Anxiolytic properties of compounds that counteract oxidative stress, neuroinflammation, and glutamatergic dysfunction: a review

Objective: Anxiety disorders are highly prevalent and the efficacy of the available anxiolytic drugs is less than desired. Adverse effects also compromise patient quality of life and adherence to treatment. Accumulating evidence shows that the pathophysiology of anxiety and related disorders is multifactorial, involving oxidative stress, neuroinflammation, and glutamatergic dysfunction. The aim of this review was to evaluate data from animal studies and clinical trials showing the anxiolytic effects of agents whose mechanisms of action target these multiple domains. Methods: The PubMed database was searched for multitarget agents that had been evaluated in animal models of anxiety, as well as randomized double-blind placebo-controlled clinical trials of anxiety and/or anxiety related disorders. Results: The main multitarget agents that have shown consistent anxiolytic effects in various animal models of anxiety, as well in clinical trials, are agomelatine, N-acetylcysteine (NAC), and omega-3 fatty acids. Data from clinical trials are preliminary at best, but reveal good safety profiles and tolerance to adverse effects. Conclusion: Agomelatine, NAC and omega-3 fatty acids show beneficial effects in clinical conditions where mainstream treatments are ineffective. These three multitarget agents are considered promising candidates for innovative, effective, and better-tolerated anxiolytics.

Effects of N-acetylcysteine on amphetamine-induced sensitization in mice

Objective: N-acetylcysteine (NAC) is beneficial in psychiatric conditions, including schizophrenia. Patients with schizophrenia exhibit mesolimbic dopamine hyperfunction consequent to an endogenous sensitization process. This sensitization can be modeled in rodents by repeated exposure to psychostimulants, provoking an enduring amplified response at subsequent exposure. The aim of this study was to investigate the effects of NAC on amphetamine sensitization in mice. Methods: D-amphetamine was administered to C57BL/6 mice three times a week for 3 weeks; the dose was increased weekly from 1 to 3 mg/kg. NAC (60 mg/kg) or saline was administered intraperitoneally before saline or amphetamine during the second and third weeks. After a 4-week washout period, latent inhibition (LI) and the locomotor response to amphetamine 2 mg/kg were assessed. Results: Sensitization disrupted LI and amplified the locomotor response; NAC disrupted LI in control mice. In sensitized animals, NAC attenuated the enhanced locomotion but failed to prevent LI disruption. Conclusion: NAC warrants consideration as a candidate for early intervention in ultra-high risk subjects due to its safety profile and the relevance of its mechanism of action. Supplementing this proposition, we report that NAC attenuates sensitization-induced locomotor enhancement in mice. The finding that NAC disrupted LI incites a cautionary note and requires clarification.

Differential susceptibility of BALB/c, C57BL/6N, and CF1 mice to photoperiod changes

Objective:Circadian disturbances common to modern lifestyles have been associated with mood disorders. Animal models that mimic such rhythm disturbances are useful in translational research to explore factors contributing to depressive disorders. This study aimed to verify the susceptibility of BALB/c, C57BL/6N, and CF1 mice to photoperiod changes.Methods:Thermochron iButtons implanted in the mouse abdomen were used to characterize temperature rhythms. Mice were maintained under a 12:12 h light-dark (LD) cycle for 15 days, followed by a 10:10 h LD cycle for 10 days. Cosinor analysis, Rayleigh z test, periodograms, and Fourier analysis were used to analyze rhythm parameters. Paired Student's t test was used to compare temperature amplitude, period, and power of the first harmonic between normal and shortened cycles.Results:The shortened LD cycle significantly changed temperature acrophases and rhythm amplitude in all mouse strains, but only BALB/c showed altered period.Conclusion:These findings suggest that BALB/c, the preferred strain for stress-induced models of depression, should also be favored for exploring the relationship between circadian rhythms and mood. Temperature rhythm proved to be a useful parameter for characterizing rhythm disruption in mice. Although disruption of temperature rhythm has been successfully documented in untethered mice, an evaluation of desynchronization of other rhythms is warranted.

Temperament and character traits associated with the use of alcohol, cannabis, cocaine, benzodiazepines, and hallucinogens: evidence from a large Brazilian web survey

Objectives: To evaluate how personality traits are associated with occasional use, abuse, and dependence of alcohol, cannabis, cocaine, benzodiazepines, and hallucinogens in a large availability sample of adults via online questionnaires. Methods: The sample consisted of 8,646 individuals (24.7% men and 75.3% women) who completed an anonymous web survey. Involvement with drugs and temperament/character traits were assessed through the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) and the Temperament and Character Inventory - Revised (TCI-R), respectively. Interactions among variables were analyzed using MANOVA with Bonferroni adjustment. Results: Novelty seeking was the trait most associated with increased involvement with alcohol, cannabis, and cocaine. There was a significant association between harm avoidance and benzodiazepine use. Persistence was lower in cannabis-, benzodiazepine-, and cocaine-dependent subjects, as well as in hallucinogen abusers. Self-directedness was reduced in dependents of all drug classes. No strong relationships were found between other temperament or character dimensions and the severity of drug use. Conclusions: Novelty seeking was associated with increased involvement with all drugs studied in this sample, although to a lesser extent with benzodiazepines and hallucinogens. The temperament and character profile for benzodiazepine use was different from that of other drugs due to the relationship with higher harm avoidance and self-transcendence and lower self-directedness. .

Merging ethnoppharmacology with chemotaxonomy: An approach to unveil bioactive natural products. The case of Psychotria alkaloids as potential analgesics

Psychotria colorata (Will ex R&S) Muell.Arg. flowers are used by "caboclos" in the Amazon as the basis for a homemade analgesic. The study of P. colorata revealed the presence of several pyrrolidinoindoline alkaloids, some with opioid-like analgesic activity in vivo. Neurochemical studies of active alkaloids proved their capability of inhibiting [3H] naloxone binding, confirming the opioid nature of the analgesic activity. These data launched a broader screening of Psychotria species, including P. carthagenensis, P. brachyceras, P. leiocarpa, P. myriantha, P. suterella and P. brachypoda. The analysis of the analgesic activity of several Psychotria species, as well as of specific isolated compounds, allowed a tentative structure/activity relationship and opened a promising research avenue in the search for new analgesic drugs.