Protection of the rat brain from hypothermic circulatory arrest injury by a chipmunk protein

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Inhibition of long noncoding RNA growth arrest–specific 5 attenuates cerebral injury induced by deep hypothermic circulatory arrest in rats

OBJECTIVE

We sought to investigate cerebroprotection by targeting long noncoding RNA growth arrest-specific 5 in a rat model of prolonged deep hypothermic circulatory arrest.

METHODS

Deep hypothermic circulatory arrest was conducted for 60 minutes when the pericranial temperature was cooled to 18°C in rats. Dual luciferase assay was used to detect the binding relationship between growth arrest-specific 5 and putative target microRNAs. Adeno-associated viral vectors containing growth arrest-specific 5 small interfering RNA or negative control small interfering RNA were administered by intracerebroventricular injection 14 days before deep hypothermic circulatory arrest. Expressions of growth arrest-specific 5, microRNA-23a, phosphate and tension homology, Bcl-2-associated X protein, Bcl-2, phospho-protein kinase B, protein kinase B, and cleaved caspase-3 in the hippocampus were measured by quantitative reverse transcription polymerase chain reaction and Western blot. Spatial learning and memory functions were evaluated by the Morris water maze test. The hippocampus was harvested for histologic examinations and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling staining.

RESULTS

Luciferase assay showed that growth arrest-specific 5 targeted and inhibited microRNA-23a expression. After deep hypothermic circulatory arrest, hippocampal growth arrest-specific 5 expression was significantly enhanced with a robust decrease of hippocampal microRNA-23a expression. Small interfering RNA growth arrest-specific 5 significantly inhibited growth arrest-specific 5 expression and enhanced microRNA-23a expression in the hippocampus, accompanied with decreases of phosphate and tension homology and Bcl-2-associated X protein expression, and increases of Bcl-2 expression and phospho-protein kinase B/protein kinase B ratio. Growth arrest-specific 5 knockdown inhibited neuronal apoptosis, attenuated histologic damages, and increased the number of surviving neurons in the hippocampus. Spatial learning and memory functions after deep hypothermic circulatory arrest were also markedly improved by growth arrest-specific 5 inhibition.

CONCLUSIONS

Inhibition of large noncoding RNA growth arrest-specific 5 can provide a powerful cerebroprotection against deep hypothermic circulatory arrest, which may be mediated through microRNA-23a/phosphate and tension homology pathway.

A novel target to reduce microglial inflammation and neuronal damage after deep hypothermic circulatory arrest

BACKGROUND

Neuroinflammation acts as a contributor to neurologic deficits after deep hypothermic circulatory arrest. However, the molecular mechanism remains unclear. This study postulates that cold-inducible RNA-binding protein can promote deep hypothermic circulatory arrest-induced neuroinflammation.

METHODS

Rats were randomly assigned into 3 groups (n = 5, each group): sham group, deep hypothermic circulatory arrest group, and deep hypothermic circulatory arrest + Cirp^-/- group (Cirp^-/- group). Murine microglial BV2 cells were administered by adeno-associated viral vectors containing cold-inducible RNA-binding protein small interference RNA or negative control small interference RNA at 2 days before 4-hour oxygen-glucose deprivation at 18°C. Microglial activation, cell death, neuroinflammation, and related protein expression were assessed in tissue samples and cell cultures.

RESULTS

Cold-inducible RNA-binding protein was elevated along with evident neuroinflammation and neuronal damage in rats exposed to deep hypothermic circulatory arrest. In Cirp^-/- rats, histologic injury (3.00 [interquartile range, 2.00-3.00] vs 1.00 [interquartile range, 1.00-1.50] neuropathological score, P < .001) and microglial activation (40 ± 4 vs 13 ± 7 CA1 area, P < .001) were alleviated after deep hypothermic circulatory arrest. With RNA-sequencing analysis, this associated with reduction of key proinflammatory cytokines induced by inhibiting Brd2-NF-κB signals. In BV2 cells treated with small interference RNA-cold-inducible RNA-binding protein, similar protective effects were observed, including decreased proinflammatory cytokines and cytotoxicity. Brd2-NF-κB signals were confirmed by the addition of Brd2 inhibitor JQ1. Notably, the conditioned medium from BV2 cells transfected with small interference RNA cold-inducible RNA-binding protein significantly reduced apoptosis in neural SH-SY5Y cells after oxygen-glucose deprivation, which was similar to that after JQ1 administration.

CONCLUSIONS

Enhanced cold-inducible RNA-binding protein in microglia aggravates neuronal injury by promoting the release of proinflammatory cytokines, which might be mediated through Brd2-NF-κB signals during deep hypothermic circulatory arrest.