“…There are four known histamine receptors (H1R, H2R, H3R, H4R). H1R and H2R were originally studied for their role in depression, but these studies resulted in inconclusive results (Barnett et al, 1969; Horovitz et al, 1966; Katz & Sibel, 1982; Noguchi et al, 1992; O'Neill & Gertner, 1986; Wallach & Hedley, 1979; Willner, 1984). The H3R is of particular interest because it is it a presynaptic histamine autoreceptor that inhibits histamine synthesis (Arrang et al, 1987), histamine release (Arrang et al, 1987; Van der Werf et al, 1987), GABA release (Arias‐Montaño et al, 2001; Garcia et al, 1997; Yamamoto et al, 1997), NE release (Schlicker et al, 1989), 5HT release (Fink et al, 1990; Hashemi et al, 2011; Schlicker et al, 1988; Threlfell et al, 2004), and DA release (Schlicker et al, 1993).…”