What is the role of astrocyte function in the pathogenesis of hepatic encephalopathy (HE)?

Updated: Apr 04, 2019
  • Author: David C Wolf, MD, FACP, FACG, AGAF, FAASLD; Chief Editor: BS Anand, MD  more...
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Answer

A number of theories have been proposed to explain the development of hepatic encephalopathy in patients with cirrhosis. Some investigators contend that hepatic encephalopathy is a disorder of astrocyte function. Astrocytes account for about one third of the cortical volume. They play a key role in the regulation of the blood-brain barrier. They are involved in maintaining electrolyte homeostasis and in providing nutrients and neurotransmitter precursors to the neurons. They also play a role in the detoxification of a number of chemicals, including ammonia. [13]

It is theorized that neurotoxic substances, including ammonia and manganese, may gain entry into the brain in the setting of liver failure. These neurotoxic substances may then contribute to morphologic changes in the astrocytes. In cirrhosis, astrocytes may undergo Alzheimer type II astrocytosis. Here, astrocytes become swollen. They may develop a large pale nucleus, a prominent nucleolus, and margination of chromatin. In ALF, astrocytes may also become swollen. The other changes of Alzheimer type II astrocytosis are not seen in ALF. But, in contrast to cirrhosis, astrocyte swelling in ALF may be so marked as to produce brain edema. This may lead to increased intracranial pressure and, potentially, brain herniation.


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