Objective: It is known that chronic stress increases depression-like behaviors. Geraniol is a natural monoterpene known for its neuromodulatory and antidepressant effects. This study was designed to investigate the possible effects of geraniol on the cholinergic system in chronic restraint stress depression model rats.

Materials and Methods: 21 adult female rats were used in the study. Restraint stress was applied to rats for 5 hours a day for 3 weeks. Geraniol was administered at 100 mg/kg by oral gavage. Anxiety was evaluated with the open field test, and depression-like behaviors were evaluated with the forced swimming test following stress and drug administration. Then the rats were euthanized and the hippocampus was dissected. Acetylcholine (ACh) and acetylcholinesterase (AChE) levels were determined in hippocampal tissue homogenates by ELISA method.

Results: Stress exposure did not significantly affect anxiety-like behavior, but it stimulated depression-like behavior parameters in forced swimming tests. It was determined that geraniol significantly decreased the increased immobility time due to stress (p<0.05). Moreover, it was observed that stress exposure and geraniol administration did not significantly affect hippocampal ACh levels (p>0.05). On the other hand, chronic stress significantly decreased AChE levels (p<0.05). Geraniol treatment did not significantly change AChE levels (p>0.05).

Conclusion: Taken together, our findings revealed that restraint stress induces depression-like behavior in rats, while geraniol treatment has antidepressant-like effects. However, we suggest that the molecular mechanism of the antidepressant-like effect of geraniol be investigated with further studies.