Comparison of the Analgesic Effects of Royal Jelly with Morphine and Aspirin in Rats Using the Formalin

The side effects of synthetic analgesics in clinical use as well as patients’ growing interest in traditional medicine and natural products have drawn researchers’ attention to studying the effects of natural pain relievers and comparing them with chemical and synthetic drugs. Royal jelly, which is produced by bees to feed the queen bee, exerts anti-inflammatory effects through inhibiting the production of pre inflammatory cytokines by activated macrophages. This study aimed to compare the analgesic effects of morphine, aspirin and Royal Jelly as common painkillers. In this experimental study, 36 male Wistar rats were randomly classified into six groups of 6. The negative control group received the normal Saline of 5 kg/ml, one positive control group received morphine 2.5 mg/kg and the other received aspirin 300 mg/kg. The 3 treatment groups received Royal Jelly peritoneally with doses of 100, 200 and 400 mg/kg in single doses. Half an hour after the intraperitoneal injection, 50 micro liters of formalin 2.5% was subcutaneously injected into the bottom of the animals’ right paw and the analgesic effects were studied using the Formalin test. Our findings indicate that as a dose-dependent analgesic, Royal Jelly is most effective at a dose of 200 mg/kg. The grade of acute pain in the groups of Saline, aspirin, morphine and Royal Jelly (100, 200 and 400 kg) was 2.61±0.09, 1.56±0.06, 1.05±0.14, 2.40±0.08, 1.65±0.04 and 1.53±0.05, respectively. The grade of chronic pain in the same groups was 2.34±0.09, 1.28±0.12, 0.33±0.12, 2.15±0.07, 1.21±0.03 and 1.12±0.05, respectively. The analgesic effect of royal jelly with the dosage of 200 kg/mg on acute pain was approximately equal to that of aspirin and less than that of morphine. However, Royal Jelly was less effective on chronic pain than morphine and it did not differ significantly with aspirin. Given the prominent analgesic, antioxidant and anti-inflammatory qualities of royal jelly, this natural substance could be prescribed as a non-invasive method to reduce and relieve pain appropriately and applicably.