Tobacco smoke and ethanol during adolescence: Both combined- and single-drug exposures lead to short- and long-term disruption of the serotonergic system in the mouse brain

Ganshuang granule plays a pharmacological role in anti-alcoholic and anti-hangover via regulating alcohol metabolism and affecting neurotransmitters

BACKGROUND

To explore the effect of Ganshuang granule on anti-alcoholic and anti-hangover and its potential mechanism.

METHODS

SPF SD rats' drunken model and SPF Kunming mice's hangover model were used as models.

RESULTS

Ganshuang granule could significantly reduce sleep time, the time to climb in mice, and significantly prolong the tolerance time and shorten sleep time in rats (p < 0.05). The blood ethanol concentration of rats in each administration group was lower than that in the model group at each time point (p < 0.05). Compared with the control group, the activities of ADH and ALDH in the liver of the model group were significantly decreased (p < 0.05); the content of DA and 5-HT in the striatum of the model group was significantly increased (p < 0.05); and the activity of AchE in the hippocampus was significantly decreased (p < 0.05). The above processes could be improved and regulated in the drug administration group. Compared with the control group, there was no significant difference between ADH and ALDH in the serum of the model group (p > 0.05). However, the activities of ADH and ALDH in the liver of drunk rats could be upregulated by Ganshuang granule (p < 0.05).

CONCLUSION

Ganshuang granule has the pharmacological effects of anti-alcoholic and anti-hangover, which is related to regulating the activities of ADH and ALDH in the liver, the contents of DA and 5-HT in striatum, and the activity of AchE in the hippocampus.

Adolescent alcohol and nicotine exposure alters the adult response to alcohol use

Adolescence through young adulthood is a unique period of neuronal development and maturation. Numerous agents can alter this process, resulting in long-term neurological and biological consequences. In the clinical literature, it is frequently reported that adolescent alcohol consumption increases the propensity to develop addictions, including alcohol use disorder (AUD), during adulthood. A general limitation of both clinical and human pre-clinical adolescent alcohol research is the high rate of co-using/abusing more than one drug during adolescence, such as co-using/abusing alcohol with nicotine. A primary goal of basic research is elucidating neuroadaptations produced by adolescent alcohol exposure/consumption that promote alcohol and other drug self-administration in adulthood. The long-term goal is to develop pharmacotherapeutics for the prevention or amelioration of these neuroadaptations. This review will focus on studies that have examined the effects of adolescent alcohol and nicotine exposure on adult alcohol consumption, the hypersensitivity of the mesolimbic dopaminergic system, and enhanced responses not only to alcohol but also to nicotine during adulthood. Again, the long-term goal is to identify potential cholinergic agents to prevent or ameliorate the consequences of, peri-adolescent alcohol abuse.

(m-CF3-PhSe)2 benefits against anxiety-like phenotype associated with synaptic plasticity impairment and NMDAR-mediated neurotoxicity in young mice exposed to a lifestyle model

Lifestyle habits including energy-dense foods and ethanol intake are associated with anxiety disorders. m-Trifluoromethyl-diphenyl diselenide [(m-CF₃-PhSe)₂] has been reported to modulate serotonergic and opioidergic systems and elicit an anxiolytic-like phenotype in animal models. This study investigated if the modulation of synaptic plasticity and NMDAR-mediated neurotoxicity contributes to the (m-CF₃-PhSe)₂ anxiolytic-like effect in young mice exposed to a lifestyle model. Swiss male mice (25-days old) were subjected to a lifestyle model, an energy-dense diet (20:20% lard: corn syrup) from the postnatal day (PND) 25-66 and sporadic ethanol (2 g/kg) (3 x a week, intragastrically, i.g.) from PND 45 to 60. From PND 60 to 66, mice received (m-CF₃-PhSe)₂ (5 mg/kg/day; i.g). The corresponding vehicle (control) groups were carried out. After, mice performed anxiety-like behavioral tests. Mice exposed only to an energy-dense diet or sporadic ethanol did not show an anxiety-like phenotype. (m-CF₃-PhSe)₂ abolished the anxiety-like phenotype in young mice exposed to a lifestyle model. Anxious-like mice showed increased levels of cerebral cortical NMDAR2A and 2B, NLRP3 and inflammatory markers, and decreased contents of synaptophysin, PSD95, and TRκB/BDNF/CREB signaling. (m-CF₃-PhSe)₂ reversed cerebral cortical neurotoxicity, the increased levels of NMDA2A and 2B, and decreased levels of synaptic plasticity-related signaling in the cerebral cortex of young mice exposed to a lifestyle model. In conclusion, the (m-CF₃-PhSe)₂ anxiolytic-like effect was associated with the modulation of NMDAR-mediated neurotoxicity and synaptic plasticity in the cerebral cortex of young mice exposed to the lifestyle model.

Conservation of mechanisms regulating emotional-like responses on spontaneous nicotine withdrawal in zebrafish and mammals

BACKGROUND

Nicotine withdrawal syndrome is a major clinical problem. Animal models with sufficient predictive validity to support translation of pre-clinical findings to clinical research are lacking.

AIMS

We evaluated the behavioural and neurochemical alterations in zebrafish induced by short- and long-term nicotine withdrawal.

METHODS

Zebrafish were exposed to 1 mg/L nicotine for 2 weeks. Dependence was determined using behavioural analysis following mecamylamine-induced withdrawal, and brain nicotinic receptor binding studies. Separate groups of nicotine-exposed and control fish were assessed for anxiety-like behaviours, anhedonia and memory deficits following 2-60 days spontaneous withdrawal. Gene expression analysis using whole brain samples from nicotine-treated and control fish was performed at 7 and 60 days after the last drug exposure. Tyrosine hydroxylase (TH) immunoreactivity in pretectum was also analysed.

RESULTS

Mecamylamine-precipitated withdrawal nicotine-exposed fish showed increased anxiety-like behaviour as evidenced by increased freezing and decreased exploration. ³H-Epibatidine labeled heteromeric nicotinic acethylcholine receptors (nAChR) significantly increased after 2 weeks of nicotine exposure while ¹²⁵I-αBungarotoxin labeled homomeric nAChR remained unchanged. Spontaneous nicotine withdrawal elicited anxiety-like behaviour (increased bottom dwelling), reduced motivation in terms of no preference for the enriched side in a place preference test starting from Day 7 after withdrawal and a progressive decrease of memory attention (lowering discrimination index). Behavioural differences were associated with brain gene expression changes: nicotine withdrawn animals showed decreased expression of chrna 4 and chrna7 after 60 days, and of htr2a from 7 to 60 days.The expression of c-Fos was significantly increased at 7 days. Finally, Tyrosine hydroxylase (TH) immunoreactivity increased in dorsal parvocellular pretectal nucleus, but not in periventricular nucleus of posterior tuberculum nor in optic tectum, at 60 days after withdrawal.

CONCLUSIONS

Our findings show that nicotine withdrawal induced anxiety-like behaviour, cognitive alterations, gene expression changes and increase in pretectal TH expression, similar to those observed in humans and rodent models.

Exposure to varenicline protects against locomotor alteration in a MPTP mouse model of Parkinson's disease

The beneficial effects of drugs that act via nicotinic acetylcholine receptors (nAChRs) on Parkinson's disease (PD) symptomatology may explain the negative correlation between cigarette smoking and risk of this neurological condition. Varenicline, an α4β2 nAChR partial agonist approved for smoking cessation treatments, could be valuable for PD treatment. Here, we investigated varenicline effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) PD mouse model. From postnatal day (PN) 90 to PN119, male C57BL/6 mice were exposed daily to varenicline (2 mg/kg) by gavage. After that, MPTP was injected (30 mg/kg, ip) once a day for five days. At PN125, locomotor and anxiety-like effects were assessed with the open field test. At PN126, immobile behavior was assessed with the forced swimming test. At PN127, the frontal cerebral cortex was collected to evaluate dopamine and DOPAC levels. To verify whether varenicline was protective during the MPTP insult, a separate group of MPTP animals received varenicline from PN90 to PN124. MPTP reduced cortical dopamine content and increased dopamine turnover. Those effects were not reversed by varenicline treatment. Interestingly, varenicline reversed the MPTP-induced hyperactivity in the open field. Both maintenance of varenicline treatment during MPTP exposure or its interruption before MPTP exposure elicited similar results. No alterations were observed in anxiety-like behavior or in immobility time. Altogether, these findings suggested that varenicline treatment reduced the MPTP-induced hyperactivity, but did not protect against dopaminergic damage. Based on this partial protective effect, varenicline could exert neuroprotective effects on circuits that control motor activity in PD.

The role of sex in the persistent effects of adolescent alcohol exposure on behavior and neurobiology in rodents

Alcohol drinking is often initiated during adolescence, and this frequently escalates to binge drinking. As adolescence is also a period of dynamic neurodevelopment, preclinical evidence has highlighted that some of the consequences of binge drinking can be long lasting with deficits persisting into adulthood in a variety of cognitive-behavioral tasks. However, while the majority of preclinical work to date has been performed in male rodents, the rapid increase in binge drinking in adolescent female humans has re-emphasized the importance of addressing alcohol effects in the context of sex as a biological variable. Here we review several of the consequences of adolescent ethanol exposure in light of sex as a critical biological variable. While some alcohol-induced outcomes, such as non-social approach/avoidance behavior and sleep disruption, are generally consistent across sex, others are variable across sex, such as alcohol drinking, sensitivity to ethanol, social anxiety-like behavior, and induction of proinflammatory markers.

Altered mRNA Levels of Stress-Related Peptides in Mouse Hippocampus and Caudate-Putamen in Withdrawal after Long-Term Intermittent Exposure to Tobacco Smoke or Electronic Cigarette Vapour

Nicotine addiction is a severe public health problem. The aim of this study was to investigate the alterations in key neurotransmissions after 60 days of withdrawal from seven weeks of intermittent cigarette smoke, e-cigarette vapours, or an e-cigarette vehicle. In the nicotine withdrawal groups, increased depressive and anxiety/obsessive–compulsive-like behaviours were demonstrated in the tail suspension, sucrose preference and marble burying tests. Cognitive impairments were detected in the spatial object recognition test. A significant increase in Corticotropin-releasing factor (Crf) and Crf1 mRNA levels was observed, specifically after cigarette withdrawal in the caudate-putamen nucleus (CPu). The nociceptin precursor levels were reduced by cigarette (80%) and e-cigarette (50%) withdrawal in the CPu. The delta opioid receptor showed a significant reduction in the hippocampus driven by the exposure to an e-cigarette solubilisation vehicle, while the mRNA levels doubled in the CPu of mice that had been exposed to e-cigarettes. Withdrawal after exposure to e-cigarette vapour induced a 35% Bdnf mRNA decrease in the hippocampus, whereas Bdnf was augmented by 118% by cigarette withdrawal in the CPu. This study shows that long-term withdrawal-induced affective and cognitive symptoms associated to lasting molecular alterations in peptidergic signalling may determine the impaired neuroplasticity in the hippocampal and striatal circuitry.

Sex- and age-dependent differences in nicotine susceptibility evoked by developmental exposure to tobacco smoke and/or ethanol in mice

Either tobacco smoking or alcohol consumption during pregnancy sex-selectively increases susceptibility to drugs of abuse later in life. Considering that pregnant smoking women are frequently intermittent consumers of alcoholic beverages, here, we investigated whether a short-term ethanol exposure restricted to the brain growth spurt period when combined with chronic developmental exposure to tobacco smoke aggravates susceptibility to nicotine in adolescent and adult mice. Swiss male and female mice were exposed to tobacco smoke (SMK; research cigarettes 3R4F, whole-body exposure, 8 h/daily) or ambient air during the gestational period and until the tenth postnatal day (PN). Ethanol (ETOH, 2 g/Kg, 25%, i.p.) or saline was injected in the pups every other day from PN2 to PN10. There were no significant differences in cotinine (nicotine metabolite) and ethanol serum levels among SMK, ETOH and SMK + ETOH groups. During adolescence (PN30) and adulthood (PN90), nicotine (NIC, 0.5 mg/Kg) susceptibility was evaluated in the conditioned place preference and open field tests. NIC impact was more evident in females: SMK, ETOH and SMK + ETOH adolescent females were equally more susceptible to nicotine-induced place preference than control animals. At adulthood, SMK and SMK + ETOH adult females exhibited a nicotine-evoked hyperlocomotor profile in the open field, with a stronger effect in the SMK + ETOH group. Our results indicate that ethanol exposure during the brain growth spurt, when combined to developmental exposure to tobacco smoke, increases nicotine susceptibility with stronger effects in adult females. This result represents a worsened outcome from the early developmental dual exposure and may predispose nicotine use/abuse later in life.

Persistent cognitive and affective alterations at late withdrawal stages after long-term intermittent exposure to tobacco smoke or electronic cigarette vapour: Behavioural changes and their neurochemical correlates

Smoking cessation induces a withdrawal syndrome associated with anxiety, depression, and impaired neurocognitive functions, but much less is known about the withdrawal of e-cigarettes (e-CIG). We investigated in Balb/c mice the behavioural and neurochemical effects of withdrawal for up to 90 days after seven weeks' intermittent exposure to e-CIG vapour or cigarette smoke (CIG). The withdrawal of e-CIG and CIG induced early behavioural alterations such as spatial memory deficits (spatial object recognition task), increased anxiety (elevated plus maze test) and compulsive-like behaviour (marble burying test) that persisted for 60-90 days. Notably, attention-related (virtual object recognition task) and depression-like behaviours (tail suspension and sucrose preference tests) appeared only 15-30 days after withdrawal and persisted for as long as up to 90 days. At hippocampal level, the withdrawal-induced changes in the levels of AMPA receptor GluA1 and GluA2/3 subunits, PSD 95 protein, corticotropin-releasing factor (Crf) and Crf receptor 1 (CrfR1) mRNA were biphasic: AMPA receptor subunit and PSD95 protein levels initially remained unchanged and decreased after 60-90 days, whereas Crf/CrfR1 mRNA levels initially increased and then markedly decreased after 60 days. These late reductions correlated with the behavioural impairments, particularly the appearance of depression-like behaviours. Our findings show that major behavioural and neurochemical alterations persist or even first appear late after the withdrawal of chronic CIG smoke or e-CIG vapour exposure, and underline importance of conducting similar studies of humans, including e-CIG vapers.

Adolescent Δ9-Tetrahydrocannabinol Exposure Selectively Impairs Working Memory but Not Several Other mPFC-Mediated Behaviors

As the frequency of cannabis use by 14-16-year-olds increases, it becomes increasingly important to understand the effect of cannabis on the developing central nervous system. Using mice as a model system, we treated adolescent (28 day old) C57BL6/J mice of both sexes for 3 weeks with 3 mg/kg tetrahydrocannabinol (THC). Starting a week after the last treatment, several cognitive behaviors were analyzed. Mice treated with THC as adolescents acquired proficiency in a working memory task more slowly than vehicle-treated mice. Working memory recall in both sexes of THC-treated mice was also deficient during increasing cognitive load compared to vehicle-treated mice. Our adolescent THC treatment did not strongly affect social preference, anxiety behaviors, or decision-making behaviors on the elevated T maze task. In summary, under the conditions of this study, adolescent THC treatment of mice markedly affected the establishment, and persistence of working memory, while having little effect on decision-making, social preference or anxiety behaviors. This study provides further support that adolescent THC affects specific behavioral domains.