Ectopic sympathetic preganglionic neurons maintain proper connectivity in the reeler mutant mouse

Abstract

The location of sympathetic preganglionic neurons (SPN) in the spinal cord of the reeler mouse mutant is abnormal. Instead of their normal location in the intermediolateral column, the majority of SPN in the reeler cluster around the central canal. To determine whether ectopically located SPN in the reeler form appropriate synaptic connections with their pre- and postsynaptic partners, we examined 1) whether the axons of descending neural pathways that normally terminate on SPN follow them to their ectopic location, and 2) whether the central autonomic neural circuit that controls sympathetic output to the kidney is organized normally in the reeler. Using antibodies against tyrosine hydroxylase, serotonin, neuropeptide Y, substance P and calcitonin gene-related peptide as markers for adrenergic, serotonergic and peptidergic terminals, we found that axons which normally innervate SPN follow these neurons to their ectopic spinal location in the reeler. Injection of pseudorabies virus into the kidney of wild type and reeler mutant mice revealed similar patterns of renal sympathetic and pre-sympathetic control circuits in the spinal cord, brainstem and forebrain. These results indicate that the presynaptic inputs and postsynaptic targets of SPN in the reeler are normal, despite the ectopic spinal location of their cell bodies.