Figure 7.

Serotonin decrease in the hippocampus is mediated by histamine. A, Following 30 min of baseline serotonin collection, thioperamide was administered (50 mg/kg, i.p.; green, n = 5). Control animals were given saline (i.p.; blue, n = 10). Error (±SEM) is shown in a lighter color. A Student's t test was used to determine the first time a drug treatment induced statistically significant changes in serotonin from baseline measures. A gray dotted line denotes the first time point at which thioperamide produced decreased serotonin compared with averaged control serotonin (green, *; 8 min). A representative Bland–Altman plot to analyze FSCAV data can be seen in Figure 1. B, Schematic showing how histamine (HA) release acts on H3Rs located on serotonin (i.e., 5-HT) neurons to inhibit serotonin release. The actions of thioperamide on H3Rs are marked.