Meglumine cyclic adenylate improves neurological function following acute spinal cord injury in rats

Meglumine cyclic adenylate improves cardiovascular hemodynamics and motor-function in a rat model of acute T4 thoracic spinal cord injury

STUDY DESIGN

Animal experimental study.

OBJECTIVES

Spinal cord injury (SCI) at or above the T6 level causes cardiovascular dysfunction. Maintaining cAMP levels with cAMP analogs can facilitate neurological recovery. In the present study, the effects of meglumine cyclic adenylate (MCA), a cAMP analog and approved cardiovascular drug, on cardiovascular and neurological recovery in acute T4-SCI in rats were investigated.

SETTING

Hospital in Kunming, China.

METHODS

Eighty rats were randomly allocated to five groups, and groups A-D received SCI: (A) a group administered MCA at 2 mg/kg/d iv qd, (B) a group administered dopamine at 2.5 to 5 μg/kg/min iv to maintain mean arterial pressure above 85 mm Hg, (C) a group administered atropine at 1 mg/kg iv bid, (D) a group receiving an equal volume of saline iv qd for 3 weeks after SCI and (E) a group undergoing laminectomy only. The cardiovascular and behavioral parameters of the rats were examined, and spinal cord tissues were processed for hematoxylin and eosin staining, Nissl staining, electron microscopy, and analysis of cAMP levels.

RESULTS

Compared with dopamine or atropine, MCA significantly reversed the decrease in cAMP levels in both myocardial cells and the injured spinal cord; improved hypotension, bradycardia and behavioral parameters at 6 weeks; and improved spinal cord blood flow and histological structure at 7 days post-SCI. The regression analysis suggested spinal cord motor-function improved as decreased heart rate and mean arterial pressure were stopped post-SCI.

CONCLUSIONS

MCA may be an effective treatment for acute SCI by sustaining cAMP-dependent reparative processes and improving post-SCI cardiovascular dysfunction.

SPONSORSHIP

N/A.

Cyclic adenosine monophosphate in acute ischemic stroke: some to update, more to explore

The development of effective treatment for ischemic stroke, which is a common cause of morbidity and mortality worldwide, remains an unmet goal because the current first-line treatment management interventional therapy has a strict time window and serious complications. In recent years, a growing body of evidence has shown that the elevation of intracellular and extracellular cyclic adenosine monophosphate (cAMP) alleviates brain damage after ischemic stroke by attenuating neuroinflammation in the central nervous system and peripheral immune system. In the central nervous system, upregulated intracellular cAMP signaling can alleviate immune-mediated damage by restoring neuronal morphology and function, inhibiting microglia migration and activation, stabilizing the membrane potential of astrocytes and improving the cellular functions of endothelial cells and oligodendrocytes. Enhancement of the extracellular cAMP signaling pathway can improve neurological function by activating the cAMP-adenosine pathway to reduce immune-mediated damage. In the peripheral immune system, cAMP can act on various immune cells to suppress peripheral immune function, which can alleviate the inflammatory response in the central nervous system and improve the prognosis of acute cerebral ischemic injury. Therefore, cAMP may play key roles in reducing post-stroke neuroinflammatory damage. The protective roles of the cAMP indicate that the cAMP enhancing drugs such as cAMP supplements, phosphodiesterase inhibitors, adenylate cyclase agonists, which are currently used in the treatment of heart and lung diseases. They are potentially able to be applied as a new therapeutic strategy in ischemic stroke. This review focuses on the immune-regulating roles and the clinical implication of cAMP in acute ischemic stroke.

Overexpression of HIPK2 attenuates spinal cord injury in rats by modulating apoptosis, oxidative stress, and inflammation

HIPK2 is considered to be a tumor suppressor. It also has been implicated in several functions such as apoptosis and inflammation that are linked to spinal cord injury (SCI). However, whether HIPK2 ameliorates the neurological pain of SCI remains unclear. Here, we investigated the effects of HIPK2 on neurological function, oxidative stress, levels of inflammatory cytokines and expression of Bcl-2/Bax in an SCI model. Firstly, we evaluated the therapeutic effects of HIPK2 on neurological pain in the SCI rat using the Basso, Beattie and Bresnahan scores and H & E staining. Overexpression of HIPK2 significantly elevated the levels of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), and reduced the mRNA expression of Nogo-A and RhoA in SCI rats. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays showed that overexpression of HIPK2 significantly reduced the number of apoptotic cells. Overexpression of HIPK2 also decreased expression of Bax and Caspase-3 and elevated expression of Bcl-2 in the SCI model, indicating that HIPK2 exhibited its protective activity by inhibiting SCI-induced apoptosis. Then, we measured the serum concentrations of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX). We also determined the mRNA and protein levels of nuclear factor-κB p65 unit, tumor necrosis factor-α (TNF-α), and interleukin (IL)-1β. HIPK2 overexpression reduced oxidative stress and the levels of inflammatory cytokines compared with SCI control animals. Additionally, acetylation of HIPK2 was reduced in SCI rats. Overexpression of HIPK2 could enhance autophagy by elevating the expression of Beclin-1 and LC3-II while autophagy is regarded as a beneficial regulator to improve spinal cord injury. Together, overexpression of HIPK2 improved contusive SCI induced pain by modulating oxidative stress, Bcl‑2 and Bax signaling, and inflammation, and also regulating autophagy.