Assessing the effects of 5-HT2A and 5-HT5A receptor antagonists on DOI-induced head-twitch response in male rats using marker-less deep learning algorithms

BACKGROUND

Serotonergic psychedelics, which display a high affinity and specificity for 5-HT2A receptors like 2,5-dimethoxy-4-iodoamphetamine (DOI), reliably induce a head-twitch response in rodents characterized by paroxysmal, high-frequency head rotations. Traditionally, this behavior is manually counted by a trained observer. Although automation could simplify and facilitate data collection, current techniques require the surgical implantation of magnetic markers into the rodent's skull or ear.

METHODS

This study aimed to assess the feasibility of a marker-less workflow for detecting head-twitch responses using deep learning algorithms. High-speed videos were analyzed using the DeepLabCut neural network to track head movements, and the Simple Behavioral Analysis (SimBA) toolkit was employed to build models identifying specific head-twitch responses.

RESULTS

In studying DOI (0.3125-2.5 mg/kg) effects, the deep learning algorithm workflow demonstrated a significant correlation with human observations. As expected, the preferential 5-HT2A receptor antagonist ketanserin (0.625 mg/kg) attenuated DOI (1.25 mg/kg)-induced head-twitch responses. In contrast, the 5-HT5A receptor antagonists SB 699,551 (3 and 10 mg/kg), and ASP 5736 (0.01 and 0.03 mg/kg) failed to do so.

CONCLUSIONS

Previous drug discrimination studies demonstrated that the 5-HT5A receptor antagonists attenuated the interoceptive cue of a potent hallucinogen LSD, suggesting their anti-hallucinatory effects. Nonetheless, the present results were not surprising and support the head-twitch response as selective for 5-HT2A and not 5-HT5A receptor activation. We conclude that the DeepLabCut and SimBA toolkits offer a high level of objectivity and can accurately and efficiently identify compounds that induce or inhibit head-twitch responses, making them valuable tools for high-throughput research.

Psychedelics for the Treatment of Obsessive-Compulsive Disorder: Efficacy and Proposed Mechanisms

Psychedelics are emerging as potential treatments for a range of mental health conditions, including anxiety and depression, treatment-resistant depression, and substance use disorders. Recent studies have also suggested that the psychedelic psilocybin may be able to treat obsessive-compulsive disorder (OCD). Since the 1960s, case studies have reported improvements to obsessive and compulsive behaviors in patients taking psychedelics recreationally. The effects of psilocybin were then systematically assessed in a small, open-label trial in 2006, which found that psilocybin significantly reduced the symptoms of OCD. Reduced compulsive behaviors have also been seen in rodent models of OCD after administration of psilocybin. Nonetheless, the mechanisms underlying the effects of psychedelics for OCD are unclear, with hypotheses including their acute pharmacological effects, changes in neuroplasticity and resting state neural networks, and their psychological effects. This review will evaluate the evidence supporting the theory that psychedelics can be used for the treatment of OCD, as well as the data regarding claims about their mechanisms. It will also discuss issues with the current evidence and the ongoing trials of psilocybin that aim to address these knowledge gaps.

Obsessive compulsive disorder: overview of the condition and its nursing management

Obsessive compulsive disorder (OCD) is a complex condition characterised by intrusive and distressing thoughts (obsessions) and repetitive behaviours or mental acts (compulsions). The symptoms of OCD cause significant distress and anxiety and can have a debilitating effect on a person's daily functioning. This article gives an overview of OCD, including its prevalence, aetiology, symptoms and treatment strategies, with the aim of enhancing nurses' understanding of the condition and its adverse effects on a person's life. The author also discusses some of the ways in which nurses in any setting can support a person with OCD.

Psychedelic therapy for body dysmorphic disorder

In this opinion piece we propose the investigation of psychedelic-assisted psychotherapy for the treatment of body dysmorphic disorder (BDD). BDD is a psychiatric disorder characterised by appearance-based preoccupations and accompanying compulsions. While safe and effective treatments for BDD exist, non-response and relapse rates remain high. Therefore, there is a need to investigate promising new treatment options for this highly debilitating condition. Preliminary evidence suggests safety, feasibility, and potential efficacy of psychedelic treatments in disorders that share similar psychopathological mechanisms with BDD. Drawing on this evidence, as well as on relevant qualitative reports and theoretical proposals, we argue that it would be worthwhile to conduct a phase 2a study aimed at assessing the safety and feasibility of psychedelic-assisted psychotherapy in BDD. We also offer some suggestions for how future research ought to proceed.