<p>The inactivation of the cerebral transmembrane Na⁺/K⁺-ATPase has been reported in Parkinson’s disease (PD), although the cause or effect debate is yet to be fully clarified. In the present study, we sought to further explore this using rotenone models of PD, while harnessing the toxicokinetic dynamics attributed to different routes of rotenone administration to investigate the correlation between disease phenotype severity and oxidative stress-mediated enzyme inactivation. In comparing the effect of different routes of rotenone administration, male Wistar albino rats (200–250&#xa0;g) were randomly grouped into four (four animals in each group) namely: control, oral, intraperitoneal (IP), and subcutaneous (SC). The animals were administered rotenone (50&#xa0;mg/kg p.o.) via oral, intraperitoneal (3&#xa0;mg/kg i.p.) and subcutaneous (3&#xa0;mg/kg s.c.) routes, respectively, with the control group receiving the vehicle (2% DMSO ⁺ 98% normal saline (0.85%)). Rotenone administration was terminated when PD phenotypes became debilitating (7 days from start of rotenone administration), and the effect of treatment was evaluated by the evaluation of motor function and weight of animals. Biochemical evaluation of oxidative stress was carried out on five different brain regions (the cortex, cerebellum, midbrain, striatum, and hippocampus) for total and non-protein thiol levels, lipid peroxidation, and Na⁺/K⁺-ATPase activity. The results showed region-specific loss of enzyme activity and oxidative stress that varied with different routes of administration, with the intraperitoneal route showing the most deleterious effect. It is clear from the results that the severity of PD phenotypes is positively correlated to oxidative damage and Na⁺/K⁺-ATPase inactivation.</p>