Alcohol: Epigenome alteration and inter/transgenerational effect

While DNA serves as the fundamental genetic blueprint for an organism, it is not a static entity. Gene expression, the process by which genetic information is utilized to create functional products like proteins, can be modulated by a diverse range of environmental factors. Epigenetic mechanisms, including DNA methylation, histone modification, and microRNAs, play a pivotal role in mediating the intricate interplay between the environment and gene expression. Intriguingly, alterations in the epigenome have the potential to be inherited across generations. Alcohol use disorder (AUD) poses significant health issues worldwide. Alcohol has the capability to induce changes in the epigenome, which can be inherited by offspring, thus impacting them even in the absence of direct alcohol exposure. This review delves into the impact of alcohol on the epigenome, examining how its effects vary based on factors such as the age of exposure (adolescence or adulthood), the duration of exposure (chronic or acute), and the specific sample collected (brain, blood, or sperm). The literature underscores that alcohol exposure can elicit diverse effects on the epigenome during different life stages. Furthermore, compelling evidence from human and animal studies demonstrates that alcohol induces alterations in epigenome content, affecting both the brain and blood. Notably, rodent studies suggest that these epigenetic changes can result in lasting phenotype alterations that extend across at least two generations. In conclusion, the comprehensive literature analysis supports the notion that alcohol exposure induces lasting epigenetic alterations, influencing the behavior and health of future generations. This knowledge emphasizes the significance of addressing the potential transgenerational effects of alcohol and highlights the importance of preventive measures to minimize the adverse impact on offspring.

The effect of morphine administration on GluN3B NMDA receptor subunit mRNA expression in rat brain

Opioid addiction is critically dependent on the activation of N‑methyl‑D‑aspartate (NMDA) receptors, which are widely found in the mesocorticolimbic system. Meanwhile, opioid addiction may affect the expression level of NMDA receptor subunits. The existence of GluN3 subunits in the NMDA receptor's tetramer structure reduces the excitatory current of the receptor channel. We evaluated the changes in the mRNA expression pattern of the GluN3B subunit of the NMDA receptor in rat brains following acute and chronic exposure to morphine. Chronic, escalating intraperitoneal doses of morphine or saline were administered twice daily to male Wistar rats for six days. Two other groups were injected with a single acute dose of morphine or saline. The mRNA level of the GluN3B subunit of the NMDA receptor in the striatum, hippocampus, and nucleus accumbens (NAc) was measured by real‑time PCR. mRNA expression of the GluN3B subunit was considerably augmented (3.15 fold) in the NAc of animals chronically treated with morphine compared to the control group. The difference between rats that were chronically administered morphine and control rats was not statistically significant for other evaluated brain areas. In rats acutely treated with morphine, no significant differences were found for GluN3B subunit expression in the examined brain regions compared to the control group. It was concluded that chronic exposure to morphine notably increased the GluN3B subunit of the NMDA receptor in NAc. The extent of the impact of this finding on opioid addiction and its features requires further evaluation in future studies.

The role of lateral habenula NMDA receptors in tramadol-induced conditioning

The role of the lateral habenula (LHb) as a hub for receiving and relaying signals from the limbic system to serotonergic, dopaminergic, and norepinephrinergic regions in the brainstem makes this area a critical region in the control of reward and addiction. Behavioral evidence reveals the vital role of the LHb in negative symptoms during withdrawal. In this investigation, we study the role of the LHb N-Methyl D-Aspartate receptor (NMDAR) in the modulation of tramadol reward. Male adult Wistar rats were used in this study. The effect of intra-LHb micro-injection of NMDAR agonist (NMDA, 0.1, 0.5, 2 µg/rat) and antagonist (D-AP5, 0.1, 0.5, 1 µg/rat) was evaluated in conditioned place preference (CPP) paradigm. The obtained results showed that intra-LHb administration of NMDA induced place aversion dose-dependently, while blockade of NMDAR in the LHb using D-AP5 micro-injection led to an increased preference score in the CPP task. Co-administration of NMDA (0.5 µg/rat) with tramadol (4 mg/kg) reduced preference score, while co-administration of D-AP5 (0.5 µg/rat) with a non-effective dose of tramadol (1 mg/kg) potentiate the rewarding effect of tramadol. LHb receives inputs from the limbic system and projects to the monoaminergic nuclei in the brainstem. It has been declared that NMDAR is expressed in LHb, and as obtained data revealed, these receptors could modulate the rewarding effect of tramadol. Therefore, NMDA receptors in the LHb might be a new target for modulating tramadol abuse.

Does Morphine Exposure Before Gestation Change Anxiety-Like Behavior During Morphine Dependence in Male Wistar Rats?

Background

Anxiety is one of the comorbid disorders of opioid addiction, which leads to opioid abuse or persuades people to engage in opioid abuse. Evidence revealed that morphine exposure before conception changes the offspring's phenotype. The current study aimed to investigate the influence of morphine dependence and abstinence on anxiety-like behavior in morphine-exposed and drug-naïve offspring.

Methods

Adult male and female rats were treated with morphine or vehicle for 21 days. Then, all rats were left without drug treatment for 10 days. A morphine-exposed female rat was mated with either a vehicle-exposed or morphine-abstinent male. According to parental morphine exposure, the offspring were categorized into four distinct groups: (1) control (both drug-naïve parents), (2) paternal morphine-exposed, (3) maternal morphine-exposed, and (4) biparental morphine-exposed. The anxiety-like behavior was measured in adult male offspring using open field and elevated plus-maze tests before morphine exposure (naïve), 21 days after morphine exposure (dependence), and ten days after the last morphine exposure (abstinence).

Findings

The results indicated that anxiety-like behavior increased before morphine exposure in maternal and biparental morphine-exposed offspring (P<0.05). However, after morphine exposure, the anxiety level did not change among the groups. Ten days after the last morphine exposure, anxiety-like behavior increased only in biparental morphine-exposed offspring (P<0.05).

Conclusion

The offspring of morphine-abstinent parents exhibited an anxious phenotype. Disruption of the HPA axis was seen in the progeny of maternal and biparental morphine-exposed rats. Indeed, morphine exposure for 21 days did not change anxiety-like behavior in these offspring which might be correlated to disruption of HPA axis in them.

Inter/Transgenerational Effects of Drugs of Abuse: A Scoping Review

Drug addiction is a chronic relapsing disorder that makes it a global problem. Genetics and environmental factors are the two most important factors that make someone vulnerable to drug addiction. Investigations in the past decade highlighted the role of epigenetics in the inter/transgenerational inheritance of drug addiction. A growing body of evidence showed that parental (paternal, maternal, and biparental) drug exposure before conception changes the phenotype of the offspring, which is correlated with neurochemical and neurostructural changes in the brain. The current paper reviews the effects of parental (maternal, paternal, and biparental) exposure to drugs of abuse (opioids, cocaine, nicotine, alcohol, and cannabis) before gestation in animal models.

Effect of tramadol on apoptosis and synaptogenesis in hippocampal neurons: The possible role of µ-opioid receptor

Tramadol is a synthetic opioid with centrally acting analgesic activity that alleviates moderate to severe pain and treats withdrawal symptoms of the other opioids. Like other opioid drugs, tramadol abuse has adverse effects on central nervous system components. Chronic administration of tramadol induces maladaptive plasticity in brain structures responsible for cognitive function, such as the hippocampus. However, the mechanisms by which tramadol induces these alternations are not entirely understood. Here, we examine the effect of tramadol on apoptosis and synaptogenesis of hippocampal neuronal in vitro. First, the primary culture of hippocampal neurons from neonatal rats was established, and the purity of the neuronal cells was verified by immunofluorescent staining. To evaluate the effect of tramadol on neuronal cell viability MTT assay was carried out. The western blot analysis technique was performed for the assessment of apoptosis and synaptogenesis markers. Results show that chronic exposure to tramadol reduces cell viability of neuronal cells and naloxone reverses this effect. Also, the level of caspase-3 significantly increased in tramadol-exposed hippocampal neurons. Moreover, tramadol downregulates protein levels of synaptophysin and stathmin as synaptogenesis markers. Interestingly, the effects of tramadol were abrogated by naloxone treatment. These findings suggest that tramadol can induce neurotoxicity in hippocampal neuronal cells, and this effect was partly mediated through opioid receptors.

Tannic acid protects aged brain against cerebral hypoperfusion via modulation of Nrf2 and inflammatory pathways

Current study purposed to investigate the neuroprotective effects of Tannic Acid (TA) on mild chronic cerebral hypoperfusion model in rats. Male Wistar rats were subjected to permanent Unilateral Common Carotid Artery Occlusion (UCCAO), followed by TA treatment (0.05% w/v) in drinking water for one month. Nuclear factor erythroid 2-related factor 2 (Nrf2), NAD(P)H: quinone oxidoreductase 1 (NQO-1), heme oxygenase-1 (HO-1), factor kappa-light-chain-enhancer of activated B cells (NF-κB), tumor necrosis factor-α (TNF-α), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3, blood triglyceride, blood glucose, and liver enzymes' activity were detected after the experimental period. Also, behavioral tests, hematoxylin and eosin (H&E) staining, and PET scan were performed after treatment. Post-treatment of TA improved locomotion and memory function (P < 0.001), and reduced neural cell death (P < 0.001) in the treatment group compared to UCCAO rats. Furthermore, long-term TA treatment significantly increased the levels of Nrf2 (P < 0.001), NQO-1 (P < 0.001), and HO-1 (P < 0.001) in the hippocampus of the treatment group compared to the UCCAO group. TA consumption in the treatment group applied its anti-inflammatory effects via reducing the activity of NF-κB and TNF-α in comparison with the UCCAO group (P < 0.001 for both). Blood triglyceride, blood glucose, and liver enzymes did not change considerably in the groups (P > 0.05). The current results indicate that long-term post-treatment of TA exhibits protective effects against memory deficit and motor dysfunction. The cellular mechanism of TA in hypoperfused rats might be associated with the activation of antioxidant pathways, especially the Nrf2 pathway, and suppressing inflammatory factors like NF-κB and TNF-α.

Altered D2 receptor and transcription factor EB expression in offspring of aggressive male rats, along with having depressive and anxiety-like behaviors

MATERIALS AND METHODS

In this study we have evaluated the behavioral mood variations, and expression of DR-D2 and TFEB genes in the amygdala and PFC of aggressive male rats' offspring.

RESULTS

Anxiety and depression-like behaviors were observed, but intra-ventricle injection of DR-D2 antagonist (Sulpiride) has shown to be efficient in reducing negative behavioral changes in offspring. Furthermore, DR-D2 gene expression was increased in the amygdala and PFC of aggressive male rats' offspring, which the injection of Sulpiride decreased it significantly. TFEB gene expression was also decreased in the amygdala and PFC of aggressive male rats' offspring, but the blockade of DR-D2 had no effect on it.

CONCLUSIONS

The current data suggests the possible influence of dopaminergic receptors D2 and TFEB genes on the behavioral changes which is modified by having an aggressive father.

Effects of Morphine and Maternal Care on Behaviors and Protein Expression of Male Offspring

Genes and environment interact during development to alter gene expression and behavior. Parental morphine exposure before conception has devastating effects on the offspring. In the present study, we evaluated the role of maternal care in the intergenerational effect of maternal morphine exposure. Female rats received morphine or saline for ten days and were drugfree for another ten days. Thereafter, they were allowed to mate with drug-naïve male rats. When pups were born, they were cross-fostered to assess the contribution of maternal care versus morphine effects on the offspring. Adult male offspring were examined for anxiety-like behavior, spatial memory, and obsessive-compulsive-like behavior. To determine the mechanisms underlying the observed behavioral changes, protein levels of acetylated histone H3, BDNF, Trk-B, NMDA subunits, p-CREB, and 5-HT₃R were measured in the brain. Our results indicate that maternal caregiving is impaired in morphine-abstinent mothers. Interestingly, maternal care behaviors were also affected in drug-naïve mothers that raised offspring of morphine-exposed mothers. In addition, the offspring of morphine abstinent and non-drug dependent mothers, when raised by morphine abstinent mothers, exhibited more anxiety, obsessive-compulsive behaviors and impaired spatial memory. These altered behaviors were associated with alterations in the levels of the above-mentioned proteins. These data illustrate the intergenerational effects of maternal morphine exposure on offspring behaviors. Moreover, exposure to morphine before gestation not only affects maternal care and offspring behavior, but also has negative consequences on behaviors and protein expression in adoptive mothers of affected offspring.

Comparison and interaction of morphine and CB1 agonist conditioned place preference in the rat model of early life stress

Early life stress (ELS) disrupts brain development and subsequently affects physical and psychological health. ELS has been associated with an increased risk of relapse and inadequate treatment response in addicted patients. The current study was designed to find the effect of ELS on the rewarding effect of morphine and cannabinoid and their interaction. Pregnant female Wistar rats were used in this study. On postnatal day 2 (PND2), pups were separated from their mothers for 3 hr daily. This procedure was repeated every day at the same time until PND 14. The control group was kept in the standard nesting way with their mothers. The adult male offspring of maternal separated (MS) and standard nested (SN) rats were used. Using conditioned place preference task (CPP), the rewarding effect of morphine (0.75, 1.25, 2.5, and 5 mg/kg) was evaluated in both MS and SN groups. Besides, the rewarding effect of cannabinoids was investigated using the administration of CB1 receptor agonist (ACPA, 0.25, 0.5, 1 µg/rat) and inverse agonist (AM-251, 30, 60, and 90 ng/rat) in the nucleus accumbens (NAc). To evaluate the interaction between NAc cannabinoidergic system and morphine, the noneffective dose of ACPA and AM-251 were administered with a noneffective dose of morphine (0.75 mg/kg) on both MS and SN animals. Obtained results indicated that MS groups had a leftward shift in the rewarding effect of morphine and conditioned with low doses of morphine. However, they had a rightward shift in the rewarding effect of cannabinoids. In addition, coadministration of noneffective doses of morphine and ACPA potentiate conditioning in both MS and SN groups. Previous evidence shows that ELS induced changes in the brain, especially in the reward circuits. Here, we demonstrated that MS animals are more sensitive to the rewarding effect of morphine compared with SN animals. In addition, ELS disrupts the cannabinoid system and affect the rewarding effect of cannabinoids.

Alteration of orexin-A and PKCα in the postmortem brain of pure-opioid and multi-drug abusers

Finding changes induced by the drug of abuse is one of the most important approaches to design new drugs for the treatment of substance use disorders (SUD). Postmortem study is the most reliable method for detecting alteration in the brain of SUD patients. Recently, the role of orexinergic system in SUD is in consideration. In the current study, we evaluated the level of orexin-A in the CSF and protein kinase Cα (PKCα) in the brain of pure-opioid (POA) and multi-drug abusers (MDA). A total of 56 POA, 45 MDA, and 13 matched control brains were collected from the legal medicine center, Tehran, Iran. The CSF was gathered from the third ventricle immediately after opening the skull and kept at -80 °C. The medial prefrontal cortex (mPFC), lateral prefrontal cortex (lPFC), orbitofrontal cortex (OFC), nucleus accumbens (NAc), and amygdala were dissected from fresh brain, frozen with liquid nitrogen and kept at -80 °C. The level of orexin-A evaluated in the CSF. Using western blotting, the level of PKCα assessed in the brain. Obtained data revealed that the level of orexin-A increased in POA and MDA compared with the control group (p < 0.05). In addition, the level of PKCα increased in the prefrontal cortex and amygdala of the abusers compared with the control group, although we did not detect changes in the level of PKCα in the NAc. Along with animal studies, the current results showed that the level of orexin increased in the CSF of drug abusers, which might be related to increases in the activation of lateral hypothalamic orexinergic neurons faced with the drug of abuse. Enhancement in the level of PKCα in the drug reward circuits might be adaptational changes induced by orexin and drugs of abuse.

Toxic effect of calcium/calmodulin kinase II on anxiety behavior, neuronal firing and plasticity in the male offspring of morphine-abstinent rats

Studies have shown that epigenetic changes such as alteration in histone acetylation and DNA methylation in various brain regions play an essential role in anxiety behavior. According to the critical role of calcium/calmodulin protein kinaseII (CaMKII) in these processes, the present study examined the effect of CaMKII inhibitor (KN93) on neuronal activity and level of c-fos in the amygdala and nucleus accumbens (NAC) in the offspring of morphine-exposed parents. Adult male and female Wistar rats received morphine orally (for 21 days). After the washout period (10 days), rats were mated with either drug-naïve or morphine-exposed rats. KN93 was microinjected into the brain of male offspring. The anxiety-like behavior, the neuronal firing rate in the NAC and the amygdala and level of c-fos were assessed by related techniques. Data showed the offspring with one and/or two morphine-abstinent parent(s) had more anxiety-like behavior than the control group. However, the administration of KN-93 decreased anxiety in the offspring of morphine-exposed rats compared with saline-treated groups. The expression level of the c-fos was not significantly altered by the inhibition of CaMKII in the amygdala, but the c-fos level was reduced in the NAC. The neuronal firing rate of these groups was associated with an increase in the amygdala in comparison to the saline groups but was decreased in the NAC. Results showed that CaMKII had a role in anxiety-like behavior in the offspring of morphine-exposed parents, and changes in neuronal firing rate and c-fos level in the NAC might be involved in this process.

Effect of morphine exposure on novel object memory of the offspring: The role of histone H3 and ΔFosB

It has been demonstrated that alteration in histone acetylation in the regions of the brain involved in the reward which may have an important role in morphine addiction. It is well established that epigenetic changes prior to birth influence the function and development of the brain. The current study was designed to evaluate changes in novel object memory, histone acetylation and ΔFosB in the brain of the offspring of morphine-withdrawn parents. Male and female Wistar rats received morphine orally for 21 following days. After ten days of abstinent, they were prepared for mating. The male offspring of the first parturition were euthanized on postnatal days 5, 21, 30 and 60. The novel object recognition (NOR) test was performed on adult male offspring. The amount of acetylated histone H3 and ΔFosB were evaluated in the prefrontal cortex (PFC) and hippocampus using western blotting. Obtained results indicated that the discrimination index in the NOR test was decreased in the offspring of morphine-withdrawn parents as compared with morphine-naïve offspring. In addition, the level of acetylated histone H3 was decreased in the PFC and hippocampus in the offspring of morphine-withdrawn parents during lifetime (postnatal days 5, 21, 30 and 60). In the case of ΔFosB, it also decreased in these regions in the morphine-withdrawn offspring. These results demonstrated that parental morphine exposure affects NOR memory, and decreased the level of histone H3 acetylation and ΔFosB in the PFC and hippocampus. Taken together, the effect of morphine might be transmitted to the next generation even after stop consuming morphine.

Oxidative stress enzymes are changed in opioid abusers and multidrug abusers

The current study was designed to measure malondialdehyde level (MDA), super oxide dismutase (SOD) activity and COX-2 protein level in the prefrontal cortex (PFC) of drug-abusers. A total of 101 male drug abusers and 13 control subjects were gathered from the Iranian Legal Medicine center, Kahrizak, Tehran. Kind of death was determined by forensic pathologists, and the kind of drugs of abuse was detected using hair analysis. The medial prefrontal cortex (mPFC), lateral prefrontal cortex (lPFC), and orbitofrontal cortex (OFC) were dissected and were kept at -80 °C, until starting the assays. Our results indicated that the level of MDA was increased in the mPFC, lPFC and OFC of pure-opioid and multi-drug abusers compared with the control group. The SOD activity was reduced in the mPFC, lPFC and OFC of abusers in comparison to the control group. The protein level of COX-2 was decreased in the mPFC and lPFC of multi-drug abusers compared with the control group. This elevation in oxidative stress might be due to the increase of dopamine (as a consequence of drug abuse) or the direct effect of opioids and other drugs of abuse on oxidative agents. Antioxidant agents may be useful in preventing the damaging effect of oxidative agents in the brain of drug-addicted persons.

Evaluation of dynorphin and kappa-opioid receptor level in the human blood lymphocytes and plasma: Possible role as a biomarker in severe opioid use disorder

BACKGROUND

The dynorphin (DYN)/kappa opioid receptor (KOR) system plays an important role in the development of addiction, and dysregulation of this system could lead to abnormal activity in the reward pathway. It has been reported that the expression state of the neurotransmitters and their receptors in the brain is reflected in peripheral blood lymphocytes (PBLs).

METHODS

We have evaluated the PBLs and plasma samples of four groups: 1) subjects with severe opioid use disorder (SOD), 2) methadone-maintenance treated (MMT) individuals, 3) long-term abstinent subjects having former SOD, and 4) healthy control subjects (n = 20 in each group). The mRNA expression level of preprodynorphin (pPDYN) and KOR in PBLs has been evaluated by real-time PCR. Peptide expression of PDYN in PBLs has been studied by western blot, and DYN concentration in plasma has been measured by ELISA.

RESULTS

The relative expression level of the pPDYN mRNA and PDYN peptide in PBLs were significantly up-regulated in SOD, MMT, and abstinent groups compared to control subjects. No significant difference was found in the plasma DYN concentration between study groups. The expression level of the KOR mRNA in PBLs was significantly decreased in all three study groups compared to the control subjects.

CONCLUSION

the expression changes in the DYN/KOR system after chronic exposure to opioids, including methadone, seems to be stable and does not return to normal levels even after 12 months abstinence. These long-time and permanent changes in PBLs may serve as a biomarker and footprint of SOD development in the periphery.

Transgenerational influence of parental morphine exposure on pain perception, anxiety-like behavior and passive avoidance memory among male and female offspring of Wistar rats

Accumulating evidence suggests that epigenetic mechanisms play an important role in the formation and maintenance of memory within the brain. Moreover, the effect of parental drug-exposure before gestation on behavioral state of offspring has been little studied. The main objective of the current study is to evaluate the effect of parental morphine exposure on avoidance memory, morphine preference and anxiety-like behavior of offspring. The total of 32 males and 32 females were used for mating. The animals were treated with morphine. The offspring according to their parental morphine treatment was divided into four groups (n=16) including paternally treated, maternally treated, both of parents treated and naïve animals. The pain perception, anxiety-like behavior, and avoidance memory were evaluated in the offspring. In the current study, the total of 256 offspring was used for the experiments (4 tasks × 4 groups of offspring × 8 female offspring × 8 male offspring). The finding revealed that the avoidance memory and visceral pain were reduced significantly in male and female offspring with at least one morphine-treated parent. Moreover, anxiety-like behavior was reduced significantly in the male offspring with at least one morphine-treated parent. While anxiety-like behavior was increased significantly in female offspring that were treated by morphine either maternally or both of parents. The data revealed that the endogenous opioid system may be altered in the offspring of morphine-treated parent(s), and epigenetic role could be important. However, analysis of variance signified the important role of maternal inheritance.

Parental morphine exposure affects repetitive grooming actions and marble burying behavior in the offspring: Potential relevance for obsessive-compulsive like behavior

Family, adoption and twin studies have highlighted the significant role of heritable influences on individual differences in opioid addiction. Meanwhile, obsessive-compulsive disorder (OCD) is a disorder wherein the individual experiences recurring thoughts that cause irrational fears and anxiety. In the present study, adult male and female rats received morphine solution for 21 days and were drug-free for 10 days. Offspring were used in 4 distinct groups; (1) paternal morphine-exposed, (2) maternal morphine-exposed, (3) maternal and paternal morphine-exposed, and (4) drug-naïve subjects. We assessed the grooming behavior and marble burying test as an indicator of obsessive-compulsive behavior. To clarify the mechanisms underlying these changes, the mRNA level of BDNF, the phosphorylation level of CREB and the protein level of D2 dopamine receptor (DR) were evaluated in the nucleus accumbens (NAc). The grooming behavior in male offspring with one or two morphine-abstinent parent(s) increased compared with the offspring of drug naïve rats. In addition, the offspring of morphine-exposed parents buried more marbles when compared with the offspring of drug-naïve parents. Also, the BDNF mRNA was down-regulated in the NAC. However, the levels of phospho-CREB and D2 DR were elevated. Previous studies indicated that exposure to morphine in adulthood enhances the risk of psychiatric disorders in offspring. OCD is one the comorbid disorders with addiction and increases the risk of substance abuse disorder in patients. In this survey, we found that morphine exposure in parents before gestation can encourage obsessive-compulsive behavior in offspring.

μ-Opioid receptor in the CA1 involves in tramadol and morphine cross state-dependent memory

In the present study, the effect of tramadol - an opioid painkiller drug with abuse potential- on amnesia and state-dependent memory and its interaction with the opioidergic system was investigated in male Wistar rats. Intra CA-1 administration of tramadol (0.5, 1, and 2 μg/rat) before training, dose-dependently decreased the learning ability in passive avoidance task. Amnesia induced by pre-train tramadol administration was significantly reversed by pre-test administration of tramadol (1 μg/rat). Pre-test administration of naltrexone (a μ-opioid receptor (MOR) antagonist) inhibited the effect of tramadol on memory retrieval. In addition, the pre-test administration of morphine (1 μg/rat, intra-CA1) also reversed memory impairment induced by pre-train tramadol administration. Although, pre-train morphine administration (1 μg/rat, intra-CA1), induced memory impairment reversed by pre-test tramadol administration (1 μg/rat, intra-CA1). In addition, the level of MOR in the hippocampus decreased in animals with memory impairment due to using tramadol in the training day. However, state-dependent retrieval using tramadol or cross state-dependent retrieval using morphine enhanced the MOR level in the hippocampus. The results of the study suggested that intra-CA1 tramadol administration induced memory impairment, improved by pre-test administration of either tramadol or morphine (MOR agonist). It could be concluded that tramadol is capable to induced state-dependent memory and also, it has a cross state-dependent memory with morphine in the hippocampus, done possibly through MOR.

Morphine Exposure and Enhanced Depression-like Behaviour Confronting Chronic Stress in Adult Male Offspring Rat

Introduction:

Opioid addiction is an important concern in the World. Reports demonstrate that substance use disorder could influence genetic and environmental factors, and children of addicts have a higher rate of psychopathology. In this study, we investigated depression-like behavior among offspring of morphine-exposed rat parents.

Methods:

Adult male and female Wistar rats received morphine for 21 consecutive days and then let them were free of drugs for ten days. Offspring of these rats were divided into three distinct groups: maternal morphine-exposed, paternal morphine-exposed, and both maternal and paternal morphine-exposed. We used sucrose preference and Forced Swim Test (FST) to measure depression-like behavior. Also, we induced chronic mild stress using repeated corticosterone injection and evaluated depression-like behavior in offspring of morphine-exposed parents compared with offspring of healthy ones.

Results:

Results indicated that depression-like behaviors in the offspring of morphine-exposed rats were higher than those in the offspring of the control group in confronting with chronic mild stress. Additionally, mild chronic stress can produce an exaggerated effect on depression-like behavior in offspring of the morphine-exposed parent(s) compared with those of the control group.

Conclusion:

Our data support the previous hypothesis that the depression rate is higher in the children of addicts. We verified that even when mother or father was clean of opioid in the time of gestation, their children would be susceptible to depression. Dysregulation of hypothalamic-pituitary-adrenal axis and changing in neuronal features in the hippocampus increased depression-like behavior in the offspring of morphine-exposure parents.

NMDA receptor subunits change in the prefrontal cortex of pure-opioid and multi-drug abusers: a post-mortem study

Addiction is a chronic relapsing disorder and is one of the most important issues in the world. Changing the level of neurotransmitters and the activities of their receptors, play a major role in the pathophysiology of substance abuse disorders. It is well-established that N-methyl-D-aspartate receptors (NMDARs) play a significant role in the molecular basis of addiction. NMDAR has two obligatory GluN1 and two regionally localized GluN2 subunits. This study investigated changes in the protein level of GluN1, GluN2A, and GluN2B in the prefrontal cortex of drug abusers. The medial prefrontal cortex (mPFC), lateral prefrontal cortex (lPFC), and orbitofrontal cortex (OFC) were dissected from the brain of 101 drug addicts brains and were compared with the brains of non-addicts (N = 13). Western blotting technique was used to show the alteration in NMDAR subunits level. Data obtained using Western blotting technique showed a significant increase in the level of GluN1 and GluN2B, but not in GluN2A subunits in all the three regions (mPFC, lPFC, and OFC) of men whom suffered from addiction as compared to the appropriate controls. These findings showed a novel role for GluN1, GluN2B subunits, rather than the GluN2A subunit of NMDARs, in the pathophysiology of addiction and suggested their role in the drug-induced plasticity of NMDARs.

Tramadol induces changes in Δ-FosB, µ-opioid receptor, and p-CREB level in the nucleus accumbens and prefrontal cortex of male Wistar rat

BACKGROUND

Besides the analgesic effect of tramadol, prolonged exposure to tramadol can induce adaptive changes thereby leading to dependence and tolerance. Tramadol induces its effect via µ-opioid receptor (MOR). However, tramadol has other targets such as serotonin and epinephrine transporters.

OBJECTIVE

CREB and ΔFosB are transcriptional factors, which are involved in the behavioral abnormalities underlying drug abuse. In this study, the effects of acute and chronic tramadol treatments on MOR, ΔFosB, and CREB levels were studied.

METHODS

For this purpose, 36 male Wistar rats were used. The animals were divided into two main groups. A total of 18 animals received tramadol (0, 5, and 10 mg/kg) acutely and 18 animals received the same doses for the following 14 days. One hour after the last injection, the NAC and PFC were dissected and kept at -80°C in liquid nitrogen. Using western blotting technique, the levels of MOR, ΔFosB, and p-CREB were evaluated.

RESULTS

In the NAC, acute tramadol exposure increases the levels of MOR and p-CREB. Moreover, chronic tramadol administration in this region results in elevated levels of MOR, ΔFosB and p-CREB compared with saline-treated rats. The levels of MOR and p-CREB in the PFC increased in both acute and chronic tramadol exposure. Also, ΔFosB levels increased only following chronic tramadol administration. The results revealed that adaptive changes occurred during drug exposure.

CONCLUSION

We concluded that both CREB and ΔFosB played a role in tramadol dependence. Additionally, increased MOR levels during tramadol treatments might be due to receptor desensitization.

Benefit effect of REM-sleep deprivation on memory impairment induced by intensive exercise in male wistar rats: with respect to hippocampal BDNF and TrkB

BACKGROUND

Many factors affect our learning and memory quality, but according to different studies, having a positive or negative impact pertains to their characteristics like intensity or the amount.

PURPOSE

The present study was conducted to investigate the effect of 24-hour REM-sleep deprivation on continuous-high intensity forced exercise-induced memory impairment and its effect on Brain-Derived Neurotrophic Factor (BDNF) and Tyrosine kinase B (TrkB) levels in the hippocampus and Prefrontal Cortex area (PFC).

MATERIAL AND METHODS

Animals were conditioned to run on treadmills for 5 weeks then, were deprived of sleep for 24 h using the modified multiple platforms. The effect of intensive exercise and/or 24-h REM-SD was studied on behavioral performance using Morris Water Maze protocol for 2 days, and BDNF/TrkB levels were assessed in hippocampus and PFC after behavioral probe test using western blotting.

RESULTS

After 5 weeks of intensive exercise and 24-h REM-SD, spatial memory impairment and reduction of BDNF and TrkB levels were found in hippocampus and PFC. 24-h REM-SD improved memory impairment and intensive exercise-induced downregulation of BDNF and TrkB protein levels.

CONCLUSION

The results of the study suggested that sleep deprivation might act as a compensatory factor to reduce memory impairment when the animal is under severe stressful condition.

NMDA receptors of blood lymphocytes anticipate cognitive performance variations in healthy volunteers

Working memory (WM) system, temporarily stores information and uses this information for complex cognitive tasks. WM connects memory, emotional feelings and perception. Evidence compelling that N-methyl d-aspartate receptor (NMDAR) expression relatively affect WM performance in animal models. It has been suggested some peripheral blood lymphocyte's (PBL) receptors are similar with neuronal receptors in the brain, so we measured PBL's receptors changes as a marker of the neuronal receptor. In this study, we examined one hundred adult men with Wisconsin Card Sorting Test (WCST) as a tool for primary screening for executive function (EF) which include WM. Then, we selected fifty individuals with high and low WCST scores. With digit span and symmetry span tasks, we screened 20 samples for high WM group and 19 samples for low WM group. After separating PBL, we measured mRNA expression level changes in NMDAR subunits with Reverse transcription-polymerase chain reaction method. We demonstrated that GluN2D increased and GluN3A decreased in individuals with high WM compared with the low WM (P < .01 and P < .001, respectively). The expression levels of GluN2A, GluN2B, and GluN3B were not altered between two groups (P > .05). Modifying the PBL receptors could be future approaches to defend memory loss and concentrate the senses over WM-related processes in physiological and pathological statuses. We hypothesized that increasing in GluN2 subunits and decreasing in GluN3 subunits led to improving current via NMDAR and subsequently affect WM.

Cocaine- and amphetamine-regulated transcript (CART): A multifaceted neuropeptide

Over the last 35 years, the continuous discovery of novel neuropeptides has been the key to the better understanding of how the central nervous system has integrated with neuronal signals and behavioral responses. Cocaine and amphetamine-regulated transcript (CART) was discovered in 1995 in the rat striatum but later was found to be highly expressed in the hypothalamus. The widespread distribution of CART peptide in the brain complicated the understanding of the role played by this neurotransmitter. The main objective of the current compact review is to piece together the fragments of available information about origin, expression, distribution, projection, and function of CART peptides. Accumulative evidence suggests CART as a neurotransmitter and neuroprotective agent that is mainly involved in regulation of feeding, addiction, stress, anxiety, innate fear, neurological disease, neuropathic pain, depression, osteoporosis, insulin secretion, learning, memory, reproduction, vision, sleep, thirst and body temperature. In spite of the vast number of studies about the CART, the overall pictures about the CART functions are sketchy. First, there is a lack of information about cloned receptor, specific agonist and antagonist. Second, CART peptides are detected in discrete sets of neurons that can modulate countless activities and third; CART peptides exist in several fragments due to post-translational processing. For these reasons the overall picture about the CART peptides are sketchy and confounding.

Morphine exposure before conception affects anxiety-like behavior and CRF level (in the CSF and plasma) in the adult male offspring

It has been proven that exposure to some drugs even before gestation had transgenerational effects. To investigate the changes which induced by parental morphine exposure before gestation; mainly the anxiety-like behavior, Corticotropin Releasing Factor (CRF) level in the CSF and plasma, CRF Receptor 1 (CRFR1), and the level of protein kinase C (PKC-α) were evaluated in the male offspring. Male and female Wistar rats were exposed to morphine for 21 following days. Ten days after last drug exposure, animals were prepared for mating in 4 distinct groups as follow: drug-naïve female and male (used as control), drug-naïve female and morphine-abstinent male, drug-naïve male and morphine-abstinent female, and morphine abstinent male and female. Offspring were subjected to assess anxiety-like behavior (using elevated plus maze test). CSF and plasma were gathered, and the CRF level was evaluated by ELISA. Using real-time PCR, the CRFR1 level in the brain was evaluated. Results showed that anxiety-like behavior increased in the offspring of morphine-abstinent parent(s) compared with the control group. CRF level in the plasma and CSF also increased in the litter of morphine-abstinent parent(s). CRFR1 mRNA level was upregulated in the brain of offspring with one and/or two morphine-abstinent parent(s). Furthermore, the level of PKC-α was decreased in the brain of offspring which had one and/or two morphine-abstinent parent(s). Taken together, our findings indicated that morphine exposure even before gestation induced transgenerational effects via dysregulation of HPA axis which results in anxiety in the adult male offspring.

Influence of citicoline on citalopram-induced antidepressant activity in depressive-like symptoms in male mice

Depression is associated with significant functional disabilities. Application of new drugs which could enhance the effectiveness of antidepressants drug and reduce side effects of their long-term use seems necessary. Citicoline is used as an effective chemical agent for improving the symptoms of some neurodegenerative diseases. Therefore, in this survey, the application of citicoline as an adjuvant drug was evaluated in mice model of depression. A total of 180 adult NMRI male albino mice were used in this study. All groups were exposed to chronic unexpected mild stress (CUMS) followed by treatment with various doses of citalopram or/and citicoline or saline for 21 days. Sucrose preference (SP), open field (OF), and forced swimming test (FST) were applied to evaluate depression symptoms in the groups. The results indicated that only citicoline at the 5 mg/kg dose had shifted its status from being noneffective to become significantly effective in the co-administered group. The means of SP, OFT, and FST of the treatment groups were significantly different in favor of co-administered group compared with the other groups as well as the control group. Based on the results, it can be concluded that administration of citicoline, as an adjuvant drug, in combination with citalopram, enhanced the effectiveness of selective serotonin reuptake inhibitors (SSRI) drugs for depression treatment.

Expression of NMDA receptor subunits in human blood lymphocytes: A peripheral biomarker in online computer game addiction

Background and aims Repeated performance of some behaviors such as playing computer games could result in addiction. The NMDA receptor is critically involved in the development of behavioral and drug addictions. It has been claimed that the expression level of neurotransmitter receptors in the brain may be reflected in peripheral blood lymphocytes (PBLs). Methods Here, using a real-time PCR method, we have investigated the mRNA expression of GluN2A, GluN2D, GluN3A, and GluN3B subunits of the NMDA receptor in PBLs of male online computer game addicts (n = 25) in comparison with normal subjects (n = 26). Results Expression levels of GluN2A, GluN2D, and GluN3B subunits were not statistically different between game addicts and the control group. However, the mRNA expression of the GluN3A subunit was downregulated in PBLs of game addicts. Discussion and conclusions Transcriptional levels of GluN2A and GluN2D subunits in online computer game addicts are similar to our previously reported data of opioid addiction and are not different from the control group. However, unlike our earlier finding of drug addiction, the mRNA expression levels of GluN3A and GluN3B subunits in PBLs of game addicts are reduced and unchanged, respectively, compared with control subjects. It seems that the downregulated state of the GluN3A subunit of NMDA receptor in online computer game addicts is a finding that deserves more studies in the future to see whether it can serve as a peripheral biomarker in addiction studies, where the researcher wants to rule out the confusing effects of abused drugs.

Is the Nociception Mechanism Altered in Offspring of Morphine-Abstinent Rats?

To investigate the effect of parental drug abuse on children, nociception, electrophysiological alteration, mRNA expression of opioid receptors, and expression of certain intracellular proteins in offspring of morphine-abstinent rats were studied. Adult male and female animals received water-soluble morphine for 21 days. Ten days after the last morphine administration, animals were placed for mating in 4 groups as follows: healthy (drug naive) female and male, morphine-abstinent female and healthy male, morphine-abstinent male and healthy female, morphine-abstinent male and morphine-abstinent female. Their adult male offspring were tested for nociception, neuronal discharge in nucleus accumbens (NAC) and prefrontal cortex (PFC). Our results showed that nociception in male offspring of all morphine-abstinent parent(s) groups was significantly reduced, compared with the control group. In the offspring of morphine-abstinent parent(s) groups, sensitivity to the antinociceptive effect of morphine was enhanced in chronic as well as in acute phases of the formalin test. Neuronal electrical activity reduced in the offspring of the morphine-exposed parent(s) in NAC as well as PFC regions. Moreover, our findings show that opioid receptors' expressions (µ, κ, and δ) increased in NAC of the litter of morphine-abstinent parent(s), compared with the control group. In addition, the expression of κ receptors was remarkably increased in the PFC in morphine-abstinent parent group, relative to the control group. The phosphorylated levels of extracellular regulated kinase 1/2 and cyclic adenosine monophosphate responsive element binding protein were significantly higher in the offspring of the morphine-abstinent parent(s) than the control group in the NAC. Our results indicated that endogenous opioid is altered in offspring of the morphine-exposed parent(s) and that heritage has a major role.

PERSPECTIVE

This study showed that nociception was reduced in offspring of morphine-abstinent rat(s) and also these litters had a low level of neuronal firing rate, and enhanced opioid receptors expression, especially in the NAC. Because these offspring are more sensitive to the analgesic effect of morphine, clinicians should consider this issue to manage the dosage of morphine for treating pain in children with an abstinent parent(s).

Anxiolytic-like effect induced by the cannabinoid CB1 receptor agonist, arachydonilcyclopropylamide (ACPA), in the rat amygdala is mediated through the D1 and D2 dopaminergic systems

In the present study the influence of the dopaminergic system(s) of the amygdala on the anxiolytic-like effect of the cannabinoid CB1 receptor agonist, arachydonilcyclopropylamide (ACPA), in male Wistar rats was investigated. An elevated plus-maze test of anxiety was used to assess anxiety-like behaviors. The results showed that bilateral intra-amygdala injections of ACPA (0.125, 1.25 and 5 ng/rat) and the mixed dopamine D1/D2 receptor agonist, apomorphine, at different doses (0.001, 0.01 and 0.1 µg/rat) increased percentage open arm time (%OAT) and percentage open arm entries (%OAE), indicating an anxiolytic-like effect for both of the drugs. In contrast, intra-amygdala administration of the dopamine D1 receptor antagonist SCH23390 (0.5 and 1 µg/rat) and the dopamine D2 receptor antagonist, sulpiride (2 and 3 µg/rat) decreased %OAT and %OAE, suggesting an anxiogenic-like effect for both of the drugs. Interestingly, pretreatment with a sub-effective dose of apomorphine (0.0005 µg/rat) increased, while SCH23390 (0.25 µg/rat) and sulpiride (1.5 µg/rat) decreased the anxiolytic-like effect of ACPA. It can be concluded that the dopaminergic system of the amygdala may be involved, at least partly, in the anxiolytic-like effects induced by ACPA in the rat amygdala.