Abstract
Purpose: :
Alpha 2 adrenergic receptors are regulatory receptors and their stimulation decreases adrenergic activity. This study was done to determine the physiological function of the alpha 2 receptors in the retina.
Methods: :
Retinal sections were prepared from eyes that were dark adapted 16 hours or those that were exposed to light for 4 to 6 in the regular 12 hour light/dark cycle. These sections were immunostained with antibodies against alpha 2A, 2B or 2C to identify their location in the two conditions.
Results: :
In retinas that were exposed to light for 4 to 6 hours 2A receptors were localized in the ganglion cell layer and the inner most cells in the inner nuclear layer. Alpha 2B receptors were found in most cells throughout the retina and alpha 2C were localized in the photoreceptor soma and inner segments. Following dark adaptation for 16 hours, there was little change in the distribution of alpha 2A receptors. Alpha 2 B receptors were mainly located in the inner plexiform layer and the staining was more intense than the light adapted ones. In dark adapted retinas the location of alpha 2C was in the photoreceptor soma only and very little was seen in the inner segment. The intensity was much weaker in the dark adapted retinas compared to the light adapted ones.
Conclusions: :
This study suggests that alpha 2 adrenergic receptor activation may have some input in retinal light dark adaptation.
Keywords: neurotransmitters/neurotransmitter systems • pharmacology • retina: neurochemistry