introduction: drugs of abuse such as nicotine and morphine used systemically by addicts produce their effects via the mesolimbic dopaminergic pathway. furthermore, evidence indicates that some behavioral effects of nicotine and morphine are mediated by nitric oxide (no). based on these observations, the aim of the present study was to investigate the effects of intra-nucleus accumbens (nac) inj...

BACKGROUND Learning and memory processes can be affected by morphine administration. It has been previously demonstrated that the effects of morphine depend on the timing of drug administration. In the present study, the effects of microinjections of a NMDA receptor agonist and antagonist into the CA1 regions of the dorsal hippocampi (intra-CA1) on repeated pretreatment of morphine-induced prev...

Introduction: Drugs of abuse such as nicotine and morphine used systemically by addicts produce their effects via the mesolimbic dopaminergic pathway. Furthermore, evidence indicates that some behavioral effects of nicotine and morphine are mediated by nitric oxide (NO). Based on these observations, the aim of the present study was to investigate the effects of intra-nucleus accumbens (NAc) ...

Five experiments studied retrograde impairments in Pavlovian fear conditioning following prolonged exposure to the opioid receptor agonist morphine. Injections of morphine commencing 1-7 days but not 14 days after conditioning produced amnesia for that conditioning episode. This amnesia was (a) selective such that morphine impaired freezing to the conditioning context but not to the auditory co...

morphine’s effects on learning and memory processes are well known to depend on synaptic plasticity in the hippocampus. whereas the role of the hippocampus in morphine-induced amnesia and state-dependent learning is established, the biochemical and molecular mechanisms underlying these processes are poorly understood. the present study intended to investigate whether administration of morphine ...

In the present study, the effects of morphine sensitization on morphine-induced impairment of memory formation and the state-dependent retrieval of a passive avoidance task learned under morphine influence have been investigated in mice. Pre-training administration of morphine (0.5, 2.5 and 5 mg/kg) dose dependently suppressed the learning of one-trial passive avoidance task. Pre-test administr...

In the present study, the effects of morphine sensitization on morphine-induced impairment of memory formation and the state-dependent retrieval of a passive avoidance task learned under morphine influence have been investigated in mice. Pre-training administration of morphine (0.5, 2.5 and 5 mg/kg) dose dependently suppressed the learning of one-trial passive avoidance task. Pre-test administr...

Background: Morphine is wildly used as a painkiller in clinics, but causes several side effects such as hyperalgesia, depression and more notably amnesia. Here, we assumed that insulin-like Growth Factor-1 (IGF-1) as a peptide with widespread distribution of receptors in brain regions, especially hippocampus, might be capable to alleviate morphine-induced amnesia. Meth...

Introduction: Learning and memory processes result from interaction of neurotransmitter systems in various brain regions such as amygdala and hippocampus. Considering that morphine induces memory impairment, in the current study, we examined the possible role of cholinergic muscarinic receptors of the central amygdala (CeA) on the morphine-induced amnesia in adult male Wistar rats. Methods...