Activation of TGR5 with INT-777 attenuates oxidative stress and neuronal apoptosis via cAMP/PKCε/ALDH2 pathway after subarachnoid hemorrhage in rats

Gang Zuo; Tongyu Zhang; Lei Huang; Camila Araujo; Jun Peng; Zachary Travis; Takeshi Okada; Umut Ocak; Guangyu Zhang; Jiping Tang; Xiaojun Lu; John H Zhang

doi:10.1016/j.freeradbiomed.2019.09.002

Activation of TGR5 with INT-777 attenuates oxidative stress and neuronal apoptosis via cAMP/PKCε/ALDH2 pathway after subarachnoid hemorrhage in rats

Free Radic Biol Med. 2019 Nov 1:143:441-453. doi: 10.1016/j.freeradbiomed.2019.09.002. Epub 2019 Sep 4.

Authors

Gang Zuo¹, Tongyu Zhang², Lei Huang³, Camila Araujo⁴, Jun Peng⁴, Zachary Travis⁴, Takeshi Okada⁴, Umut Ocak⁴, Guangyu Zhang⁵, Jiping Tang⁴, Xiaojun Lu⁶, John H Zhang⁷

Affiliations

¹ Department of Neurosurgery, The Affiliated Taicang Hospital, Soochow University, Taicang, Suzhou, Jiangsu, 215400, China; Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA.
² Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA; Department of Neurosurgery, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, 150001, China.
³ Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA; Department of Neurosurgery, Loma Linda University, Loma Linda, CA, 92350, USA.
⁴ Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA.
⁵ Mass Spectrometry Core Facility, Loma Linda University, Loma Linda, CA, 92350, USA.
⁶ Department of Neurosurgery, The Affiliated Taicang Hospital, Soochow University, Taicang, Suzhou, Jiangsu, 215400, China. Electronic address: luxiaojun5215@163.com.
⁷ Department of Physiology and Pharmacology, Loma Linda University, Loma Linda, CA, 92350, USA; Department of Neurosurgery, Loma Linda University, Loma Linda, CA, 92350, USA; Department of Anesthesiology, Loma Linda University, Loma Linda, CA, 92350, USA. Electronic address: jhzhang@llu.edu.

PMID: 31493504
PMCID: PMC6848789
DOI: 10.1016/j.freeradbiomed.2019.09.002

Abstract

Background: Oxidative stress and neuronal apoptosis play important roles in the pathogenesis of early brain injury (EBI) after subarachnoid hemorrhage (SAH). The activation of TGR5, a novel membrane-bound bile acid receptor, possesses anti-oxidative stress and anti-apoptotic effects in hepatobiliary disease and kidney disease. The present study aimed to explore the neuroprotective effect of TGR5 activation against EBI after SAH and the potential underlying mechanisms.

Methods: The endovascular perforation model of SAH was performed on 199 Sprague Dawley rats to investigate the beneficial effects of TGR5 activation after SAH. INT-777, a specific synthetic TGR5 agonist, was administered intranasally at 1 h after SAH induction. TGR5 CRISPR and ALDH2 CRISPR were administered intracerebroventricularly at 48 h before SAH to illuminate potential mechanisms. The SAH grade, short-term and long-term neurobehavioral tests, TUNEL staining, Fluoro-Jade C staining, Nissl staining, immunofluorescence staining, and western blots were performed at 24 h after SAH.

Results: The expressions of endogenous TGR5 and ALDH2 gradually increased and peaked at 24 h after SAH. TGR5 was expressed primarily in neurons, as well as in astrocytes and microglia. The activation of TGR5 with INT-777 significantly improved the short-term and long-term neurological deficits, accompanied by reduced the oxidative stress and neuronal apoptosis at 24 h after SAH. Moreover, INT-777 treatment significantly increased the expressions of TGR5, cAMP, phosphorylated PKCε, ALDH2, HO-1, and Bcl-2, while downregulated the expressions of 4-HNE, Bax, and Cleaved Caspase-3. TGR5 CRISPR and ALDH2 CRISPR abolished the neuroprotective effects of TGR5 activation after SAH.

Conclusions: In summary, the activation of TGR5 with INT-777 attenuated oxidative stress and neuronal apoptosis via the cAMP/PKCε/ALDH2 signaling pathway after SAH in rats. Furthermore, TGR5 may serve as a novel therapeutic target to ameliorate EBI after SAH.

Keywords: ALDH2; Early brain injury; INT-777; Neuronal apoptosis; Oxidative stress; Subarachnoid hemorrhage; TGR5.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Aldehyde Dehydrogenase, Mitochondrial / genetics
Aldehyde Dehydrogenase, Mitochondrial / metabolism
Animals
Brain Injuries / drug therapy*
Brain Injuries / metabolism
Brain Injuries / pathology
Cholic Acids / pharmacology*
Cyclic AMP / metabolism
Gene Expression Regulation / drug effects*
Male
Neurons / drug effects*
Neurons / pathology
Neuroprotective Agents
Oxidative Stress / drug effects*
Phosphorylation
Protein Kinase C-epsilon / genetics
Protein Kinase C-epsilon / metabolism
Rats
Rats, Sprague-Dawley
Receptors, G-Protein-Coupled / genetics
Receptors, G-Protein-Coupled / metabolism*
Signal Transduction
Subarachnoid Hemorrhage / complications*

Substances

6alpha-ethyl-23(S)-methylcholic acid
Cholic Acids
Gpbar1 protein, rat
Neuroprotective Agents
Receptors, G-Protein-Coupled
Cyclic AMP
Aldehyde Dehydrogenase, Mitochondrial
Aldh2 protein, rat
Protein Kinase C-epsilon

Abstract

Publication types

MeSH terms

Substances

Grants and funding