As mentioned above, one of the main endogenous opioids with increased production following low dose naltrexone is met-enkephalin (also known as methionine enkephalin, and as opioid growth factor). A Chinese study published online in August 2016 examined the effects of met-enkephalin on microglial cells in culture . As explained in this study and elsewhere, microglia (the resident macrophages of the nervous system) and macrophages infiltrating from the systemic circulation are actively recruited into tumors, polarized to a tumor-promoting M2 phenotype and away from a tumor-fighting M1 phenotype, and can make up as much as 30% of a GBM tumor. The investigators found that at the optimal concentration of met-enkephalin (1 picomolar), M1-type cytokine production and surface proteins were increased in the microglia, including interleukin-12, TNF-alpha, CD86, CD40, and iNOS. In contrast, M2 cytokines and markers were not affected, including interleukin-10, TGF-beta, CD163, and arginase. Phagocytosis (a main function of M1 macrophages) and cytotoxicity towards U87 glioblastoma cells was increased by met-enkephalin treatment. Thus, met-enkephalin (opioid growth factor), an endogenous opioid whose production is increased in humans following transient opioid receptor blockade by low dose naltrexone, may aid glioma patients by reverting tumor-associated microglia to an M1 anti-tumor phenotype.
View common questions and answers about the use of low dose naltrexone at LDN Science. Especially interesting areinterviews with Dr. Ian Zagon, who discovered the clinical benefits of naltrexone in very low doses.
The effective dose of low dose naltrexone ranges from 2.5 – 10 mg, with the most common dose being 4.5 mg daily. LDN may be taken in the morning or evening. Some individuals may experience sleep disturbances (such as nightmares) caused by LDN and these people may choose to take their daily dose in the morning.