A muscarinic M1 receptor antibody is validated for specificity using Western blotting and immunohistochemistry using CNS from wild type and muscarinic M1 receptor knockout mice.

This antibody is used to visualise the distribution of muscarinic M1 receptors in the human hippocampus.

Muscarinic M1 receptor positive cells were most apparent in the deep polymorphic layer of the dentate gyrus, the pyramidal cell layer of cornu ammonis region 3, the cellular layers of the subiculum, layer II of the presubiculum and layer III and V of the parahippocampal gyrus.

Immunostaining suggested some muscarinic M1 receptors were not localised to the cellular membrane. These receptors may be the muscarinic M1 receptor reserve or internalised receptors being degraded.