Structural neuroplasticity induced by melatonin in entorhinal neurons of rats exposed to toluene inhalation.

Several clinical studies have shown that abusing volatile solvents, mainly toluene, produces neurological, neuropathological and neuropsychiatric disorders. Symptoms of these disorders include loss in impulse control, distractibility and memory deficits, which are associated with mild brain atrophy. The entorhinal cortex is critically involved in mnemonic processes, and memory disorders are the major symptom detected in chronic solvent abusers. Therefore, in the present study, we evaluated (1) whether the entorhinal neuronal morphology was impaired by subchronic toluene exposure and (2) if melatonin protected the neuronal cytoarchitecture, as has been demonstrated in neocortical neurons. Consistent with our previous findings, the present study indicates that the entorhinal cell dendritic arborization was significantly reduced in toluene exposed animals, and melatonin administration significantly rescued the reduced dendritic branching induced by toluene neurotoxicity.