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Motor activity is modulated via different neuronal circuits in rats with chronic liver failure than in normal rats
Author(s) -
Cauli Omar,
Mlili Nisrin,
Llansola Marta,
Felipo Vicente
Publication year - 2007
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2007.05435.x
Subject(s) - nucleus accumbens , neuroscience , ventral pallidum , basal ganglia , dopamine , microdialysis , glutamate receptor , premovement neuronal activity , direct pathway of movement , chemistry , medicine , globus pallidus , biology , central nervous system , receptor
The mechanisms by which liver failure alters motor function remain unclear. It has been suggested that liver disease alters the neuronal circuit between basal ganglia and cortex that modulates motor function. Activation of group I metabotropic glutamate receptors in the nucleus accumbens (NAcc) by injecting (S)‐3,5‐dihydroxyphenylglycine (DHPG) activates this circuit and induces locomotion We analysed by in vivo brain microdialysis the function of the circuits that modulate motor function in rats with liver failure due to portacaval shunt (PCS). We inserted cannulae in the NAcc and microdialysis probes in the NAcc, ventral pallidum (VP), substantia nigra pars reticulata (SNr), medio‐dorsal thalamus (MDT), ventro‐medial thalamus (VMT) or prefrontal cortex (PFCx). We injected DHPG in the NAcc and analysed extracellular neurotransmitters concentration in these areas. The results indicate that in control rats DHPG induces locomotion by activating the ‘normal’ neuronal circuit: NAcc → VP → MDT → PFCx. In PCS rats this circuit is not activated. In PCS rats, DHPG injection activates an ‘alternative’ circuit: NAcc → SNr → VMT → PFCx. This circuit is not activated in control rats. DHPG injection increases dopamine in the NAcc of control but not of PCS rats, and glutamate in PCS but not in control rats. DHPG‐induced increase in dopamine would activate the ‘normal’ neuronal circuit, while an increase in glutamate would activate the ‘alternative’ circuit. The identification of the mechanisms responsible for altered motor function and coordination in liver disease would allow designing treatments to improve motor function in patients with hepatic encephalopathy.