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Involvement of dorsal hippocampal nicotinic receptors in the effect of morphine on memory retrieval in passive avoidance task.
Eur J Pharmacol. 2008 Apr 28; 584(2-3):343-51.EJ

Abstract

The present study evaluated the possible role of nicotinic acetylcholine receptors of the dorsal hippocampus on morphine-induced amnesia and morphine state-dependent memory in adult male Wistar rats. The animals were bilaterally implanted with chronic cannulas in the CA1 regions of the dorsal hippocampi, trained in a step-through type passive avoidance task, and tested 24 h after training to measure step-through latency. Results indicate that post-training subcutaneous (s.c.) administration of morphine (2.5-7.5 mg/kg) dose-dependently reduced the step-through latency, showing an amnestic response. Post-training intra-CA1 microinjection of nicotine (0.5-1 microg/rat) decreased significantly the amnesia induced by post-training morphine (7.5 mg/kg). Moreover, co-treatment of mecamylamine (0.5 and 1 microg/rat, intra-CA1) with an ineffective dose of morphine (2.5 mg/kg), immediately after training, caused inhibition of memory retrieval. On the other hand, amnesia produced by post-training morphine (7.5 mg/kg) was reversed by pre-test administration of the opioid that is due to a state-dependent effect. Interestingly, pre-test intra-CA1 microinjection of nicotine (0.25 and 0.5 microg/rat) improved post-training morphine (7.5 mg/kg)-induced retrieval impairment. Moreover, pre-test administration of the same doses of nicotine in combination with a lower dose of morphine (0.5 mg/kg), which had no effects alone, synergistically improved memory performance impaired by post-training morphine. Pre-test injection of mecamylamine (0.5-2 microg/rat) prevented the restoration of memory by pre-test morphine. It is important to note that post-training or pre-test intra-CA1 administration of the same doses of nicotine or mecamylamine, alone did not affect memory retrieval. These results suggest that nicotinic acetylcholine receptors of the hippocampal CA1 regions may play an important role in morphine-induced amnesia and morphine state-dependent memory.

Authors+Show Affiliations

Department of Animal Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18316071

Citation

Khajehpour, Lotfollah, et al. "Involvement of Dorsal Hippocampal Nicotinic Receptors in the Effect of Morphine On Memory Retrieval in Passive Avoidance Task." European Journal of Pharmacology, vol. 584, no. 2-3, 2008, pp. 343-51.
Khajehpour L, Rezayof A, Zarrindast MR. Involvement of dorsal hippocampal nicotinic receptors in the effect of morphine on memory retrieval in passive avoidance task. Eur J Pharmacol. 2008;584(2-3):343-51.
Khajehpour, L., Rezayof, A., & Zarrindast, M. R. (2008). Involvement of dorsal hippocampal nicotinic receptors in the effect of morphine on memory retrieval in passive avoidance task. European Journal of Pharmacology, 584(2-3), 343-51. https://doi.org/10.1016/j.ejphar.2008.02.030
Khajehpour L, Rezayof A, Zarrindast MR. Involvement of Dorsal Hippocampal Nicotinic Receptors in the Effect of Morphine On Memory Retrieval in Passive Avoidance Task. Eur J Pharmacol. 2008 Apr 28;584(2-3):343-51. PubMed PMID: 18316071.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Involvement of dorsal hippocampal nicotinic receptors in the effect of morphine on memory retrieval in passive avoidance task. AU - Khajehpour,Lotfollah, AU - Rezayof,Ameneh, AU - Zarrindast,Mohammad-Reza, Y1 - 2008/02/19/ PY - 2007/11/14/received PY - 2008/01/30/revised PY - 2008/02/13/accepted PY - 2008/3/5/pubmed PY - 2008/7/2/medline PY - 2008/3/5/entrez SP - 343 EP - 51 JF - European journal of pharmacology JO - Eur J Pharmacol VL - 584 IS - 2-3 N2 - The present study evaluated the possible role of nicotinic acetylcholine receptors of the dorsal hippocampus on morphine-induced amnesia and morphine state-dependent memory in adult male Wistar rats. The animals were bilaterally implanted with chronic cannulas in the CA1 regions of the dorsal hippocampi, trained in a step-through type passive avoidance task, and tested 24 h after training to measure step-through latency. Results indicate that post-training subcutaneous (s.c.) administration of morphine (2.5-7.5 mg/kg) dose-dependently reduced the step-through latency, showing an amnestic response. Post-training intra-CA1 microinjection of nicotine (0.5-1 microg/rat) decreased significantly the amnesia induced by post-training morphine (7.5 mg/kg). Moreover, co-treatment of mecamylamine (0.5 and 1 microg/rat, intra-CA1) with an ineffective dose of morphine (2.5 mg/kg), immediately after training, caused inhibition of memory retrieval. On the other hand, amnesia produced by post-training morphine (7.5 mg/kg) was reversed by pre-test administration of the opioid that is due to a state-dependent effect. Interestingly, pre-test intra-CA1 microinjection of nicotine (0.25 and 0.5 microg/rat) improved post-training morphine (7.5 mg/kg)-induced retrieval impairment. Moreover, pre-test administration of the same doses of nicotine in combination with a lower dose of morphine (0.5 mg/kg), which had no effects alone, synergistically improved memory performance impaired by post-training morphine. Pre-test injection of mecamylamine (0.5-2 microg/rat) prevented the restoration of memory by pre-test morphine. It is important to note that post-training or pre-test intra-CA1 administration of the same doses of nicotine or mecamylamine, alone did not affect memory retrieval. These results suggest that nicotinic acetylcholine receptors of the hippocampal CA1 regions may play an important role in morphine-induced amnesia and morphine state-dependent memory. SN - 0014-2999 UR - https://www.unboundmedicine.com/medline/citation/18316071/Involvement_of_dorsal_hippocampal_nicotinic_receptors_in_the_effect_of_morphine_on_memory_retrieval_in_passive_avoidance_task_ DB - PRIME DP - Unbound Medicine ER -