Effects of cypermethrin exposure on learning and memory functions and anxiety-like behavior in rats

Cypermethrin (CYP), a synthetic pyrethroid widely used to control plant pests, has been associated with various diseases in humans exposed to pesticides, either directly or indirectly. This study aimed to examine the effects of CYP on learning and memory functions, as well as anxiety-like behavior.

Forty male Wistar rats (8 weeks old) were randomly assigned to 4 groups: The first group served as the control, while the other three groups received different doses of CYP (5, 20, and 80 mg/kg) via gavage once daily for one month. Passive avoidance learning (PAL) and memory were assessed using the shuttle box test, cognitive memory was evaluated using the novel object recognition (NOR) test, and spatial memory was measured with the Morris water maze (MWM) test. The elevated plus-maze (EPM) and open field tests were used to assess locomotor activity and anxiety levels.

In the PAL test, significant differences were observed in the time spent in the dark compartment (TDC) and step-through latency in the retention trial (STLr) in rats receiving 80 mg/kg of CYP. MWM results indicated memory impairment in rats treated with 20 and 80 mg/kg of CYP. Additionally, rats treated with the highest dose of CYP (80 mg/kg) showed a reduction in the number of entries into the open arms of the EPM compared to the control group.

This study demonstrates that CYP negatively affects learning and memory retention. Further research is needed to explore the precise mechanisms by which this toxin impacts cognitive functions.