Automated Computer Software Assessment of 5-Hydroxytryptamine 2A Receptor-Mediated Head Twitch Responses from Video Recordings of Mice

Abstract

Psychedelics are a class of drugs that produce unique subjective effects via agonist actions at the 5-hydroxytryptamine 2A receptor (5-HT 2A ). The 5-HT 2A -mediated head twitch response (HTR) in rodents is used as a reliable proxy for psychedelic drug activity in humans, but existing methods for measuring HTRs require surgery or time-consuming visual scoring. In the present work, we validated a simple noninvasive method for quantitating HTRs using computer-based analysis of experimental video recordings. Male C57BL/6J mice received injections of the 5-HT 2 receptor agonist (±)2,5-dimethoxy-4-iodoamphetamine (DOI; 0.03−3 mg/kg, s.c.) and were placed into cylindrical arenas. High frame rate videos were recorded via cameras mounted above the arenas. Antagonist experiments, which entailed pretreatment with the 5-HT 2A antagonist M100907 (0.01 or 0.1 mg/kg s.c.) prior to DOI (1 mg/kg s.c.), were also recorded. The experimental videos were analyzed for HTRs using a newly developed feature of a commercial software package and compared to visual scoring carried out by trained observers. As expected, DOI produced dose-related increases in HTRs, which were blocked by M100907. Computer scoring was positively correlated with visual scoring, and no statistical difference between the two methods was found. The software captured nearly all visually observed HTRs, false positives induced by other behaviors (e.g., grooming) were rare and easily identified, and results were improved by optimizing lighting conditions. Our findings demonstrate the utility of combining high frame rate video recordings with commercial software analyses to measure HTRs, validating an additional reliable method to study psychedelic-like drug activity in mice.

Structure–Activity Relationships for Psilocybin, Baeocystin, Aeruginascin, and Related Analogues to Produce Pharmacological Effects in Mice

“…40,61,81 Here, we quantified HTR in mice using a novel automated computer software-based scoring method recently validated in our laboratory. 82 We found that tertiary amines� psilocin, psilocybin, and psilacetin�induce dose-related increases in HTR, whereas secondary amines and quaternary ammoniums do not. The HTR produced by tertiary amines was completely blocked by pretreatment with the 5-HT 2A antagonist M100907.…”

“…The HTR is a widely used behavioral proxy for 5-HT 2A -mediated psychedelic-like drug activity in rodent models. ,, Here, we quantified HTR in mice using a novel automated computer software-based scoring method recently validated in our laboratory . We found that tertiary aminespsilocin, psilocybin, and psilacetininduce dose-related increases in HTR, whereas secondary amines and quaternary ammoniums do not.…”

“…For each experiment, mice were acclimated to the testing room in their home cage for at least 1 h prior to experimental sessions. Behavioral test sessions were carried out in Tru Scan mouse locomotor arenas equipped with photobeam arrays (Coulbourn Instruments, Holliston, MA, USA), which were modified with cylindrical inserts and transparent floors useful in detecting mouse HTR as described previously …”

Role of 5-HT2A, 5-HT2C, 5-HT1A and TAAR1 receptors in the head twitch response induced by 5-hydroxytryptophan and psilocybin: Translational implications

“…When using magnetometer recording of HTR, the software used can distinguish between the frequency induced by HTR and the frequency associated with other head movements (de la Fuente Revenga et al, 2019). An alternative, recently described tool for measuring HTRs in a non-invasive way is the TopScan (Clever Sys Inc, Reston, VA) computer software-based scoring (Glatfelter et al, 2022) system. This system is limited to one mouse per recording box.…”

“…An alternative, recently described tool for measuring HTRs in a non-invasive way is the TopScan (Clever Sys Inc, Reston, VA) computer software-based scoring (Glatfelter et al, 2022) system. This system is limited to one mouse per recording box.…”