Premium
Hyperammonaemia alters the mechanisms by which metabotropic glutamate receptors in nucleus accumbens modulate motor function
Author(s) -
Cauli Omar,
Mlili Nisrin,
Rodrigo Regina,
Felipo Vicente
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.04734.x
Subject(s) - nucleus accumbens , neuroscience , metabotropic glutamate receptor , glutamate receptor , metabotropic receptor , portacaval shunt , ventral pallidum , microdialysis , medicine , chemistry , endocrinology , dopamine , biology , basal ganglia , receptor , globus pallidus , central nervous system , cirrhosis , portal hypertension
Activation of metabotropic glutamate receptors by injecting ( S )3,5‐dihydroxyphenylglycine (DHPG) in nucleus accumbens (NAcc) increases motor activity by different mechanisms in control rats and in rats with chronic liver failure due to portacaval shunt. In control rats DHPG increases extracellular dopamine in NAcc and induces locomotion by activating the ‘normal’ circuit: NAcc→ventral pallidum→medial‐dorsal thalamus→prefrontal cortex, which is not activated in portacaval shunt rats. In these rats, DHPG activates an ‘alternative’ circuit: NAcc→substantia nigra pars reticulata→ventro‐medial thalamus→prefrontal cortex, which is not activated in control rats. The reasons by which liver failure leads to activation of this ‘alternative’ circuit remain unclear. The aim of this work was to assess whether hyperammonaemia could be responsible for the alterations found in chronic liver failure. We injected DHPG in NAcc of control or hyperammonaemic rats and analysed, by in vivo brain microdialysis, the neurochemical responses of the ‘normal’ and ‘alternative’ circuits. In hyperammonaemic rats DHPG injection in NAcc activates both the ‘normal’ and ‘alternative’ circuits. In hyperammonaemia, activation of the ‘alternative’ circuit and increased motor response following metabotropic glutamate receptors activation in NAcc seem due to an increase in extracellular glutamate which activates AMPA receptors.