Adenosine A1 and benzodiazepine receptors and glucose metabolism in the visual structures of rats monocularly deprived by enucleation or eyelid suture at a sensitive period.

Purpose: To determine the changes in the adenosine A(1) and benzodiazepine receptor density and in glucose metabolism in the visual centers of the rat brain following monocular enucleation or eyelid suture on postnatal day 10 (PN10).

Methods: Following monocular enucleation or eyelid suture on PN10 rats, the alterations in adenosine A(1) and benzodiazepine receptor density, and in glucose metabolism were evaluated in the superior colliculus (SC), the dorsal lateral geniculate body (DLG), and the visual cortex (VC) by ex vivo autoradiography with [11C]MPDX, [11C]flumazenil and [14C]2-deoxyglucose, respectively.

Results: Enucleation reduced the [11C]MPDX binding in the SC and DLG, and enhanced the [11C]flumazenil binding in the SC. Eyelid suture reduced the [11C]flumazenil binding in the VC at day 20. [14C]2-deoxyglucose uptake was not decreased by enucleation in any region except in the SC and DLG at day 1, but was decreased by eyelid suture in the SC at days 20 and 55 and in the VC at day 55.

Conclusions: The decrease in the presynaptic adenosine A(1) receptors in the SC following enucleation is coupled with an upregulation of postsynaptic benzodiazepine receptors. These neural reactions are completely different from those following eyelid suture. The development of neural architecture for visual functions is not completed at PN10 in rats.