Neuroprotective effects of curcumin and apocynin on spatial memory performance in an animal model of acute neuroinflammation / Efeitos neuroprotetores de curcumina e apocinina sobre o desempenho em memória espacial em modelo animal de neuroinflamação aguda

Abstract

Neuroinflammation is closely related to the etiology of several neurological/neurodegenerative diseases. These disorders cause cognitive impairment and sensitization of the immune system to internal and/or external stimuli. This work aims to evaluate the neuroprotective effects of the phytochemical compounds curcumin and apocynin on the spatial memory of rats in a model of acute neuroinflammation. For this, the study was divided into two phases. First, the dose of lipopolysaccharide (LPS) able to cause neuroinflammation and consequently mnemonic damage to the animals was tested. In the second phase, the neuroprotective effect of curcumin and apocynin was assessed. At two days after the surgery, the treatment with curcumin 50 mg/kg dissolved in vegetable oil was administered by gavage to saline + curcumin and LPS + curcumin groups. On the same day, animals from groups saline + apocynin and LPS + apocynin received by gavage apocynin 50 mg/kg suspended in distilled water. Rats of saline + vehicle and LPS + vehicle groups received vegetable oil or distilled water. The gavage treatment was given for 30 days for all groups. The spatial memory evaluation was assessed by Morris Water Maze (MWM) task, performed 30 days after the surgery in the first phase of the study and 1 day after the last gavage treatment in the second phase, both for 5 consecutive days. The MWM test trial was conducted 24 hours after the last training session. We found that the intra-hippocampal infusion of LPS, performed 30 days before training in the MWW task, impaired the retention of spatial memory acquired in this task. It also caused histopathological alterations in the infusion region, which are compatible with both acute and chronic neuroinflammation. Oral administration of apocynin, but not curcumin, reversed the mnemonic deficit and mitigated the histopathological alterations caused by the intra-hippocampal infusion of LPS.