Traumatic brain injury (TBI) and comorbid alcohol use disorder (AUD) cause heavy medical, economic, and social burdens. TBI drives the escalation of alcohol intake in TBI patients and animal models. One challenge is that TBI and comorbid AUD (alcohol misuse following TBI) is difficult to manage with current treatment options. Another challenge is that the molecular mechanisms underlying alcohol misuse following TBI are lacking. Thus, it is urgently needed to explore novel therapies and molecular mechanisms for AUD following TBI. We and others reported that N-acetyl-serotonin (NAS) offers protection by targeting neurotoxicity and inflammation in various tissue injuries. However, it is unknown whether NAS alleviates AUD following TBI. The central hypothesis of this translational project is that NAS mitigates TBI-induced alcohol consumption. The overall goal is to develop a novel NAS therapy to alleviate TBI-increased alcohol intake and preference and elucidate its protective mechanisms by regulating brain-derived neurotrophic factor (BDNF), tyrosine receptor kinase B (TrkB)/Akt pathway, and inflammation. This study is supported by preliminary data and prior research: 1) NAS is a potent agonist of TrkB, and the BDNF/TrkB pathway plays an important role in alcohol consumption. 2) we and others report that NAS inhibits neurotoxicity in cultured neurons and offers protection in animal models of cerebral ischemia and retinal ischemia-reperfusion. 3) we and others reported that NAS protects hepatic cell apoptosis and hepatic ischemia-reperfusion injury and acts on circadian rhythm by TrkB activation. 4) our preliminary data suggest that NAS alleviates TBI-induced alcohol intake and preference, cognitive decline, and neurobehavioral deficit in a few mice in vivo and prevents neurotoxicity in scratch- and ethanol-treated cultured neuronal cells, a cell injury model of alcohol use following TBI in vitro. 5) we show that NAS reduces interleukin-1β (IL-1 and IL- 6 releases in scratch- and ethanol-treated astrocytes, another cell injury model of alcohol use following TBI, and 6) we found that NAS alleviates BDNF reduction in TBI-induced alcohol consumption exposed mice. Aim 1 will test whether NAS alleviates TBI-induced alcohol consumption, neurodegeneration, and cognitive and neurobehavioral impairments in mice and determine whether TrkB deficiency, at least partly, reduces NAS’s benefits in TrkB knockout mice. Aim 2 will determine whether the protective mechanisms of NAS are mediated by regulating BDNF expression, activating TrkB/Akt pathway, and inhibiting inflammation as well as the regulation of BDNF/TrkB/Akt pathway of NAS are mediated by activation of TrkB using TrkB knockout mice. The success of this study will make an important contribution to drug discovery and pathogenesis for alcohol misuse following TBI. Key strengths include: i) Usage of TBI, AUD, and TBI-induced alcohol intake and preference animal models; ii) Extensive experience in the stu...