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.

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.

Beneficial effects of physical activity on depressive and OCD-like behaviors in the male offspring of morphine-abstinent rats.

The role of parental morphine exposure before gestation on mood disorder in the offspring was well described. Besides, physical activity can improve the symptoms of mood disorders. So, the current study aimed to investigate the role of physical activity on depressive and OCD-like behaviors induced by parental morphine exposure. 40 male and 40 female Wistar rats (60-days old) received morphine for consecutive 10 days and were drug-free for 10 days. They were prepared for mating either with a morphine-abstinent or with a drug-naïve rat. The adult male offspring were divided into two groups as follows: (1) those that were subjected to treadmill exercise for three weeks (3-days each week), and (2) those without exercise. Also, the offspring were subjected to forced swimming and marble-burying tests. The levels of 5-HT3 receptor (R), D1, and D2 dopamine receptor (DR) were evaluated as well as the level of monoamine oxidase-B (MAO-B) in the prefrontal cortex (PFC). Results showed that exercise improved depressive and OCD-like behaviors in the offspring of morphine-abstinent rats. Western blotting data revealed that the levels of 5-HT3R, D1DR, D2DR, and MAO-B in the PFC increased in the offspring of morphine-abstinent rats compared to the control. However, it was shown that treadmill exercise decreases the levels of 5-HT3R, MAO-B, and D2DR. Morphine exposure, even before conception, could affect the behaviors in the offspring. Besides, the molecular changes were also detected in the brain. We found that mild physical activity might modulate OCD and depressive-like behavior in the offspring of morphine-abstinent rats by decreasing the levels of 5-HT3R, D2DR, and MAO-B located in the PFC.

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.