Low indoleamine 2, 3 dioxygenase (IDO) activity is associated with psycho-obstetric risk

Psilocin alleviates acute itch in mice: possible involvement of 5-HT2A receptors and kynurenine pathway

We aimed to investigate whether psilocin, the bioactive metabolite of the well-known psychedelic, psilocybin, may have antipruritic effects in mice by interfering with the kynurenine pathway and interacting with 5-HT2A receptors. Eight mice were randomly assigned to each of the study groups receiving either normal saline, compound 48/80, psilocin (0.3, 1, and 3 mg/kg), or psilocin (1 mg/kg) + 1-MT (0.3 mg/kg). The scratching bouts were documented in each group. The hallucinogenic properties of psilocin were documented using the head-twitch response (HTR) test. To confirm their involvement, we also quantified the expression levels of TNF-α, TLR-4, indoleamine-2,3-dioxygenase (IDO), and 5-HT2A receptors across various study groups. We found that psilocin (1 mg/kg) exerted the most significant antipruritic and hallucinogenic effects (P < 0.0001). The activity of 5-HT2A receptors in the skin tissue of mice was confirmed by western blot. When psilocin (1 mg/kg) was given together with 1-MT (0.3 mg/kg), the antipruritic effects became more pronounced as compared to when psilocin was given alone (P < 0.05). TLR-4 and TNF-α expression levels considerably reduced after psilocin was applied, both alone and together with 1-MT (P < 0.05, P < 0.01, respectively). We also observed significantly decreased activity of IDO in the treatment groups (P < 0.05, P < 0.01 after giving psilocin alone, and together with 1-MT, respectively). To our knowledge, this is the first study to confirm the effectiveness of psychedelics in battling pruritus. Our findings offer a novel repositioning for psilocin. This may be particularly beneficial for psychological conditions accompanied by pruritus.

The role of the placenta-brain axis in psychoneuroimmune programming

Gestational exposures have enduring impacts on brain and neuroimmune development and function. Perturbations of pregnancy leading to placental structure/function deficits, cell stress, immune activation, and endocrine changes (metabolic, growth factors, etc.) all increase neuropsychiatric risk in offspring. The existing literature links obstetric diseases with placental involvement to offspring neuroimmune outcomes and neurodevelopmental risk. Psychoneuroimmune outcomes in offspring brain include changes to microglia, cytokine/chemokine production, cell stress, and long-term immunoreactivity. These outcomes are altered by structural, anti-angiogenic/hypoxic, inflammatory, and metabolic diseases of the placenta. This fetal programming occurs via direct placental passage or production of factors which can act directly on fetal brain substrates, or indirectly via action of circulating factors on intermediates in the placenta. Placental neuroendocrine, vascular/angiogenic, immune, and extracellular vesicular mechanisms are detailed. These mechanisms interact within various placental and pregnancy conditions. An increased understanding of the placental origins of psychoneuroimmunology will yield dividends for human health. Identifying maternal and placental biomarkers for fetal neuroimmune health may also revolutionize early diagnosis and precision psychiatry, empowering patients to make the best healthcare decisions for their families. Targeting placental mechanisms may be a valuable approach for the prevention and mitigation of intergenerational, lifelong neuropathology.