Amphetamine Sensitization Alters Dendritic Morphology in Prefrontal Cortical Pyramidal Neurons in the Non-Human Primate

Amphetamine (AMPH) sensitization in the nonhuman primate induces persistent aberrant behaviors reminiscent of the hallmark symptoms of schizophrenia, including hallucinatory-like behaviors, psychomotor depression, and profound cognitive impairment. The present study examined whether AMPH sensitization induces similarly long-lasting morphologic alterations in prefrontal cortical pyramidal neurons. Three to 3½ years postsensitization, sensitized, and AMPH-naïve control monkeys were killed. Blocks of prefrontal cortex were Golgi-impregnated for elucidation of pyramidal dendritic morphology in layers II/superficial III (II/IIIs), deep III, and V/VI. In AMPH-sensitized animals as compared to AMPH-naïve controls, pyramidal dendrites in layer II/IIIs exhibited reduced overall dendritic branching and reduced peak spine density (22%) on the apical trunk. Across all layers, the distance from soma to peak spine density along the apical trunk was decreased (126.38±7.65 μm in AMPH-sensitized compared to 162.98±7.26 μm in AMPH-naïve controls), and basilar dendritic length was reduced (32%). These findings indicate that chronic dopamine dysregulation, consequent to AMPH sensitization, results in enduring, atrophic changes in prefrontal pyramidal dendrites that resemble the pathologic alterations described in patients with schizophrenia and may contribute to the persistence of schizophrenia-like behavioral changes and cognitive dysfunction associated with sensitization. These findings may also provide key insights into the etiologic origin of the pronounced behavioral disturbances and cognitive dysfunction associated with schizophrenia.