TY - JOUR T1 - 5-HT<sub>2A</sub> Receptor Agonist-Induced Hyperthermia Is Induced via Vasoconstriction by Peripheral 5-HT<sub>2A</sub> Receptors and Brown Adipose Tissue Thermogenesis by Peripheral Serotonin Loss at a High Ambient Temperature JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 356 LP - 362 DO - 10.1124/jpet.118.250217 VL - 367 IS - 2 AU - Mami Nakamura AU - Kaori Shintani-Ishida AU - Hiroshi Ikegaya Y1 - 2018/11/01 UR - http://jpet.aspetjournals.org/content/367/2/356.abstract N2 - Recreational drugs such as 3,4-methylenedioxymethamphetamine and cocaine induce hyperthermia, which is affected by ambient temperature. 2-(4-Bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine (25B-NBOMe), a selective agonist of 5-HT2A receptor used as a recreational drug, reportedly induces hyperthermia. This study aimed to verify whether 25B-NBOMe induces ambient temperature-dependent hyperthermia and to clarify its mechanism. Eight-week-old male Sprague-Dawley rats were administered intraperitoneal injection of 25B-NBOMe at an ambient temperature of 23°C or 29°C. 25B-NBOMe administration at 23°C did not change the core body temperature of the rats, whereas administration at 29°C induced significant hyperthermia 30–120 minutes postadministration. Tail surface temperature temporarily decreased 30 minutes postadministration, indicating heat storage by peripheral vasoconstriction despite a high ambient temperature. Because 25B-NBOMe-induced-hyperthermia was suppressed by sarpogrelate, but not by destruction of central noradrenaline or serotonin neurons, peripheral 5-HT2A receptors were considered contributors to the development of hyperthermia at a high ambient temperature, independently from central neurons. The temperature of brown adipose tissue (BAT) increased 60–120 minutes postadministration of 25B-NBOMe at 29°C, indicating thermogenesis. Previous studies have reported that peripheral serotonin contributes to the inhibition of BAT thermogenesis. Decreased plasma serotonin levels were observed at 29°C, and serotonin administration partially suppressed 25B-NBOMe-induced hyperthermia at a high ambient temperature, suggesting that decreased levels of peripheral serotonin induced BAT thermogenesis. Our findings indicate that 25B-NBOMe induces hyperthermia at a high ambient temperature via vasoconstriction regulated by 5-HT2A receptors and BAT thermogenesis mediated by decreased levels of plasma serotonin. Thus, peripheral serotonin plays a partial but important role in thermoregulation. ER -