A neuroanatomical analysis of the effects of a memory impairing dose of scopolamine in the rat brain using cytochrome c oxidase as principle marker

•The effects of SCP are not ultimately restricted to cognitive parameters.•Administration of SCP reduced ChAT expression levels in the CA1 and amygdala.•Injection of SCP reduced the number of c-Fos cells in the amygdala only.•COX expression was reduced in the movement, memory and anxiety-related structures.•Our findings suggest an anxiety and locomotor-related behavioral effects of SCP.

Acetylcholine plays a role in mnemonic and attentional processes, but also in locomotor and anxiety-related behavior. Receptor blockage by scopolamine can therefore induce cognitive as well as motor deficits and increase anxiety levels. Here we show that scopolamine, at a dose that has previously been found to affect learning and memory performance (0.1 mg/kg i.p.), has a widespread effect on cytochrome c oxidase histochemistry in various regions of the rat brain. We found a down-regulation of cytochrome c oxidase in the nucleus basalis, in movement-related structures such as the primary motor cortex and the globus pallidus, memory-related structures such as the CA1 subfield of the hippocampus and perirhinal cortex and in anxiety-related structures like the amygdala, which also plays a role in memory. However choline acetyltransferase levels were only affected in the CA1 subfield of the hippocampus and both, choline acetyltransferase and c-Fos expression levels were decreased in the amygdala. These findings corroborate strong cognitive behavioral effects of this drug, but also suggest possible anxiety- and locomotor-related changes in subjects. Moreover, they present histochemical evidence that the effects of scopolamine are not ultimately restricted to cognitive parameters.