Inosine, an endogenous purine nucleoside, has immunomodulatory, neuroprotective, and analgesic properties. In vitro: Inosine has been shown to stimulate axonal growth in cell culture and promote corticospinal tract axons to sprout collateral branches after stroke, spinal cord injury and TBI in rodent models.[1] Inosine dose-dependently stimulates cAMP production mediated through the A2AR. Inosine dose-dependently induces A2AR-mediated ERK1/2 phosphorylation.[2] In vivo: The reference for Inosine is 1 or 10 mg/kg, i.p. Preventive treatment with inosine inhibits the development and progression of EAE in C57Bl/6 mice. neuroinflammation and demyelinating processes are blocked by inosine treatment. Additionally, inosine consistently inhibits IL-17 levels in peripheral lymphoid tissue, as well as IL-4 levels and A2AR up-regulation in the spinal cord, likely, through an ERK1-independent pathway. [3] inosine acting through adenosine receptors (ARs) exerts a wide range of anti-inflammatory and immunomodulatory effects in vivo. [2]

References:
[1]. Moore TL et al. Inosine enhances recovery of grasp following cortical injury to the primary motor cortex of the rhesus monkey. Restor Neurol Neurosci. 2016 Aug 1.
[2]. Welihinda AA et al. The adenosine metabolite inosine is a functional agonist of the adenosine A2A receptor with a unique signaling bias. Cell Signal. 2016 Jun;28(6):552-60.
[3]. Junqueira SC et al. Inosine, an Endogenous Purine Nucleoside, Suppresses Immune Responses and Protects Mice from Experimental Autoimmune Encephalomyelitis: a Role for A2A Adenosine Receptor. Mol Neurobiol. 2016 Apr 30.