The CX3CR1 protein level did not differ in a trigeminal neuralgia model before or after BoNT treatment [16], but it was reported that the mRNA expression of this chemokine receptor selectively expressed in microglia was upregulated in scenarios of depression induced by chronic administration of reserpine in a Parkinson disease model, which was significantly decreased in the hippocampus in the experimental group using BoNT [18]. The gene discussed is CX3CR1; the disease is major depressive disorder.