Effect of Pioglitazone on Perihematomal Edema in Intracerebral Hemorrhage Mouse Model by Regulating NLRP3 Expression and Energy Metabolism

Abstract

Objective: Cerebral edema is the predominant mechanism of secondary inflammation after intracerebral hemorrhage (ICH). Pioglitazone, peroxisome proliferator-activated receptor gamma agonist has been shown to play a role in regulation of central nervous system inflammation. Here, we examined the pharmacological effects of pioglitazone in an ICH mouse model and investigated its regulation on NLRP3 inflammasome and glucose metabolism.

Methods: The ICH model was established in C57 BL/6 mice by the stereotactical inoculation of blood (30 µL) into the right frontal lobe. The treatment group was administered i.p. pioglitazone (20 mg/kg) for 1, 3, and 6 days. The control group was administered i.p. phosphate-buffered saline for 1, 3, and 6 days. We investigated brain water contents, NLRP3 expression, and changes in the metabolites in the ICH model using liquid chromatography-tandem mass spectrometry.

Results: On day 3, brain edema in the mice treated with pioglitazone was decreased more than that in the control group. Expression levels of NLRP3 in the ICH model treated with pioglitazone were decreased more than those of the control mice on days 3 and 7. The pioglitazone group showed higher levels of glycolytic metabolites than those in the ICH mice. Lactate production was increased in the ICH mice treated with pioglitazone.

Conclusion: Our results demonstrated less brain swelling following ICH in mice treated with pioglitazone. Pioglitazone decreased NLRP3-related brain edema and increased anaerobic glycolysis, resulting in the production of lactate in the ICH mice model. NLRP3 might be a therapeutic target for ICH recovery.

Keywords: Brain edema; Cerebral hemorrhage; Inflammasomes; Lactates; Pioglitazone.

Fig. 1.

Establishment of intracranial hemorrhage (IcH) models (hematoxylin and eosin, H&E). coronal section of the whole brain (A, scale bar=3 mm) and magnification of the hematoma (B, ×200).

Fig. 2.

Treatment schedule.

Fig. 3.

comparison of brain water contents. The water contents of both hemispheres in IcH mice treated with pioglitazone were lower than those in IcH mice on days 3 and 7. In the treatment group, the water content of the ipsilateral hemispheres on day 7 was decreased more than on day 3 (n = 7, each group). ^*p<0.05. IcH : intracranial hemorrhage.

Fig. 4.

Western blot of NLRP3 in the control mice, IcH mice, and IcH mice treated with pioglitazone (A). The expression level of NLRP3 in the IcH mice treated with pioglitazone was decreased more than those in the IcH mice on day 7 (B). ^*p<0.05. IcH : intracranial hemorrhage.

Fig. 5.

Liquid chromatography-tandem mass spectrometry analysis. In the glycolysis pathway, the production of glucose-6-phosphate, fructose-1,6- biphosphate, pyruvate, and lactate were increased in IcH mice brains treated with pioglitazone compared to those IcH mice (A). In the TcA cycle, the production of nicotinamide adenine dinucleotide was decreased in IcH mice treated with pioglitazone more than that of IcH mice. Differences in other metabolites were not noted (B). In the PPP, there were no significant differences in PPP metabolites between the two groups (c). ^*p<0.05. IcH : intracranial hemorrhage, TcA : tricarboxylic acid, PPP : pentose phosphate pathway