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.
Gang Zuo  1 ,  Tongyu Zhang  2 ,  Lei Huang  3 ,  Camila Araujo  4 ,  Jun Peng  4 ,  Zachary Travis  4 ,  Takeshi Okada  4 ,  Umut Ocak  4 ,  Guangyu Zhang  5 ,  Jiping Tang  4 ,  Xiaojun Lu  6 ,  John H Zhang  7
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: [email protected].
  • 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: [email protected].
PMID: 31493504 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.
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