Modulatory role of the intra-accumbal CB1 receptor in protein level of the c-fos and pCREB/CREB ratio in the nucleus accumbens and ventral tegmental area in extinction and morphine seeking in the rats

Anxiety and Gene Expression Enhancement in Mice Exposed to Glyphosate-Based Herbicide

Growing evidence demonstrates that serotonin (5-HT) depletion increases activity in the amygdala and medial prefrontal cortex (mPFC), ultimately leading to anxiety behavior. Previously, we showed that glyphosate-based herbicides (GBHs) increased anxiety levels and reduced the number of serotoninergic fibers within the mPFCs and amygdalas of exposed mice. However, the impact of this 5-HT depletion following GBH exposure on neuronal activity in these structures is still unknown. In this study, we investigated the effects of GBH on immediate early gene (IEG) activation within the mPFCs and amygdalas of treated mice from juvenile age to adulthood and its subsequent effects on anxiety levels. Mice were treated for subchronic (6 weeks) and chronic (12 weeks) periods with 250 or 500 mg/kg/day of GBH and subjected to behavioral testing using the open field and elevated plus maze paradigms. Then, we analyzed the expression levels of c-Fos and pCREB and established the molecular proxies of neuronal activation within the mPFC and the amygdala. Our data revealed that repeated exposure to GBH triggers anxiogenic behavior in exposed mice. Confocal microscopy investigations into the prelimbic/infralimbic regions of the mPFC and in basolateral/central nuclei of the amygdala disclosed that the behavioral alterations are paralleled by a robust increase in the density and labelling intensity of c-Fos- and pCREB-positive cells. Taken together, these data show that mice exposed to GBH display the hyperactivation of the mPFC–amygdala areas, suggesting that this is a potential mechanism underlying the anxiety-like phenotype.

Smoke, nicotine, opioids, and cannabinoids effects on the ACE2 protein level and possibility of COVID-19 infection: Suggesting potential preventives and therapeutics

Introduction. The coronavirus caused the pandemic COVID-19 that has an extensive influence in the world. The virus enters and infects body cells through superficial protein ACE2. Each cell possessing ACE2 is potentially vulnerable to this virus. Since the respiratory system is exposed to the environment and has ACE2, it is one of the first candidates infected by the virus. One of the considerable complications in the severe stage of COVID-19 is an intense adaptive immunological response that is detrimental to body organs. Methods. This is a review article. All relevant articles which were accessible were reviewed. Results. Some drugs of abuse may have an adverse or beneficial influence on the disease, and their simultaneity with COVID-19 is remarkable. Nicotine and cholinergic nicotinic receptor agonists seem to decrease the cell's membrane superficial ACE2 protein number; thus, they would be appropriate candidates for COVID-19 prevention and expansion. Both opioids and cannabinoids attenuate the immune system and seem to be adverse for disease incidence but can be beneficial for the severe stage of COVID19. The antitussive effect of some opioids would be advantageous. Furthermore, some opioids are substrates for ACE2 and they bind it. Therefore, they would be an appropriate candidate to design a drug covering ACE2 with a high affinity to prevent coronavirus infection. Conclusion. Some drugs, such as nicotine and opioids, may have beneficial effects on preventing or reducing COVID-19 complications.

Cannabinoid receptor modulation changes the accumbal neuronal responses to morphine in the reinstatement of morphine-induced conditioned place preference

The nucleus accumbens (NAc) is a central component of the brain reward system. It has been known that most of the drugs of abuse such as opioids and cannabinoids affect the NAc. Although cannabinoids can modulate different stages of morphine encounter such as the reinstatement of morphine-induced conditioned place preference (CPP), there is no evidence for the NAc neurons' response to prove it. That is why the present study was designed. The procedure was as follows: The rats were entered to CPP by sc 5 mg/kg morphine in three consecutive days. During the extinction period or in the reinstatement phase, icv WIN 55,212-2 (10mM/5 μL dimethyl sulfoxide [DMSO] 10%) or AM251 (0.5mM/5-μL DMSO 10%) was infused in separate groups. Also, the NAc neurons' response to cannabinoid modulation in reinstatement to morphine was investigated by extracellular single unit recording. As a result, the cannabinoid in the reinstatement phase decreased the NAc neuronal activity. The CB1 receptor inhibition during the extinction period increased the NAc firing rate after ip 1 mg/kg morphine. Also, the inhibition of this receptor in the reinstatement phase increased the NAc neurons' firing rate. The inhibitory effect of cannabinoid on the NAc neuronal activity in the reinstatement has indicated the possible potency of cannabinoid to induce reinstatement of morphine-induced CPP alone and in the absence of a priming dose of morphine. Also, the different effects of the CB1 agonist during the extinction period in the reinstatement phase suggest different mechanisms underlying these two parts.

Effects of Chronic Ephedrine Toxicity on Functional Connections, Cell Apoptosis, and CREB-Related Proteins in the Prefrontal Cortex of Rhesus Monkeys

Ephedrine abuse has spread in many parts of the world, severely threatening human health. The mechanism of ephedrine toxicity is still unclear. To explore the possible neural mechanisms of ephedrine toxicity, this study established a non-human primate model of ephedrine exposure, analyzed the functional connectivity changes in its prefrontal cortex through resting state BOLD-fMRI, and then inspected the pathophysiological changes as well as the expression of the cyclic adenosine monophosphate response element-binding protein (CREB), phosphorylated CREB (P-CREB), and CREB target proteins (c-fos and fosB) in the prefrontal cortex. After ephedrine toxicity, we found that the prefrontal cortex of monkeys strengthened its functional connectivity with the brain regions that perform motivation, drive, reward, and learning and memory functions and weakened its functional connectivity with the brain regions that perform cognitive control. These results suggest that ephedrine toxicity causes abnormal neural circuits that lead to the amplification and enhancement of drug-related cues and the weakening and damage of cognitive control function. Histology showed that the neurocytotoxicity of ephedrine can cause neuronal degeneration and apoptosis. Real-time PCR and Western blot showed increased expression of CREB mRNA and CREB/P-CREB/c-fos/fosB protein in the prefrontal cortex after ephedrine toxicity. Collectively, the present study indicates that the enhancement of drug-related cues and the weakening of cognitive control caused by abnormal neural circuits after drug exposure may be a major mechanism of brain function changes caused by ephedrine. These histological and molecular changes may be the pathophysiological basis of brain function changes caused by ephedrine.

Effect of acute and chronic restraint stress on electrical activity of prefrontal cortex neurons in the reinstatement of extinguished methamphetamine-induced conditioned place preference: An electrophysiological study

Increased vulnerability to drug abuse has been observed after exposure to stress and the prefrontal cortex (PFC) plays a major role in the control of the stress response and reward pathway. The current study was conducted to clarify the effects of acute and chronic restraint stress on PFC neural activity during the reinstatement of methamphetamine (METH)-induced conditioned place preference (CPP) in rats. Following the establishment of CPP (METH 0.5 mg/kg; s.c. for 3 days) and the extinction phase, male Wistar rats were divided into threshold (0.25 mg/kg; s.c.) and sub-threshold (0.125 mg/kg; s.c.) METH-treated super groups to induce reinstatement. Each super group contained control (non-stressed), acute restraint stress (ARS) and chronic restraint stress (CRS) groups. in vivo single unit recordings were performed on the urethane-anesthetized rats in these groups. After baseline recordings (10-min period) of the neurons in the PFC, their firing activity was recorded for 50 min during the reinstatement phase after injection of METH. The results showed that the threshold dose, but not the sub-threshold dose, of METH significantly increased PFC neural activity in the non-stressed animals. The sub-threshold dose of METH notably changed this activity in both the ARS and CRS groups. These changes in the excited neurons after the sub-threshold dose in the ARS and CRS groups were significantly higher than those in the non-stressed group. It appears that the PFC is implicated in the associated reward pathway and stress functions. METH affected the firing rate of PFC neurons and stress amplified the effect of METH on changes in the neuronal firing rate in the PFC.