Investigating the effects of orexin receptors inhibition in the nucleus incertus on passive avoidance learning in male rats
Subject Areas :
F Eslami Saravi
1
,
E Akbari
2
,
V Babapour
3
*
,
M Zendehdel
4
1 - Department of Basic Sciences, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 - Department of Physiology and Pharmacology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
3 - Tehran University
4 - Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
Keywords: Orexin receptors, Nucleus incertus, Avoidance learning, Rat,
Abstract :
Learning and memory processes are influenced by various regions of the brain. The current study is designed to examine the effects of the inactivation of orexin receptors type 1 and 2 located in the NI of rat brains on the processing of avoidance learning and long-term potentiation (LTP). In different phases of this study, rats received dimethyl sulfoxide (DMSO, control group), orexin receptor type 1 antagonist (SB-334867-A), and orexin receptor type 2 antagonist (TCS-OX2-29) via cannula. Behavioral tests related to passive avoidance learning were conducted in two phases: consolidation and retrieval. Drug injections were administered immediately after training or 15 minutes before the start of the retrieval test in the NI. Additionally, in electrophysiological experiments, injections were performed 30 minutes prior to LTP induction to investigate the role of orexin receptors in LTP induction. The results indicated that the consolidation phase was significantly disrupted by antagonist injections in both behavioral tests (p < 0.05), while the retrieval phase was not affected (p ≥ 0.05). Furthermore, in electrophysiological testing, the amplitude of population spike (PS) experienced a significant reduction (p < 0.05), whereas the slope of the population excitatory postsynaptic potential (EPSP) did not change (p ≥ 0.05). Ultimately, this study demonstrated that the inhibition of orexin receptors type 1 and 2 in the NI leads to impairments in avoidance learning processes and synaptic long-term potentiation induction.
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