Increased attention has focused on methods to increase empathy, compassion, and pro-social behavior. Meditation practices have traditionally been used to cultivate pro-social outcomes, and recently investigations have sought to evaluate their efficacy for these outcomes. We conducted a systematic review and meta-analysis of meditation for pro-social emotions and behavior. A literature search was conducted in PubMed, MEDLINE, PsycINFO, CINAHL, Embase, and Cochrane databases (inception-April 2016) using the search terms: mindfulness, meditation, mind-body therapies, tai chi, yoga, MBSR, MBCT, empathy, compassion, love, altruism, sympathy, or kindness. Randomized controlled trials in any population were included (26 studies with 1,714 subjects). Most were conducted among healthy adults (=11) using compassion or loving kindness meditation (=18) over 8-12weeks (=12) in a group format (=17). Most control groups were wait-list or no-treatment (=15). Outcome measures included self-reported emotions (e.g., composite scores, validated measures) and observed behavioral outcomes (e.g., helping behavior in real-world and simulated settings). Many studies showed a low risk of bias. Results demonstrated small to medium effects of meditation on self-reported (SMD = .40, < .001) and observable outcomes (SMD = .45, < .001) and suggest psychosocial and neurophysiological mechanisms of action. Subgroup analyses also supported small to medium effects of meditation even when compared to active control groups. Clinicians and meditation teachers should be aware that meditation can improve positive pro-social emotions and behaviors.

Benzodiazepines are prescribed widely but their utility is limited by unwanted side effects, including abuse potential. The mechanisms underlying the abuse-related effects of benzodiazepines are not well understood, although a1 subunit-containing GABA A receptors have been proposed to have a critical role. Here, we examine the reinforcing effects of several compounds that vary with respect to intrinsic efficacy at a2, a3, and a5 subunit-containing GABA A receptors but lack efficacy at a1 subunit-containing GABA A receptors ('a1-sparing compounds'): MRK-623 (functional selectivity for a2/a3 subunit-containing receptors), TPA023B (functional selectivity for a2/a3/a5 subunit-containing receptors), and TP003 (functional selectivity for a3 subunit-containing receptors). The reinforcing effects of the a1-sparing compounds were compared with those of the non-selective benzodiazepine receptor partial agonist MRK-696, and non-selective benzodiazepine receptor full agonists, midazolam and lorazepam, in rhesus monkeys trained to self-administer midazolam or cocaine, under a progressive-ratio schedule of intravenous (i.v.) drug injection. The a1-sparing compounds were self-administered significantly above vehicle levels in monkeys maintained under a midazolam baseline, but not under a cocaine baseline over the dose ranges tested. Importantly, TP003 had significant reinforcing effects, albeit at lower levels of self-administration than non-selective benzodiazepine receptor agonists. Together, these results suggest that a1 subunit-containing GABA A receptors may have a role in the reinforcing effects of benzodiazepine-type compounds in monkeys with a history of stimulant self-administration, whereas a3 subunit-containing GABA A receptors may be important mediators of the reinforcing effects of benzodiazepine-type compounds in animals with a history of sedative-anxiolytic/benzodiazepine self-administration.

Selective serotonin re-uptake inhibitors (SSRIs), which are used commonly to treat anxiety disorders, have characteristic anxiogenic effects following acute administration. Treatment with anxiolytic benzodiazepines (BZs) may reduce these effects, although little is known about potential drug interactions. Our study evaluated acute anxiogenic–like effects of SSRIs, alone and combined with a BZ. Adult male BALB/c mice received fluoxetine (3.0–30.0 mg/kg, i.p.) or citalopram (3.0–30.0 mg/kg, i.p.) alone or in combination with diazepam (0.3–10.0 mg/kg, i.p.), after which they were evaluated with the light/dark and open-field tests for anxiogenesis/anxiolysis. In addition, release of the stress hormone corticosterone was assessed following combined SSRI/BZ administration. In the light/dark and open-field tests, acute SSRIs produced a behavioral profile consistent with anxiogenesis, while diazepam produced an anxiolytic-like profile. Pre-treatment with diazepam (0.3–10 mg/kg) reversed the effects of an anxiogenic-like dose of an SSRI (18 mg/kg fluoxetine, 30 mg/kg citalopram) in both light/dark and open-field tests. Diazepam, fluoxetine or citalopram, and their combination all significantly increased plasma corticosterone levels to the same degree. These findings suggest that a BZ-type drug can attenuate acute anxiogenic-like effects of an SSRI via a mechanism independent of corticosterone regulation.

Benzodiazepines (BZs) are safe drugs for treating anxiety, sleep, and seizure disorders, but their use also results in unwanted effects including memory impairment, abuse, and dependence. The present study aimed to reveal the molecular mechanisms that may contribute to the effects of BZs in the hippocampus (HIP), an area involved in drug-related plasticity, by investigating the regulation of immediate early genes following BZ administration. Previous studies have demonstrated that both brain derived neurotrophic factor (BDNF) and c-Fos contribute to memory- and abuse-related processes that occur within the HIP, and their expression is altered in response to BZ exposure. In the current study, mice received acute or repeated administration of BZs and HIP tissue was analyzed for alterations in BDNF and c-Fos expression. Although no significant changes in BDNF or c-Fos were observed in response to twice-daily intraperitoneal (i.p.) injections of diazepam (10 mg/kg + 5 mg/kg) or zolpidem (ZP; 2.5 mg/kg + 2.5 mg/kg), acute i.p. administration of both triazolam (0.03 mg/kg) and ZP (1.0 mg/kg) decreased BDNF protein levels within the HIP relative to vehicle, without any effect on c-Fos. ZP specifically reduced exon IV-containing BDNF transcripts with a concomitant increase in the association of methyl-CpG binding protein 2 (MeCP2) with BDNF promoter IV, suggesting that MeCP2 activity at this promoter may represent a ZP-specific mechanism for reducing BDNF expression. ZP also increased the association of phosphorylated cAMP response element binding protein (pCREB) with BDNF promoter I. Future work should examine the interaction between ZP and DNA as the cause for altered gene expression in the HIP, given that BZs can enter the nucleus and intercalate into DNA directly.

Background The behavioral consequences associated with addiction are thought to arise from drug-induced neuroadaptation. The mesolimbic system plays an important initial role in this process, and while the dopaminergic system specifically has been strongly interrogated, a complete understanding of the broad transcriptomic effects associated with cocaine use remains elusive. Methods Using next generation sequencing approaches, we performed a comprehensive evaluation of gene expression differences in the ventral tegmental area and nucleus accumbens of rhesus macaques that had self-administered cocaine for roughly 100 days and saline-yoked controls. During self-administration, the monkeys increased daily consumption of cocaine until almost the maximum number of injections were taken within the first 15 min of the one hour session for a total intake of 3 mg/kg/day. Results We confirm the centrality of dopaminergic differences in the ventral tegmental area, but in the nucleus accumbens we see the strongest evidence for an inflammatory response and large scale chromatin remodeling. Conclusions These findings suggest an expanded understanding of the pathology of cocaine addiction with the potential to lead to the development of alternative treatment strategies.

Although the recreational drug 3,4-methylenedioxymethamphetamine (MDMA) is often described as a selective serotonergic neurotoxin, some research has challenged this view. The objective of this study was to determine the influence of MDMA on subsequent levels of two different markers of dopaminergic function, the dopamine transporter (DAT) as well as dopamine and its major metabolites. In experiment I, adult male Sprague–Dawley rats were administered either a low or moderate dose MDMA binge (2.5 or 5.0 mg/kg × 4 with an inter-dose interval of 1 h) or saline, and were killed 1 week later. The moderate dose dramatically reduced [3H]WIN 35,428 binding to striatal DAT by 73.7% (P ≤ 0.001). In experiment II, animals were binged with a higher dose of MDMA (10 mg/kg × 4) to determine the drug’s effects on concentrations of serotonin (5-HT), dopamine, and their respective major metabolites 5-hydroxyindoleacetic acid (5-HIAA), dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in the striatum and frontal cortex 1 week later. As expected, MDMA significantly reduced 5-HT and 5-HIAA (≥ 50%) in these structures, while only a marginal decrease in dopamine was noted in the striatum. In contrast, levels of DOPAC (34.3%, P < 0.01) and HVA (33.5%, P < 0.001) were reduced by MDMA treatment, suggesting a decrease in dopamine turnover. Overall, these findings indicate that while serotonergic markers are particularly vulnerable to MDMA-induced depletion, significant dopaminergic deficits may also occur under some conditions. Importantly, DAT expression may be more vulnerable to perturbation by MDMA than dopamine itself.

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