The Comparison of Intraventricular Injection of Mu Receptor Agonist (Morphine) and Antagonist (Naloxone) on the Occurrence of Fear Behavior in Adult Male Rats

Drugs are among the opioid-like compounds that lead to the development of emotional behaviors in humans and animals. One of the emotional behaviors is stress behavior caused by fear, which can be caused by opioid and quasi-opioid compounds. In this study, the effect of intraventricular injection of brain (I.C.V) agonist (morphine sulfate) and hair receptor antagonist (naloxone) on fear behavior in adult male Wistar rats was investigated.

In this study, pure harmalin was used as a hallucinogenic drug that causes hallucinations and fear in animals as a positive control and saline as a sham was used for comparative studies with groups treated with morphine sulfate and naloxone. In this study, stereotax machine was used for cannulation and injection of I.C.V and Elevated plus-maze machine was used for behavioral testing.

The values used to treat the experimental groups for morphine sulfate (0.5, 1, 2.5, 5, 7μg/rat) and naloxone (0.5, 1, 2μg/rat) were selected. The results of intraventricular injection of (1, 2.5, 5μg/rat) morphine in the brains of rats in the experimental group showed a significant difference in the occurrence of fear behavior compared to the positive control group with P <0.05.
While injection of values (0.5, 7μg/rat) did not show a significant difference with p <0.05 compared to the positive control group. Also, the results of intraventricular injection (I.C.V) of naloxone (1μg/rat) showed a significant difference with p <0.05 in the occurrence of fear behavior in comparison with the positive control group. While injection of values (0.5, 2.5μg/rat) did not show a significant difference with P <0.05 compared to the positive control group. In this study, I.C.V (50 μg / rat) injection of pure harmalin, which is considered as a positive control group, shows the percentage of entry into the open arm and also the percentage of retention time in the open arm.

In conclusion, none of the data used in the present study in the area has a uniform performance and this diversity can be considered as a result of various mechanisms that require more detailed studies.