Evaluation of Isolated Vascular Response to 5HT1A, 5HT1B1D & 5HT2A Receptors Agonist & Antagonist in Chronic Endotoxemic Rats

The main vascular feature in endotoxemia is impaired contractile responses to vasoactive agents. We study the aortic response to 5HT11 A, 5HT1B1D and 5HT2A receptors agonist and antagonist in chronic endotoxemic rats. Intraperitoneal injection of 1 mg/kg lipopolysaccharide for 5 days induced chronic endotoxemia. Control rats received intraperitoneal injection of 1 ml/kg saline for 5 days. Rats divided into 3 groups. In first, DOI2 hydrochloride used as an agonist and sarpogrelate hydrochloride as an antagonist of 5HT2A receptor. In second, (R)-(+)-8-OH-DPAT3 and WAY1001354 used as an agonist and antagonist of 5HT1A receptor respectively. In third, Zolmitriptan used as an agonist and GR127935 hydrochloride as an antagonist of 5HT1B1D receptor. Aorta Isolated for organ bath study. Real time-PCR5 and histopathological study examined receptors gene expression and protein localization. Cumulative 8-OH-DPAT caused relaxation in control aorta (EC506 7.79±21.35 and 8.53±10.74 with and without antagonist), which was enhanced in endotoxemia (EC50 6.35±8.48 and very wide±17.38 with and without antagonist). Cumulative zolmitriptan caused relaxation in control aorta (EC50 very wide±8.65 and 8.38±8.44 with and without antagonist), which was enhanced in endotoxemia (EC50 very wide±9.53 and 8.37±13.49 with and without antagonist). DOI hydrochloride contracted the control aorta (EC50 6.51±7.14 and 5.98±1.65 with and without antagonist), which was converted to relaxation in endotoxemic group (EC50 infinity±80.43 and 7.37±20.28 with and without antagonist). PCR studies revealed enhanced 5HT1A receptor and diminished 5HT1B1D and 5HT2A receptor genes expression, while histopathological studies showed inflamed, damaged endothelium in endotoxemic aorta. Our data supports enhanced vasodilation and impaired vasoconstriction during endotoxemia.

Serotonin 2A Receptor Signaling Underlies LSD-induced Alteration of the Neural Response to Dynamic Changes in Music

Classic psychedelic drugs (serotonin 2A, or 5HT2A, receptor agonists) have notable effects on music listening. In the current report, blood oxygen level-dependent (BOLD) signal was collected during music listening in 25 healthy adults after administration of placebo, lysergic acid diethylamide (LSD), and LSD pretreated with the 5HT2A antagonist ketanserin, to investigate the role of 5HT2A receptor signaling in the neural response to the time-varying tonal structure of music. Tonality-tracking analysis of BOLD data revealed that 5HT2A receptor signaling alters the neural response to music in brain regions supporting basic and higher-level musical and auditory processing, and areas involved in memory, emotion, and self-referential processing. This suggests a critical role of 5HT2A receptor signaling in supporting the neural tracking of dynamic tonal structure in music, as well as in supporting the associated increases in emotionality, connectedness, and meaningfulness in response to music that are commonly observed after the administration of LSD and other psychedelics. Together, these findings inform the neuropsychopharmacology of music perception and cognition, meaningful music listening experiences, and altered perception of music during psychedelic experiences.