Rauvolfia vomitoria phenol extract relieves pentylenetetrazol-induced seizures in Swiss mice and protects some temporal lobe structures

Abstract

Background: Rauvolfia vomitoria (R. vomitoria) is a plant of economic importance due to its diverse ethnomedicinal properties, including the anticonvulsant effect. In this study, we studied the antiseizure and neuroprotective potentials of R. vomitoria extracts against pentylenetetrazol (PTZ)-induced kindling.

Methods: Twenty-five adult Swiss mice (25-30 g) were assigned to five groups (n = 5): control group, PTZ treatment group, and PTZ treatment after receiving oral R. vomitoria crude extract (100 mg/kg), R. vomitoria phenol extract (50 mg/kg) or sodium valproate (15 mg/kg) every 48 h for 28 days. Seizure scores, cognitive behavioral tests including novel object test, Y-maze test, and the elevated plus maze test, as well as brain neurochemicals and histomorphology studies, were performed.

Results: Compared with the control group, the PTZ group showed comparable body weight and durations in closed and open arms (P > 0.05), but preference for familiar objects, significant (P < 0.05) spontaneous alternation, increased monoamine oxidase activity and nitric oxide level, and Nissl chromatolysis in the temporal lobe structures including the cortex, hippocampus, and amygdala. R. vomitoria phenol extract pretreatment significantly (P < 0.05) reduced seizures, prevented adverse cognitive behaviors, decreased the nitric oxide level, and reduced the temporal lobe Nissl chromatolysis compared with the R. vomitoria crude extract pretreatment group and the sodium valproate pretreatment groups.

Conclusions: Thus, R. vomitoria phenol extract showed promising results against seizures and potential for general brain protection, suggesting that the anticonvulsant property of R. vomitoria may be attributed to its phenol constituent. More studies are needed to delineate the mechanisms of its action.

Keywords: Cognitive behaviour; Neurochemicals; Seizure; Sodium valproate; Swiss mice; Temporal lobe.

Fig. 1

Quantitative analysis of phytochemical compositions of R. vomitoria root bark

Fig. 2

Mouse body weights at the start of study and at sacrifice. One-way analysis of variance followed by Tukey's multiple comparison test; n = 5 mice in each group. IBW, initial body weight; FBW, final body weight; PTZ, pentylenetetrazol; RV, R. vomitoria crude extract; RVp, R. vomitoria phenol extract; SV, sodium valproate. *P < 0.05 vs SV+PTZ group; **P < 0.01 vs CTR, PTZ, SV+PTZ groups

Fig. 3

Racine seizure scores in the groups. One-way analysis of variance followed by Tukey's Multiple Comparison Test; n = 5; PTZ, pentylenetetrazol; RV, R. vomitoria crude extract; RVp, R. vomitoria phenol extract; SV, sodium valproate. *P < 0.05 vs the PTZ group

Fig. 4

Novel object recognition of mice in the experimental groups. One-way analysis of variance followed by Tukey's Multiple Comparison Test; n = 5; PTZ, pentylenetetrazol; RV, R. vomitoria crude extract; RVp, R. vomitoria phenol extract; SV, sodium valproate. *P< 0.05 vs the CTR group; **P< 0.01 vs the CTR group;***P< 0.001 vs the CTR group; ^bP< 0.05 vs the PTZ group; ^cP < 0.05 vs the RV+PTZ group; ^dP < 0.05 vs the RVp+PTZ group

Fig. 5

Spontaneous alternations of mice. One-way analysis of variance followed by Tukey's Multiple Comparison Test; n = 5; PTZ, pentylenetetrazol; RV, R. vomitoria crude extract; RVp, R. vomitoria phenol extract; SV, sodium valproate. *P< 0.05 vs the CTR group; ***P < 0.001 vs the CTR group; ^bP < 0.05 vs the PTZ group; ^cP < 0.05 vs the RV+PTZ group

Fig. 6

Anxiety-like behavior in the elevated plus maze. One-way analysis of variance followed by Tukey's Multiple Comparison Test; n = 5; PTZ, pentylenetetrazol; RV, R. vomitoria crude extract; RVp, R. vomitoria phenol extract; SV, sodium valproate. There was no significant difference among the groups

Fig. 7

Biomoelcules in the mouse brain in the experimental groups. a GDH (glutamate dehydrogenase) activities in the brain. b MAO activities in the brain. c NO levels in the brain. One-way analysis of variance followed by Tukey's Multiple Comparison Test; n = 5; PTZ, pentylenetetrazol; RV, R. vomitoria crude extract; RVp, R. vomitoria phenol extract; SV, sodium valproate. **P < 0.01 vs the CTR group; ***P < 0.001 vs the CTR group

Fig. 8

Nissl staining in the hippocampal CA3 region. a Well-expressed Nissl in the control group. b Some less-expressed Nissl in the PTZ group. c Moderately-expressed Nissl in the R. vomitoria crude extract pretreatment group. d Well-expressed Nissl in the R. vomitoria phenol extract pretreatment group. e Well-expressed Nissl in the sodium valproate pretreatment group. M, molecular layer; P, pyramidal layer; Pm, polymorphic layer. Black arrows indicate dense staining, and black arrowheads indicate weak staining. Cresyl violet, ×400

Fig. 9

Nissl staining in the amygdala. a Well-expressed Nissl staining in the control group. b Moderate-expressed Nissl staining in the R. vomitoria crude extract pretreatment group. c Less-expressed Nissl staining in the PTZ group. d Well-expressed Nissl staining in the R. vomitoria phenol extract pretreatment group. e Well-expressed Nissl in the sodium valproate pretreatment group. Black arrows indicate dense staining, and black arrowheads indicate weak staining. Cresyl violet, ×400

Fig. 10

Nissl staining in the temporal cortical layers. a Nissl staining in the control group. b Weak Nissl staining in the PTZ group. C Weak Nissl staining in the R. vomitoria crude extract pretreatment group. d Well-expressed Nissl in the R. vomitoria phenol extract pretreatment group. e Well-expressed Nissl in the sodium valproate pretreatment group. M, molecular layer; P, pyramidal layer; Pm, polymorphic layer. Black arrows indicate dense staining, and black arrowheads indicate weak staining. Cresyl violet, ×400