LSD causes both behavioral changes and skin darkening in fish and amphibians. In the teleost fish Betta splendens, LSD produces distinct darkening. In female guppies (Poecilia reticulatus), LSD induces marked pigment dispersion in melanophores both in living fish and in isolated tissue, suggesting a direct action on the dermal melanophores.
Neurophysin I (NP-I), a stable byproduct of the oxytocin precursor, can serve as a reliable biomarker for oxytocin secretion when stimulated by MDMA. In a double-blind, placebo-controlled crossover study, 15 patients with hypothalamic-posterior-pituitary dysfunction and 15 matched healthy controls received a single 100 mg dose of MDMA or placebo. In healthy controls, MDMA caused an 8-fold increase in oxytocin (peak: 624 pM) and a 20-fold increase in NP-I (peak: 1508 pM). Patients showed no notable oxytocin increase (peak: 92 pM) and only a mild NP-I rise (peak: 263 pM). The difference in NP-I area under the curve between groups was significant (2340 pM·5 h; 95% CI, 1462-3218). NP-I measurement offers a way to assess oxytocin secretion, aiding research into conditions like autism, anxiety, and depression.