Delayed administration of Trichilia catigua A. Juss. Ethyl-acetate fraction after cerebral ischemia prevents spatial memory deficits, decreases oxidative stress, and impacts neural plasticity in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Trichilia catigua A. Juss (Meliaceae) is used in Brazilian folk medicine to alleviate fatigue and emotional stress and improve memory. Previous studies from our laboratory reported that an ethyl-acetate fraction (EAF) of T. catigua that was given before cerebral ischemia in vivo prevented memory loss and reduced oxidative stress and neuroinflammation. Despite the value of these findings of a neuroprotective effect of T. catigua, treatment that was given immediately before or immediately after ischemia limits its clinical relevance. Thus, unknown is whether T. catigua possesses a specific time window of efficacy (TWE) when administered postischemia. AIM OF THE STUDY: Given continuity to previous studies, we investigated whether an EAF of T. catigua maintains its neuroprotective properties if treatment begins at different time windows of efficacy after ischemia. We also evaluated, for the first time, whether T. catigua possesses neuroplasticity/neurotrophic properties. MATERIAL AND METHODS: Rats were subjected to transient global brain ischemia (TGCI) and then given a single dose of the EAF (400 mg/kg) or vehicle (1 ml/kg) orally 1, 4, or 6 h postischemia. The levels of protein PCG, GSH, and GSSG, and activity of SOD and CAT were assayed as markers of oxidative stress on the day after ischemia. In another experiment, naive rats underwent spatial learning training in a radial maze task and then subjected to TGCI. Delayed treatment with the EAF began 4 or 6 h later and continued for 7 days. Retrograde memory performance was assessed 10, 17, and 24 days postischemia. Afterward, brains were examined for neurodegeneration and neuronal dendritic morphology in the hippocampus and cerebral cortex. Another group received the EAF at 4 h of reperfusion, and 4 days later their brains were examined for GFAP and Iba-1 immunoreactivity. Lastly, ischemic rats received the EAF 4 h after ischemia and neural plasticity-related proteins, BDNF, SYN, PSD 95, and NeuN were measured in the hippocampus 7 and 14 days after ischemia. RESULTS: A single EAF administration 1, 4, or 6 h postischemia alleviated oxidative stress that was caused by ischemia, expressed as a reduction of the amount of the PCG and GSSG, normalization of the GSH/GSSG ratio, and the restoration of SOD activity. Ischemia caused the persistent loss of memory (i.e., amnesia), an outcome that was consistently ameliorated by treatment with the EAF that was initiated 4 or 6 h postischemia. The 4 h delay in EAF treatment positively impacted dendritic morphology in neurons that survived ischemia. TGCI reduced BDNF, SYN, PSD-95, and NeuN protein levels in the hippocampus and cerebral cortex. The EAF normalized SYN and PSD-95 protein levels. Ischemia-induced neurodegeneration and glial cell activation were not prevented by EAF treatment. CONCLUSION: The present study corroborates prior data that demonstrated the neuroprotective potential of T. catigua and extends these data by showing that the delayed administration of EAF postischemia effectively prevented memory impairment and decreased oxidative stress, dendritic deterioration, and synaptic protein loss within a TWE that ranged from 1 to 6 h. This specific TWE in preclinical research may have clinical relevance by suggesting the possible utility of this plant for the development of neuroprotective strategies in the setting of ischemic brain diseases. Another innovative finding of the present study was the possible neurotrophic/neuroplastic properties of T. catigua.

Ethyl-acetate fraction of Trichilia catigua protects against oxidative stress and neuroinflammation after cerebral ischemia/reperfusion.

ETHNOPHARMACOLOGICAL RELEVANCE: Trichilia catigua A. Juss (Meliaceae) preparations have been used in folk medicine to alleviate fatigue, stress, and improve memory. Antinociceptive, antiinflammatory, and in vitro neuroprotective effects have been observed in animals. Cerebral ischemia/reperfusion (I/R) leads to severe neuropsychological deficits that are largely associated with oxidative stress, inflammation and neurodegeneration. We reported previously that an ethyl-acetate fraction (EAF) of T. catigua reduced brain ischemia-induced learning and memory impairments in the absence of histological protection. AIM OF THE STUDY: Continuing those studies, here we aimed to investigate the antioxidant and antiinflammatory properties of T. catigua in an in vivo model of I/R. MATERIAL AND METHODS: Rats were subjected to 15 min of brain ischemia (4-VO model) followed by up to 15 days of reperfusion. Vehicle was given by gavage 30 min before ischemia and at 1 h of reperfusion. In a first experiment, brain ischemia-induced changes in oxidative stress markers, i.e., reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and protein carbonyl groups (PCGs) were measured on days 1, 3, and 5 post-ischemia. Similar time course analysis was done for neuroinflammation markers, i.e., microglia (OX42 immunorreactivity) and astrocytes (GFAP immunorreactivity), in the hippocampus. In a second experiment, the time points at which these markers of oxidative stress and neuroinflammation peaked were used to test the effects of T. catigua (400 mg/kg, p.o.). RESULTS: Oxidative stress markers peaked on day 1 post-ischemia. GSH decreased (-23.2%) while GSSG increased (+ 71.1%), which yielded a significant reduction in the GSH/GSSG ratio (-39.1%). The activity of CAT was largely reduced by ischemia (-54.6% to -65.1%), while the concentration of PCG almost doubled in the brain of ischemic rats (+99.10%) in comparison to sham. Treatment with the EAF of T. catigua normalized these changes in oxidative markers to the control levels (GSH: +27.5%; GSSG: -23.8%; GSH/GSSG: +44.6%; PCG: -80.3%). In the hippocampus, neuroinflammation markers peaked on day 5 post-ischemia, with microglial and astrocytic responses increasing to 54.8% and 37.1%, respectively. The elevation in glial cells response was completely prevented by EAF. CONCLUSION: These results demonstrate that T. catigua has both antioxidant and antiinflammatory activities after transient global cerebral ischemia in rats, which may contribute to the previously reported memory protective effect of T. catigua.

Ethyl-acetate fraction of Trichilia catigua restores long-term retrograde memory and reduces oxidative stress and inflammation after global cerebral ischemia in rats.

We originally reported that an ethyl-acetate fraction (EAF) of Trichilia catigua prevented the impairment of water maze learning and hippocampal neurodegeneration after transient global cerebral (TGCI) in mice. We extended that previous study by evaluating whether T. catigua (i) prevents the loss of long-term retrograde memory assessed in the aversive radial maze (AvRM), (ii) confers hippocampal and cortical neuroprotection, and (iii) mitigates oxidative stress and neuroinflammation in rats that are subjected to the four vessel occlusion (4-VO) model of TGCI. In the first experiment, naive rats were trained in the AvRM and then subjected to TGCI. The EAF was administered orally 30min before and 1h after TGCI, and administration continued once per day for 7days post-ischemia. In the second experiment, the EAF was administered 30min before and 1h after TGCI, and protein carbonylation and myeloperoxidase (MPO) activity were assayed 24h and 5days later, respectively. Retrograde memory performance was assessed 8, 15, and 21days post-ischemia. Ischemia caused persistent retrograde amnesia, and this effect was prevented by T. catigua. This memory protection (or preservation) persisted even after the treatment was discontinued, despite the absence of histological neuroprotection. Protein carbonyl group content and MPO activity increased around 43% and 100%, respectively, after TGCI, which were abolished by the EAF of T. catigua. The administration of EAF did not coincide with the days of memory testing. The data indicate that antioxidant and/or antiinflammatory actions in the early phase of ischemia/reperfusion contribute to the long-term antiamnesic effect of T. catigua.

Postischemic fish oil treatment restores long-term retrograde memory and dendritic density: An analysis of the time window of efficacy.

We reported that fish oil (FO) prevented the loss of spatial memory caused by transient, global cerebral ischemia (TGCI), provided the treatment covered the first days prior to and after ischemia. Continuing these studies, trained rats were subjected to TGCI, and FO was administered for 10days, with a time window of efficacy (TWE) of 4, 8 or 12h post-ischemia. Retrograde memory was assessed up to 43days after TGCI. In another experiment, ischemic rats received FO with a 4- or 12-h TWE, and dendritic density was assessed in the hippocampus and cerebral cortex. The brain lipid profile was evaluated in sham-operated and ischemic rats that were treated with FO or vehicle with a 4-h TWE. Ischemia-induced retrograde amnesia was prevented by FO administration that was initiated with either a 4- or 8-h TWE. Fish oil was ineffective after a 12-h TWE. Independent of the TWE, FO did not prevent ischemic neuronal death. In the hippocampus, but not cerebral cortex, TGCI-induced dendritic loss was prevented by FO with a 4-h TWE but not 12-h TWE. The level of docosahexaenoic acid almost doubled in the hippocampus in ischemic, FO-treated rats (4-h TWE). The data indicate that (i) the anti-amnesic effect of FO can be observed with a TWE of up to 8h, (ii) the stimulation of dendritic neuroplasticity may have contributed to this effect, and (iii) DHA in FO may be the main active constituent in FO that mediates the cognitive and neuroplasticity effects on TGCI.

Robust and enduring atorvastatin-mediated memory recovery following the 4-vessel occlusion/internal carotid artery model of chronic cerebral hypoperfusion in middle-aged rats.

Chronic cerebral hypoperfusion (CCH) is a common condition associated with the development and/or worsening of age-related dementia.We previously reported persistent memory loss and neurodegeneration after CCH in middle-aged rats. Statin-mediated neuroprotection has been reported after acute cerebral ischemia. Unknown, however, is whether statins can alleviate the outcome of CCH. The present study investigated whether atorvastatin attenuates the cognitive and neurohistological outcome of CCH. Rats (12­15 months old) were trained in a non-food-rewarded radial maze, and then subjected to CCH. Atorvastatin (10 mg/kg, p.o.) was administered for 42 days or 15 days, beginning 5 h after the first occlusion stage. Retrograde memory performance was assessed at 7, 14, 21, 28, and 35 days of CCH, and expressed by "latency," "number of reference memory errors" and "number of working memory errors." Neurodegeneration was then examined at the hippocampus and cerebral cortex. Compared to sham, CCH caused profound and persistent memory loss in the vehicle-treated groups, as indicated by increased latency (91.2% to 107.3%) and number of errors (123.5% to 2508.2%), effects from which the animals did not spontaneously recover across time. This CCH-induced retrograde amnesia was completely prevented by atorvastatin (latency: −4.3% to 3.3%; reference/working errors: −2.5% to 45.7%), regardless of the treatment duration. This effect was sustained during the entire behavioral testing period (5 weeks), even after discontinuing treatment. This robust and sustained memory-protective effect of atorvastatin occurred in the absence of neuronal rescue (39.58% to 56.45% cell loss). We suggest that atorvastatin may be promising for the treatment of cognitive sequelae associated with CCH.