“…Fasting also increases serotonin-induced intracellular calcium cation concentration, a proposed correlate of 5-HT2AR function in the brain ( Sudo et al., 1997 ), as stimulation of 5-HT2ARs induces intracellular calcium release ( Raote et al, 2007 ). Increases in cortical brain-derived neurotrophic factor (BDNF), as well as the antidepressant and anti-inflammatory effects of fasting ( Cui et al., 2018 ; Fond et al, 2013 ), are consistent with the effects of 5-HT2AR activation ( Carhart-Harris et al., 2016a ; Cui et al, 2018 ; Flanagan et al, 2019b ; Jaggar and Vaidya, 2018 ). Acute fasting and intermittent religious fasting have been shown to increase 5-HT levels and metabolism ( Bastani et al, 2017 ; Fuenmayor and Garcia, 1984 ; Ishida et al, 1997 ; although see Bubenik et al, 1992 ) whereas longer-term tryptophan depletion or starvation may decrease 5-HT levels ( Cahir et al, 2007 ; Haider and Haleem, 2000 ).…”