Effects of physostigmine on local cerebral glucose utilization in the central components of the rat visual system

The effects of intravenous administration of physostigmine at doses of 0.03, 0.095, or 0.3 mg/kg on local cerebral glucose utilization (LCGU) were determined in 3 structures of the visual system of the rat brain by means of the quantitative 2-[14C]deoxyglucose method. LCGU was increased in the superior colliculus (superficial gray layer), but unchanged in the visual cortex and the lateral geniculate body. To determine whether the observed effect of physostigmine on the superior colliculus depended on input from the retina, the highest dose of physostigmine was administered to rats which had previously been enucleated bilaterally. Enucleation decreased LCGU in the superior colliculus of the animals not treated with physostigmine and blocked the effect of physostigmine on LCGU. The effect of physostigmine in the superior colliculus appears, therefore, to depend on input from the retina.