الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Serotonin is known as a neurotransmitter that modulates neural signaling in a wide range of neuropsychological activities it plays a critical role in a wide variety of physiological and behavioral processes, In the circulation it act as a neurotransmitter in the central nervous system or as paracrine factor in the gastrointestinal tract which is the largest source of serotonin ,approximately 90% of total serotonin is found there and is synthesized mainly in the enterochromaffin cells serotonin is formed in the body from exogenous L-tryptophan. It have seven families of receptors comprising a total of 14 subtypes. platelets is major site for storage of serotonin that release it at sit of injury and The liver is an important site of serotonin metabolism. in the liver serotonin plays a crucial role in regulating hepatic function and response to injury.It is act as a neurotransmitter and as a neuroendocrine hormone. It regulates ANS input to the liver, blood flow within the normal and healthy liver and also regulates the proliferation and function of a number of key resident liver cells. Serotonin play vital role in liver regeneration it has recently shown that platelet-derived serotonin is involved in the initiation of liver regeneration and serotonin antagonist can arrest the liver regeneration after partial hepatectomy in rats as serotonin is involved in the induction of hepatocyte DNA synthesis. Additionally, there is evidence that serotonin also play a role in liver regeneration at the cerebral level. platelets are critical for liver regeneration after hepatectomy. In humans there is an interconnection between serotonin, liver and platelets. There fore after splenectomy there is, an increases in platelete count with subsequent acceleration of liver regeneration. In thrompocytopnia there is delaing in liver regeneration. Also serotonin appears like a double-edged sword for the liver - aiding its repair but also promoting liver diseases and tumors. Serotonin is involved in many pathological conditions of the liver such as; steatohepatitis , aggravation of viral hepatitis and development of oesophegeal and gastric variceses ,further more , it plays a crucial role in the progression of hepatic fibrosis. Finally, serotonin facilitate tumor growth of primary liver carcinoma like cholangiocarcinoma and hepatocellular carcinoma. Therefore serotonin modulating drugs can find a place in the arm amentarium of hepatologists and liver surgeons. The use of selective serotonin reuptake inhibitor (SSRIs) and/or serotonin receptor agonists/antagonists has been a successful treatment for a number of conditions, illustrating that serotonin can modulate a range of functions in multiple system. Potent and selective antagonists of 5-HT2B are already available and have been reported as being safe for clinical use in humans. Potent and selective antagonists of 5-HT2B are already available and have been reported as being safe for clinical use in humans. This class of drug may have therapeutic potential in liver disease, both as stimulants of hepatocyte regeneration and as anti-fibrotic agents so serotonin will be an excellent candidate for fututer researchs.