Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6264943 | Brain Research | 2011 | 11 Pages |
Endogenous opioids inhibit the onset and progression of experimental autoimmune encephalomyelitis (EAE) with 30Â days of treatment. This study examined the long term effects of the opioid growth factor (OGF, [Met5]-enkephalin) and a low dose of the opioid antagonist naltrexone (LDN) on expression of myelin oligodendrocyte glycoprotein (MOG)-induced EAE. C57BL/6 mice began receiving daily injections of 10Â mg/kg OGF (MOGÂ +Â OGF), 0.1Â mg/kg naltrexone (MOGÂ +Â LDN), or saline (MOGÂ +Â Vehicle) at the time of EAE induction and continuing for 60Â days. In contrast to 100% of the MOGÂ +Â Vehicle group with behavioral symptoms of EAE, 63% and 68% of the MOGÂ +Â OGF and MOGÂ +Â LDN mice expressed disease. Both severity and disease indices of EAE in OGF- and LDN-treated mice were notably decreased from MOGÂ +Â Vehicle cohorts. By day 60, 6- and 3-fold more animals in the MOGÂ +Â OGF and MOGÂ +Â LDN groups, respectively, had a remission compared to MOGÂ +Â Vehicle mice. Neuropathological studies revealed i) astrocyte activation and neuronal damage as early as day 10 (prior to behavioral symptoms) in all MOG-injected groups, ii) a significant reduction of activated astrocytes in MOGÂ +Â OGF and MOGÂ +Â LDN groups compared to MOGÂ +Â Vehicle mice at day 30, and iii) no demyelination on day 60 in mice treated with OGF or LDN and not displaying disease symptoms. These results indicate that treatment with OGF or LDN had no deleterious long-term repercussions and did not exacerbate EAE, but i) halted progression of disease, ii) reversed neurological deficits, and iii) prevented the onset of neurological dysfunction across a considerable span of time.
Research Highlights⺠OGF and LDN have long-term effects on EAE. ⺠OGF and LDN prevent the onset of neurological behavioral symptoms of EAE. ⺠OGF and LDN can halt the expression of EAE. ⺠OGF and LDN can reverse neurological deficits of EAE. ⺠OGF and LDN may be utilized in translational studies for multiple sclerosis.