Prevention of formalin-induced nociceptive behaviors caused by PPAR-gamma activation strengthened with cerebellar transcranial direct current stimulation

Abstract

The investigation was performed on 55 male Wistar rats. The pain behaviors were induced through the formalin (2.5%) subcutaneous administration into the plantar surface of the right hind paw. Pain score value was determined continuously during 90 min. It was established that combined usage of pioglitazone (100.0 mg/kg, i.p.) and cerebellar transcranial direct current stimulation (tDCS) (300 µA, 10.0 min) resulted in pronounced protection of pain behaviors at all stages of the pain syndrome development. The severity of investigated index decreased by 60.0% compared to the control data at 4-6 min after formalin administration (P<0.05). Averaged severity of pain behaviors was suppressed more than twice at Phase I and Interphase (P<0.05), by 60.0% at Phase 2A (P<0.05), and by 33.3% at Phase 2B (P<0.05). Pain -suppressive effect encompassed 42.0+8.25 min of Phase 2A and exceeded data in the group treated with tDCS by 39.1% (P<0.05) and in the group treated with pioglitazone by 64.3% (P<0.05). The conclusion was made that the pain-protective effect of pioglitazone is strengthened with cerebellar tDCS.