On the other hand, recent findings show that TLR2 deficiency increases susceptibility to learned helplessness, while TLR2 activation with the agonist Pam3CSK4 reverses stress-induced impairments in sociability and novel object recognition tests, suggesting a protective role of TLR2 stimulation against depression-like states [69]. This evidence concerns the gene TLR2 and depressive symptom measurement.