The Influence of Fluoxetine on the Sensorimotor Function of the Sciatic Nerve in Wistar Rats after Axonotmesis: An Experimental Animal Model.

Background: Fluoxetine, a serotonin reuptake inhibitor antidepressant, raises extracellular serotonin levels and promotes angiogenesis and neurogenesis. Numerous animal models have shown its beneficial effects on recovery from peripheral nerve injury.

Purpose: The primary objective of this study was to analyze the influence of fluoxetine on the sensory-motor function recovery of the sciatic nerve in Wistar rats after axonotmesis.

Study Design, Setting, And Sample: This study utilized an experimental rat model, conducted in the laboratory at the Federal University of Pernambuco. The sample consisted of 40 male Wistar rats.

Predictor Variable: The primary predictor variable was the fluoxetine exposure. The animals were randomly divided into 4 groups (control and 3 experimental groups), with 10 animals in each group. They were injected subcutaneously with saline or fluoxetine 5, 10, and 20 mg/kg/day, respectively.

Main Outcome Variables: The main outcome variables were postoperative motor and sensory sciatic nerve function. Sensory nerve function was measured using the withdrawal reflex by thermostimulation. Motor nerve function was measured using the Sciatic Nerve Recovery Index and the Static Sciatic Nerve Index (SSI).

Covariates: None.

Analyses: Descriptive statistical analysis was performed using mean and SD. Analaysis of variance (ANOVA) was used for comparisons between the groups and Dunnett's multiple comparisons test was used in case of significant differences between the groups. Statistical Analysis System was the software used for statistical analyses.

Results: During the study, 15 animals were lost (3 in the control group and 4 in each experimental group), with no specific cause identified. On day 35, the latency time of the withdrawal reflex was significantly different, with decreased pain perception in the 5 mg/kg/day fluoxetine group (3.80 ± 1.20, P < .05). On day 14, the Sciatic Nerve Recovery Index showed greater deficits in the l0 and 20 mg/kg/day groups (-65.67 ± 7.20 and -63.57 ± 11.59, respectively) compared to the control group (P < .05). The SSI also showed a delay in recovery with the 10 mg/kg/day dose (-62.50 ± 6.72, P < .05).

Conclusion: The daily treatment with fluoxetine failed to bring any improvement to motor or sensory recuperation after injury to the sciatic nerve in Wistar rats.