergoing repair of dysthyroid eyel id retraction. Immunohistochemical staining for alpha 1-, alpha 2-, beta 1- , and beta 2- adrenergic receptors was performed using antihuman rabbit pol yclonal antibodies. Results: alpha 2-Adrenergic receptors were the predominant subtype in the M uller muscle, and beta 1-adrenergic receptors were the predominant subtype in the levator muscle. There was no significant difference in the staining pattern between specimens collected from patients with dysthyroid eyelid re traction and those from normal subjects. Conclusions: The interaction between the alpha 2 and beta 1 receptors in th e upper eyelid retractor muscles may be important in the control of the upp er eyelid position and may contribute to the development of dysthyroid eyel id retraction. Specific alpha 2 antagonists could be developed and may be e ffective pharmacologic agents for the treatment of eyelid retraction.