Melissa officinalis Interaction with Opioid Receptors Attenuates Stress-Induced Anxiety-Like and OCD-Like Behaviors

Melissa officinalis (MO) is a valuable medicinal herb from the Lamiaceae family, MO extracts possess different beneficial effects, including anti-inflammatory, antioxidant, memory enhancer, anxiolytic, and anti-depression. It seems that phytochemicals found in MO including flavonols (luteolin and apigenin) and polyphenols (rosmarinic acid and caffeic acid) are responsible for the beneficial effects of MO. The present study aimed to assess the role of opioid receptors in the effect of MO in anxiety and obsessive-compulsive disorder (OCD) in stressed rats. Male hooded rats received oral administration of MO (50, 100 and 200 mg/kg), with or without intraperitoneal injection of naloxone (1 mg/kg), and were exposed to 30 min stress, then anxiety-like and OCD-like behaviors were evaluated using light/dark box and marble burying test. Our results showed that oral administration of MO has anxiolytic effects and a reduction in OCD-like behavior in stressed rats that could be inhibited by injection of naloxone. On the other hand, in silico study showed that phytochemicals found in MO have a possible affinity for opioid receptors. Taken together, these data revealed that the opioid receptors may be involved in the anxiolytic effect of MO in stressed rats.