Can L-Methionine and S-Adenosyl-L-Methionine Effectively Mitigate Scopolamine-Induced Cognitive and Motor Deficits in Mice?

Motor balance deficits often coincide with cognitive deficits in older adults. Current medications provide temporary relief with several potential side effects. Essential amino acids and their derivatives, such as S-Adenosyl-L-Methionine (SAMe), can improve nerve function, mood regulation, and neuroprotection against neurodegenerative diseases. This study investigated the protective effects of SAMe in scopolamine-degraded memory, and motor balance in an animal model.

To evaluate the possible effects of SAMe on cognitive and motor balance improvement, both Shuttle box and rotarod methods were performed in seven groups of animals (n=7). The mice groups received the saline (control), scopolamine, scopolamine+rivastigmine, scopolamine +methionine, and scopolamine+ three different doses of SAMe daily and separately for two weeks. Data were analyzed independently by one-way ANOVA and P<0.05 was considered significant.

SAMe 150 mg/kg worsened scopolamine-induced memory impairment (P<0.001), while methionine (100 mg/kg) or SAMe (only 100 mg/kg) together with scopolamine could reduce the duration of the animal's presence in the dark chamber (P<0.05). Daily administration of methionine and SAMe at the rate of 100 mg/kg daily could significantly improve the decrease in motor balance caused by scopolamine (P<0.05). Rivastigmine improved memory and motor balance impairment caused by scopolamine (P<0.05). No difference between SAMe and L-methionine for memory, and balance.

The results suggest that while L-methionine and SAMe may not be effective in improving memory impairments (Even SAMe high doses can aggravate the destruction of passive avoidance memory), they may be beneficial in enhancing motor balance.