Fatemeh Khakpai - Cognitive and Neuroscience Research Center (CNRC), Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran

Parkinson’s disease (PD) is a common neurodegenerative disease resulting from the degeneration of dopaminergic (DA) neurons in the striatum. Anxiety is prevalent nonmotor manifestations of PD. Some studies have suggested a relationship between anxiety and signal molecules such as nitric oxide (NO) in PD. In this study, the nature of the relationship between anxiety symptoms and signal molecules (NO) and PD described. Adult male mice (∼25–30 g), were anesthetized using ketamine hydrochloride (50 mg/kg) plus xylazine (5 mg/kg). The animals were unilaterally implanted with the cannula in the striatum (A=0.4 mm, L=−1.8 mm, V=−3.5). Then, they received unilateral stereotaxic injections of 1 microlitre of 4μg/l of 6-hydroxydopamine hydrobromide (6-OHDA, Sigma) dissolved in physiological saline containing 0.01%ascorbic acid. Infusions were delivered over 1 min via a 30 gauge stainless steel cannula. 3 weeks after administration of 6-OHDA, DA neurons were destroyed and PD was induced. A standard elevated plus-maze was used to determine anxiety levels in animals. Intra-parietal injection of different doses of L-arginine (L-arg), an NO precursor (3, 6 and 9 mg/kg) increased %OAT [P<0.01], %OAE (P<0.01) and locomotor activity (P < 0.001), suggesting an anxiolytic-like behavior. While, NG-nitro-L-argmethylester(L-NAME), a potent inhibitor of NO-synthase (NOS; 3, 6 and 9 mg/kg) decreased %OAT (P<0.05) and locomotor activity (P<0.001) (indicating an anxiogeniclike behavior) but not %OAE in mice model of PD. The results indicate a modulatory role for NO in the anxiety response in mice model of PD. Further studies investigating the temporal dynamics of anxiety and PD are needed.

PD, L-arginine, L-NAME, Anxiety