Addressing the Current Knowledge and Gaps in Research Surrounding Lysergic Acid Diethylamide (LSD), Psilocybin, and Psilocin in Rodent Models.

Lysergic acid Diethylamide (LSD), psilocybin, and psilocin are being intensively evaluated as potential therapeutics to treat depression, anxiety, substance use disorder, and a host of other psychiatric illnesses. Pre-clinical investigation of these compounds in rodent models forms a key component of their drug development process. In this review, we will summarize the evidence gathered to date surrounding LSD, psilocybin, and psilocin in rodent models of the psychedelic experience, behavioural organization, substance use, alcohol consumption, drug discrimination, anxiety, depression-like behaviour, stress response, and pharmacokinetics.

Dual Cannabinoid and Orexin Regulation of Anhedonic Behaviour Caused by Prolonged Restraint Stress.

The endocannabinoid and orexin systems share many biological functions, including wakefulness, stress response, reward processing, and mood. While these systems work against one another with respect to arousal, chronic stress-induced downregulation of both systems often leads to anhedonia or the inability to experience pleasure from natural rewards. In the current study, a 24 h restraint stress test (24 h RST) reduced sucrose preference in adult male and female C57BL/6 mice.

Molecular and cellular mechanisms underlying brain region-specific endocannabinoid system modulation by estradiol across the rodent estrus cycle.

Neurological crosstalk between the endocannabinoid and estrogen systems has been a growing topic of discussion over the last decade. Although the main estrogenic ligand, estradiol (E2), influences endocannabinoid signaling in both male and female animals, the latter experiences significant and rhythmic fluctuations in E2 as well as other sex hormones. This is referred to as the menstrual cycle in women and the estrus cycle in rodents such as mice and rats.

Estradiol-dependent hypocretinergic/orexinergic behaviors throughout the estrous cycle.

Rationale: The female menstrual or estrous cycle and its associated fluctuations in circulating estradiol (E2), progesterone, and other gonadal hormones alter orexin or hypocretin peptide production and receptor activity. Depending on the estrous cycle phase, the transcription of prepro-orexin mRNA, post-translational modification of orexin peptide, and abundance of orexin receptors change in a brain region-specific manner. The most dramatic changes occur in the hypothalamus, which is considered the starting point of the hypothalamic-pituitary-gonadal axis as well as the hub of orexin-producing neurons.

Impact of the mouse estrus cycle on cannabinoid receptor agonist-induced molecular and behavioral outcomes.

Sexual dimorphisms are observed in cannabinoid pharmacology. It is widely reported that female animals are more sensitive to the cataleptic, hypothermic, antinociceptive, and anti-locomotive effects of cannabinoid receptor agonists such as CP55,940. Despite awareness of these sex differences, there is little consideration for the pharmacodynamic differences within females.

Evidence for Brain Region-Specific Molecular Interactions Between Cannabinoid and Orexin Receptors.

The endocannabinoid and orexin neuromodulatory systems serve key roles in many of the same biological functions such as sleep, appetite, pain processing, and emotional behaviors related to reward. The type 1 cannabinoid receptor (CB1R) and both subtypes of the orexin receptor, orexin receptor type 1 (OX1R) and orexin receptor type 2 (OX2R) are not only expressed in the same brain regions modulating these functions, but physically interact as heterodimers in recombinant and neuronal cell cultures. In the current study, male and female C57BL/6 mice were co-treated with the cannabinoid receptor agonist CP55,940 and either the OX2R antagonist TCS-OX2-29 or the dual orexin receptor antagonist (DORA) TCS-1102.

In vitro and in vivo pharmacological activity of minor cannabinoids isolated from Cannabis sativa.

The Cannabis sativa plant contains more than 120 cannabinoids. With the exceptions of ∆-tetrahydrocannabinol (∆-THC) and cannabidiol (CBD), comparatively little is known about the pharmacology of the less-abundant plant-derived (phyto) cannabinoids. The best-studied transducers of cannabinoid-dependent effects are type 1 and type 2 cannabinoid receptors (CB1R, CB2R).