Saponins of Tribulus terrestris attenuated neuropathic pain induced with vincristine through central and peripheral mechanism.

The study comprises exploring the effects of saponins from Tribulus terrestris (TT) in attenuating the neuropathic pain caused by vincristine (100 μg/ml i.p.) for 10 days (in two 5 day cycles with 2 days pause). Mechanical hyperalgesia and allodynia were assessed by Randall-Sellitto and electronic von Frey tests, respectively. Chemical- induced nociception was assessed by formalin test. Neurophysiological effect of the extract was evaluated by recording sciatic functional index (SFI) on the test days (7, 10, 14, and 21) and sciatic nerve conduction velocity test (SNCV) on the last day. Inflammatory mediators (TNF-α, IL-1β, and IL-6) in both sciatic nerve and brain and brain neurotransmitters, glutamate and aspartate, were measured to support the behavioral response. The saponins of TT-treated group were found to be effective in the behavioral experiments, implying its activity both centrally and peripherally in attenuating pain. The inflammatory mediators in both sciatic nerve and brain (TNF-α, IL-1β, and IL-6) were found to be attenuated with TT saponin treatment in comparison to vincristine-treated group, indicating its anti-inflammatory property. The excitatory neurotransmitters, L-glutamic acid and L-aspartic acid, were also found to be attenuated with TT saponins, implying restoration of neuronal damage and synaptic activity caused by high amount of glutamate due to excess TNF-α in brain and reversing the nociceptive threshold lowered due to aspartate. Thus, TT(S) is peripherally and centrally active in lowering the inflammatory mediators, reversing the neuronal damage and increasing the nociceptive threshold caused due to peripheral neuropathy.