Sex-dependent differences in the anxiolytic-like effect of cannabidiol in the elevated plus-maze

Neuronal nicotinic acetylcholine receptor of the central amygdala modulates the ethanol-induced tolerance to anxiolysis and withdrawal-induced anxiety in male rats

The nicotine acetylcholinergic receptor (nAchR) in the central nucleus of the amygdala (CeA) is known to modulate anxiety traits as well as ethanol-induced behavioral effects. Therefore, the present study investigated the role of CeA nAChR in the tolerance to ethanol anxiolysis and withdrawal-induced anxiety-related effects in rats on elevated plus maze (EPM). To develop ethanol dependence, rats were given free access to an ethanol-containing liquid diet for 10 days. To assess the development of tolerance, separate groups of rats were challenged with ethanol (2 g/kg, i.p.) on days 1, 3, 5, 7 and 10 during the period of ethanol exposure, followed by an EPM assessment. Moreover, expression of ethanol withdrawal was induced after switching ethanol-dependent rats to a liquid diet on day 11, and withdrawal-induced anxiety-like behavior was noted at different post-withdrawal time points using the EPM test. The ethanol-dependent rats were pretreated with intra-CeA (i.CeA) (bilateral) injections of nicotine (0.25 µg/rat) or mecamylamine (MEC) (5 ng/rat) before the challenge dose of ethanol on subthreshold tolerance on the 5th day or on peak tolerance day, that is, 7th or 10th, and before assessment of postwithdrawal anxiety on the 11th day on EPM. Bilateral i.CeA preadministration of nicotine before the challenge dose of ethanol on days 5, 7 and 10 exhibited enhanced tolerance, while injection of MEC, completely mitigated the tolerance to the ethanol-induced antianxiety effect. On the other hand, ethanol-withdrawn rats pretreated i.CeA with nicotine exacerbated while pretreatment with MEC, alleviated the ethanol withdrawal-induced anxiety on all time points. Thus, the present investigation indicates that stimulation of nAChR in CeA negatively modulates the ethanol-induced chronic behavioral effects on anxiety in rats. It is proposed that nAChR antagonists might be useful in the treatment of alcohol use disorder and ethanol withdrawal-related anxiety-like behavior.

Effects of acute cannabidiol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice

Background

Some evidence suggests that cannabidiol (CBD) has potential to help alleviate HIV symptoms due to its antioxidant and anti-inflammatory properties. Here we examined acute CBD effects on various behaviors and the endocannabinoid system in HIV Tat transgenic mice.

Methods

Tat transgenic mice (female/male) were injected with CBD (3, 10, 30 mg/kg) and assessed for antinociception, activity, coordination, anxiety-like behavior, and recognition memory. Brains were taken to quantify endocannabinoids, cannabinoid receptors, and cannabinoid catabolic enzymes. Additionally, CBD and metabolite 7-hydroxy-CBD were quantified in the plasma and cortex.

Results

Tat decreased supraspinal-related nociception and locomotion. CBD and sex had little to no effects on any of the behavioral measures. For the endocannabinoid system male sex was associated with elevated concentration of the proinflammatory metabolite arachidonic acid in various CNS regions, including the cerebellum that also showed higher FAAH expression levels for Tat(+) males. GPR55 expression levels in the striatum and cerebellum were higher for females compared to males. CBD metabolism was altered by sex and Tat expression.

Conclusion

Findings indicate that acute CBD effects are not altered by HIV Tat, and acute CBD has no to minimal effects on behavior and the endocannabinoid system.

Association between RMTg Neuropeptide Genes and Negative Effect during Alcohol Withdrawal in Mice

Alcohol use disorders (AUDs) frequently co-occur with negative mood disorders, such as anxiety and depression, exacerbating relapse through dopaminergic dysfunction. Stress-related neuropeptides play a crucial role in AUD pathophysiology by modulating dopamine (DA) function. The rostromedial tegmental nucleus (RMTg), which inhibits midbrain dopamine neurons and signals aversion, has been shown to increase ethanol consumption and negative emotional states during abstinence. Despite some stress-related neuropeptides acting through the RMTg to affect addiction behaviors, their specific roles in alcohol-induced contexts remain underexplored. This study utilized an intermittent voluntary drinking model in mice to induce negative effect behavior 24 h into ethanol (EtOH) abstinence (post-EtOH). It examined changes in pro-stress (Pnoc, Oxt, Npy) and anti-stress (Crf, Pomc, Avp, Orx, Pdyn) neuropeptide-coding genes and analyzed their correlations with aversive behaviors. We observed that adult male C57BL/6J mice displayed evident anxiety, anhedonia, and depression-like symptoms at 24 h post-EtOH. The laser-capture microdissection technique, coupled with or without retrograde tracing, was used to harvest total ventral tegmental area (VTA)-projecting neurons or the intact RMTg area. The findings revealed that post-EtOH consistently reduced Pnoc and Orx levels while elevating Crf levels in these neuronal populations. Notably, RMTg Pnoc and Npy levels counteracted ethanol consumption and depression severity, while Crf levels were indicative of the mice's anxiety levels. Together, these results underscore the potential role of stress-related neuropeptides in the RMTg in regulating the negative emotions related to AUDs, offering novel insights for future research.

Antinociceptive action of cannabidiol on thermal sensitivity and post-operative pain in male and female rats

This study investigated the antinociceptive potential of cannabidiol (CBD) in male and female Wistar rats. The assessment and analysis included tail withdrawal to thermal stimulation (tail flick test) and mechanical allodynia induced by plantar incision injury (von Frey test). CBD reduced acute thermal sensitivity in uninjured animals and post-operative mechanical allodynia in males and females. In the tail flick test, CBD 30 mg/kg i.p. was required to induce antinociception in males. During the proestrus phase, females did not show a statistically significant antinociceptive response to CBD treatment despite a noticeable trend. In contrast, in a separate group of rats tested during the late diestrus phase, antinociception varied with CBD dosage and time. In the post-operative pain model, CBD at 3 mg/kg decreased mechanical allodynia in males. Similarly, this dose reduced allodynia in females during proestrus. However, in females during late diestrus, the lower dose of CBD (0.3 mg/kg) reduced mechanical allodynia, although the latency to onset of the effect was slower (90 min). The effectiveness of a 10-fold lower dose of CBD during the late diestrus stage in females suggests that ovarian hormones can influence the action of CBD. While CBD has potential for alleviating pain in humans, personalized dosing regimens may need to be developed to treat pain in women.

Astrocyte Activation in the ACC Contributes to Comorbid Anxiety in Chronic Inflammatory Pain and Involves in The Excitation-Inhibition Imbalance

Neurons within the anterior cingulate cortex (ACC) orchestrate the co-occurrence of chronic pain and anxiety. The ACC hyperactivity plays a crucial role in the emotional impact of neuropathic pain. Astrocyte-mediated neuroinflammatory is responsible for regulating the balance between excitation-inhibition (E/I) in the brain. However, there is limited understanding of the possible contributions of astrocytes in the ACC to comorbidity of anxiety and chronic inflammatory pain. This paper aims to investigate the possible contribution of astrocytes in the ACC to the comorbidity between anxiety and chronic inflammatory pain, as well as their involvement in the E/I imbalance of pyramidal cells. Our results show that CFA rats displayed allodynia and anxiety-like behaviors. The E/I balance in the ACC shifts to excitement in comorbidity of chronic pain and anxiety by western blotting, and electrophysiological recording. Result of RNA-Seq also indicated that E/I imbalance and neuroinflammation of ACC were involved in pain-anxiety comorbidity. Then, positive cells of GFAP but not Iba1 in the contralateral ACC were increased; the mRNA expression of GFAP and its activation-related proinflammatory cytokines (TNF-α, IL-6, and IL-1β) in the contralateral ACC were also elevated. Furthermore, specific chemogenic inhibition of ACC astrocytes reversed comorbid pain and anxiety and suppressed high ACC excitability. Our data suggest that astrocytes participate in comorbid pain and anxiety and excitation-inhibition imbalance in ACC. Inhibition astrocyte activation can reduce anxiety related to pain and restore the imbalance in the ACC. These findings shed light on the involvement of astrocytes in comorbid conditions, offering valuable insights into a potential therapeutic approach for the co-occurrence of chronic pain and anxiety.

Sex and estrous cycle-linked differences in the effect of cannabidiol on panic-like responding in rats and mice

Clinical and preclinical studies point towards anxiolytic actions of cannabidiol (CBD), but its effect in panic disorder has been less explored and few studies consider effects in females. We here compared the effect of CBD on the response of male and female rats and mice to a panicogenic challenge; exposure to low O2 (rats) or high CO2 (mice) paying attention in females to possible effects of estrous cycle phase. Male and female Sprague-Dawley rats and C57BL/6 J mice were exposed to 7% O2 for 5 min (rats) or 20% CO2 (mice) and escape behaviour, which has been associated with panic attacks, was quantified as undirected jumps towards the gas chamber's ceiling. The effect of pretreatment with CBD (1-10 mg kg-1 i.p. in rats or 10-60 mg kg-1 i.p. in mice) was tested. The results showed that low O2 (rats) or high CO2 (mice) evoked escape in both sexes. In female rats the response was estrous cycle-sensitive: females in late diestrus made significantly more jumps than females in proestrus. In female mice escape was not influenced by estrous cycle phase and CBD was panicolytic. In female rats CBD attenuated escape behaviour in late diestrus phase but not in proestrus. In male rats and mice CBD had no effect on escape behaviour. Therefore, CBD is panicolytic in female rats and mice but not in males. In rats the effect is estrous cycle-sensitive: rats were most responsive to CBD in late diestrus. In mice higher doses were required to elicit effects and estrous cycle had no effect.

Anti-oxidant effects of cannabidiol relevant to intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a subtype of stroke with a high mortality rate. Oxidative stress cascades play an important role in brain injury after ICH. Cannabidiol, a major non-psychotropic phytocannabinoids, has drawn increasing interest in recent years as a potential therapeutic intervention for various neuropsychiatric disorders. Here we provide a comprehensive review of the potential therapeutic effects of cannabidiol in countering oxidative stress resulting from ICH. The review elaborates on the various sources of oxidative stress post-ICH, including mitochondrial dysfunction, excitotoxicity, iron toxicity, inflammation, and also highlights cannabidiol's ability to inhibit ROS/RNS generation from these sources. The article also delves into cannabidiol's role in promoting ROS/RNS scavenging through the Nrf2/ARE pathway, detailing both extranuclear and intranuclear regulatory mechanisms. Overall, the review underscores cannabidiol's promising antioxidant effects in the context of ICH and suggests its potential as a therapeutic option.

The therapeutic potential of purified cannabidiol

The use of cannabidiol (CBD) for therapeutic purposes is receiving considerable attention, with speculation that CBD can be useful in a wide range of conditions. Only one product, a purified form of plant-derived CBD in solution (Epidiolex), is approved for the treatment of seizures in patients with Lennox-Gastaut syndrome, Dravet syndrome, or tuberous sclerosis complex. Appraisal of the therapeutic evidence base for CBD is complicated by the fact that CBD products sometimes have additional phytochemicals (like tetrahydrocannabinol (THC)) present, which can make the identification of the active pharmaceutical ingredient (API) in positive studies difficult. The aim of the present review is to critically review clinical studies using purified CBD products only, in order to establish the upcoming indications for which purified CBD might be beneficial. The areas in which there is the most clinical evidence to support the use of CBD are in the treatment of anxiety (positive data in 7 uncontrolled studies and 17 randomised controlled trials (RCTs)), psychosis and schizophrenia (positive data in 1 uncontrolled study and 8 RCTs), PTSD (positive data in 2 uncontrolled studies and 4 RCTs) and substance abuse (positive data in 2 uncontrolled studies and 3 RCTs). Seven uncontrolled studies support the use of CBD to improve sleep quality, but this has only been verified in one small RCT. Limited evidence supports the use of CBD for the treatment of Parkinson's (3 positive uncontrolled studies and 2 positive RCTs), autism (3 positive RCTs), smoking cessation (2 positive RCTs), graft-versus-host disease and intestinal permeability (1 positive RCT each). Current RCT evidence does not support the use of purified oral CBD in pain (at least as an acute analgesic) or for the treatment of COVID symptoms, cancer, Huntington's or type 2 diabetes. In conclusion, published clinical evidence does support the use of purified CBD in multiple indications beyond epilepsy. However, the evidence base is limited by the number of trials only investigating the acute effects of CBD, testing CBD in healthy volunteers, or in very small patient numbers. Large confirmatory phase 3 trials are required in all indications.

Therapeutics for Substance-Using Women: The Need to Elucidate Sex-Specific Targets for Better-Tailored Treatments

In the last decade, alcohol consumption in the US has risen by 84% in women compared with 35% in men. Furthermore, research has shown that sex- and gender-related differences may disadvantage women in terms of developing a range of psychological, cognitive, and medical problems considerably earlier in their drinking history than men, and despite consuming a similar quantity of substances. While this "telescoping" process has been acknowledged in the literature, a concomitant understanding of the underlying biobehavioral mechanisms, and an increase in the development of specific treatments tailored to women, has not occurred. In the current chapter we focus on understanding why the need for personalized, sex-specific medications is imperative, and highlight some of the potential sex-specific gonadal and stress-related adaptations underpinning the accelerated progress from controlled to compulsive drug and alcohol seeking in women. We additionally discuss the efficacy of these mechanisms as novel targets for medications development, using exogenous progesterone and guanfacine as examples. Finally, we assess some of the challenges faced and progress made in terms of developing innovative medications in women. We suggest that agents such as exogenous progesterone and adrenergic medications, such as guanfacine, may provide some efficacy in terms of attenuating stress-induced craving for several substances, as well as improving the ability to emotionally regulate in the face of stress, preferentially in women. However, to fully leverage the potential of these therapeutics in substance-using women, greater focus needs to the placed on reducing barriers to treatment and research by encouraging women into clinical trials.