Blood flow analysis of compressed nerve root after intravenous injection of lipo-prostaglandin E1

Prostaglandin E1 Treatment for Lumbar Spinal Canal Stenosis: Review of the Literature

BACKGROUND

The important pathophysiologic factor of neurogenic intermittent claudication (NIC) in lumbar spinal canal stenosis (LSCS) has been reported to be the reduction in intraneural blood flow and a state of relative ischemia in nerve tissues. Prostaglandin E1 (PGE1) presumably improves symptoms in patients with LSCS by improving the blood flow in the cauda equina and nerve roots through its vasodilation and antiplatelet aggregation effects. The purpose of the study was to summarize the results of previous studies regarding PGE1 treatment for LSCS and to describe the details of PGE1 treatment to all physicians who take care of patients with LSCS.

METHODS

Review of the literature.

RESULTS

There are 3 PGE1-related products that have been used clinically for the treatment of LSCS: PGE1, lipo-PGE1, and limaprost (PGE1 derivative). Experimental studies have been performed to verify the efficacy of PGE1 treatment for LSCS. Many studies have reported clinical outcomes of PGE1 treatment in patients with LSCS. Overall, previous studies examining PGE1 treatment for LSCS demonstrate improvement in several clinical outcome measures such as the visual analog scale, Japanese Orthopaedic Association score, and NIC distance, although most of the studies have only short-term follow-up.

CONCLUSIONS

Based on the results of previous studies, PGE1 treatment may be an option as a conservative treatment for LSCS. However, future studies with high-quality and long-term follow-up are necessary. Future studies also should include refinement of indications, administration period, as well as comparisons between PGE1 treatment and other conservative treatments such as epidural injection.

Pathophysiology, diagnosis and treatment of intermittent claudication in patients with lumbar canal stenosis

Spinal nerve roots have a peculiar structure, different from the arrangements in the peripheral nerve. The nerve roots are devoid of lymphatic vessels but are immersed in the cerebrospinal fluid (CSF) within the subarachnoid space. The blood supply of nerve roots depends on the blood flow from both peripheral direction (ascending) and the spinal cord direction (descending). There is no hypovascular region in the nerve root, although there exists a so-called water-shed of the bloodstream in the radicular artery itself. Increased mechanical compression promotes the disturbance of CSF flow, circulatory disturbance starting from the venous congestion and intraradicular edema formation resulting from the breakdown of the blood-nerve barrier. Although this edema may diffuse into CSF when the subarachnoid space is preserved, the endoneurial fluid pressure may increase when the area is closed by increased compression. On the other hand, the nerve root tissue has already degenerated under the compression and the numerous macrophages releasing various chemical mediators, aggravating radicular symptoms that appear in the area of Wallerian degeneration. Prostaglandin E1 (PGE1) is a potent vasodilator as well as an inhibitor of platelet aggregation and has therefore attracted interest as a therapeutic drug for lumbar canal stenosis. However, investigations in the clinical setting have shown that PGE1 is effective in some patients but not in others, although the reason for this is unclear.

Co-administration of prostaglandin E1 with somatostatin attenuates acute liver damage after massive hepatectomy in rats via inhibition of inflammatory responses, apoptosis and endoplasmic reticulum stress

Acute liver damage is considered to be the major cause of mortality after massive hepatectomy. Prostaglandin E1 (PGE1) and somatostatin (SST) have been shown to protect against hepatic injury of rats after partial hepatectomy. However, the precise mechanisms remain largely unknown. In this study, we examined the effects of PGE1, SST and the combination of these two drugs on acute liver damage of rats after 90% hepatectomy. We found that animal survival was improved when pretreated with PGE1 and SST. Portal venous pressure (PVP), serum alanine aminotransferase (ALT) and aspartate aminotransaminase (AST), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were all reduced after administration of PGE1 and SST. In addition, apoptosis was inhibited via upregulation of Bcl-2 and downregulation of Bax and caspase-3 in drug treatment groups. Furthermore, pretreatment with PGE1 and SST alleviated endoplasmic reticulum (ER) stress by induction of heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78), but suppression of transcription factor C/EBP homologous protein (CHOP). Our data suggest that administration of PGE1 and SST, particularly in combination, may prevent acute liver damage of rats after massive hepatectomy by inhibiting inflammatory responses, apoptosis and ER stress.

S-Nitrosoglutathione administration ameliorates cauda equina compression injury in rats

Lumbar spinal stenosis (LSS) causes ischemia, inflammation, demyelination and results in dysfunction of the cauda equina (CE), leading to pain and locomotor functional deficits. We investigated whether exogenous administration of S-nitrosoglutathione (GSNO), an endogenous redox modulating anti-neuroinflammatory agent, hastens functional recovery in a CE compression (CEC) rat model. CEC was induced in adult female rats by the surgical implantation of two silicone blocks within the epidural spaces of L4-L6 vertebrae. GSNO (50 μg/kg body weight) was administered by gavage 1 h after the injury, and the treatment was continued daily thereafter. GSNO induced change in the pain threshold was evaluated for four days after the compression. Tissue analyses and locomotor function evaluation were carried out at two weeks and four weeks after the CEC respectively. GSNO significantly improved motor function in CEC rats as evidenced by an increased latency on rotarod compared with vehicle-treated CEC rats. CEC induced hyperalgesia was decreased by GSNO. GSNO also increased the expression of VEGF, reduced cellular infiltration (H&E staining) and apoptotic cell death (TUNEL assay), and hampered demyelination (LFB staining and g-ratio). These data demonstrate that administration of GSNO after CEC decreased inflammation, hyperalgesia and cell death leading to improved locomotor function of CEC rats. The therapeutic potential of GSNO observed in the present study with CEC rats suggests that GSNO is a candidate drug to test in LSS patients.