Cellular, Behavioral, and Locomotor Effects of Oral Nicotine in Male Rats with Bilateral Lesions in the Ventrolateral Striatum Induced with 6-OHDA

Objective: Parkinson's disease is a progressive neurodegenerative disease having a spectrum of non-motor to motor symptoms. Unrelated to motor symptoms of sensory, autonomic, and neuropsychiatric symptoms often appear early in the course of the disease. It is a remarkable observation that patients in the premotor phase can easily quit smoking without help. This study was intended to investigate the interrelation between nicotine and the partial loss of dopaminergic innervation in the ventrolateral striatum induced by 6-OHDA. Methods: We used an experimental premotor parkinsonism model. The oral nicotine preference of rats was investigated with the two-bottle free choice method. The behaviors related to locomotor activity and emotional state were evaluated with a locomotor activity test, elevated plus maze, and forced swimming test. Histopathological evaluation was performed in the striatum by staining techniques using hematoxylin+eosin (H&E) and immunohistochemistry markers (caspase-3, and MAP-2). Results: Bilateral 6-OHDA lesions did not lead to a significant alteration in the total locomotor activity or nicotine preference. Nicotine increased horizontal but decreased vertical movements in addition to increasing anxiolytic but also depressive effects in the OHDA lesion group. The number of apoptotic cells was significantly lower in the lesion group receiving nicotine compared to those not receiving nicotine. Conclusion: Our experimental study points to the role of oral nicotine in male rats with bilateral striatal 6-OHDA lesions in the ventrolateral striatum. Further studies are needed to understand the relationship between loss of dopaminergic innervation in the striatum and nicotine consumption.