2.7. Histamine-Induced Paw Edema in Rats

Doses of the extract were based on the study of Cavalher–Machado et al. [12]. The experiment was performed by using the method of Winter et al. [18] with slight modifications. After 12 h of fasting, Wistar rats were randomly divided into five groups (n = 3/sex/group). The first group received drinking water (10 mL/kg p.o.), whereas the second was treated with hydroxyzine (70 mg/kg, p.o.). The other groups were orally treated with S. terebinthifolius bark extract (100, 200, and 400 mg/kg, per os, respectively). Approximately 1 h after the treatments, edema was induced by the administration of histamine (0.1% w/v, 0.1 mL) in the right-hind paw's subplantar region. The results were obtained by the paw's volume difference before and after 0.5, 1, 2, 3, and 4 h of edema induction. Paw volume was measured by plethysmography (Model 7140, Ugo Basile, Varese, Italy).