Effect of nicotine administration on physical and psychological signs of withdrawal syndrome induced by single or repeated doses of morphine in rat

Background and purpose: Morphine addiction and morphine withdrawal syndrome are of main problems in human societies. In the present study, effect of nicotine on the strength of physical and psychological dependency, produced by single and repeated doses of morphine, was investigated

Material and method: Male wistar rats were dependent to morphine with single and repeated dose protocols. In the single dose protocol, rats received only one dose of morphine and 24h later were given Naloxone. In the repeated dose protocol, rats received incremental doses of morphine for 7 days and 24h after the last dose [8th day] were given Naloxone. In the single dose protocol, rats were given one dose of nicotine 30 min before Naloxone. However in the repeated doses they received nicotine 15 min before morphine for 4 days from 4th day to 7th day. 5 min after Naloxone each rat?s behavior was captured for 30 min. then physical and psychological signs of withdrawal syndrome were recorded

Results: Results showed that injection of repeated and even single dose of morphine can produce dependency. Nicotine consumption attenuated strength of withdrawal syndrome signs, specially increasing weight excrement and total withdrawal score in single dose protocol and weight excrement increasing, weight decreasing, place aversion, and total withdrawal score in repeated dose treatment

Conclusion: Based on our data, even a single dose of morphine can produce dependency in rats. Conversely, Nicotine consumption attenuates strength of withdrawal syndrome signs

[Interaction between vitamin A and pilocarpine on memory retention in adult male rats]

Several studies have reported that retinoic acid administration and/or consumption of a vitamin A-enriched diet could repair the aging induced memory deficits, decreased hippocampal long term potentiation [LTP]. Vitamin A deficiency impairs learning ability and hippocampal LTP in mice. In the present study, the effects of the vitamin A and pilocarpine [a muscarinic agonist] on memory retention in adult male rats were investigated. Post-training intracerebroventricular injections were carried out in all experiments. Memory retention was evaluated by using a step-through passive avoidance paradigm in adult male rats. Vitamin A [1000 and 2000 IU/rat] and pilocarpine [1 microg/rat] increased memory retention. The acetylcholine receptor agonist [pilocarpine] increased the response to vitamin A. The response to vitamin A was potentiated by pilocarpine. It is concluded that vitamin A elicits an interaction with the cholinergic system in memory retention

Involvement of the nucleus accumbensshell presynaptic NMDA receptors on anxiolytic-like behaviors induced by NMDA in adult male Wistar rat

Glutamatergic system stimulationthe nucleus accumbens shell, may affect anxiety-related behaviors, aversive learning and memory. Glutamate receptors are differentially distributed in pre- and postsynaptic sites contributing to neuronal communications.The present study aimed to examine the possible involvement of the NAc shell presynaptic NMDA receptors on NMDA induced responses, using the elevated-plus maze [EPM] task in maleWistar rats. Bilateral guide cannulae were implanted to allow microinjection of glutamatergic agonist [NMDA] or ca+2 channel blocker [SKF96365 hydrochloride] agents. Pretest intra-NAc shell infusion of NMDA induced anxiolytic-like behaviors and impaired the EPM-associated memory upon test and retest, respectively. In addition our findings showed that, the intra-NAc shell infusion of Ca+2 channel blocker at applied doses, does not alter the anxiety-like response and aversive memory upon test and retest, respectively. Furthermore, infusing the subthreshold dose SKF prior to the injection of effective doses of NMDA, reduced the anxiolytic-like response and improved the aversive memory impairment which had already been induced by intra-NAc shell NMDA injection. Our study showed that,inhibition of the neurotransmitter exocytosis from pre-synaptic neuron via Ca+2 channel blockade bySKF96365 decreases affected induced by NMDA in the NAc shell region, indicating the involvement of the pre-synaptic NMDA receptors in NMDA induced responses.Therefore, NMDA's ability to increase anxiolytic-like behaviors and the aversive memory impairment may be the result of an action on pre-synaptic glutamatergic receptors which in turn decrease the glutamate effect at synaptic terminal level

effect of nicotine administration on physical and psychological signs of withdrawal syndrome induced by single or frequent doses of morphine in rats

Morphine addiction and morphine withdrawal syndrome are the two main problems of today's human society. The present study has investigated the effects of nicotine on the strength of physical and psychological dependency in single and repeated doses morphine administrated rats. Male Wistar rats were subjected to morphine consumption with single or frequent dose protocols. In the single dose protocol, rats received only one dose of morphine and 24hrs later they also received one dose of nicotine 30 min prior to injection of naloxone. In the repeated dose protocol, rats received incremental doses of morphine for 7 days and 24hr after the last dose [the 8th day] were given naloxone. However, the nicotine regimen of this group was injected 15 min before the morphine injection, for 4 days, from the 4th to the 7th day. Five minutes after naloxone injection, each rat's behavior was captured for 30 min, and then physical and psychological signs of withdrawal syndrome were recorded. Data were analyzed by ANOVA followed by Tukey tests and p<0.05 was considered as significant difference. Results showed that the injection of frequent and single doses of morphine lead to morphine dependency. In single dose protocol, nicotine consumption attenuated the signs of withdrawal syndrome, especially weight of excrement and total withdrawal score. In frequent dose protocol, in addition to these effects, nicotine induced weight loss and place aversion. The inhibitory effects of nicotine on signs of withdrawal syndrome may involve a dopaminergic portion of the central nervous system and is mediated by central nicotinic receptors. There is also a cross-dependence between nicotine and morphine

Microinjection of dihydrotestosterone as a 5 alpha-reduced metabolite of testosterone into CA1 region of hippocampus could improve spatial learning in the adult male rats

CA1 region of hippocampus has an important role in learning and memory. Previous reports have shown that androgens like testosterone and its metabolites are present in high concentration in CA1 region of hippocampus. Androgen receptors have also high density in this region. Therefore, it is suggested that neurohormones in CA1 have an important role in learning and memory. It is likely that testosterone exerts its effect via its metabolites, especially dihydrotestosterone [DHT], a 5alpha-reduced androgen. In this research, we conducted an experiment to assess the path of testosterone_s effectiveness on spatial learning and memory. Adult male rats were randomly divided into 4 groups and, bilaterally, cannulated into CA1 region of hippocampus. One week after the surgery, animals received DMSO 0.5 microL as a control group and different doses of dihydrotestosterone [DHT] [0.25, 0.5 and 1 microg/0.5 microL/side] 25-30 min before the training in spatial version of Morris Water Maze task. Training session contained two blocks which animals had to learn the position of hidden platform in 4 trials. On the test session [next day], rats performed a one-trial probe test and then a visible platform one. The results showed that escape latency and traveled distance were decreased significantly in DHT-treated [0.5 microg/0.5 microL/side] rats. This finding suggested that DHT may have improved the effect on acquisition of spatial learning and memory