Changes in high K+-evoked serotonin release and serotonin 2A/2C receptor binding in the frontal cortex of rats with thioacetamide-induced hepatic encephalopathy.
Serotonergic systems were investigated in the frontal cortex of rats with thioacetamide (TAA)-induced acute hepatic encephalopathy (HE). Extracellular basal levels of 5-HT showed no difference between control and HE animals, whereas the levels of 5-HIAA were significantly increased in HE rats. Unlike basal levels, high K+-evoked 5-HT release was significantly higher in HE rats than controls. Bmax of (+/-)-1-(2,5-dimethoxy-4-[125I] iodophenyl)-2-aminopropane ([125I] DOI) binding, mainly labeling postsynaptic 5-HT2A receptors, was significantly decreased without any change in Kd in HE rats. These results suggest that there is no change in basal 5-HT release in the cortex of rats with TAA-induced HE despite the increase in intraneuronal 5-HT metabolism and in the size of releasable 5-HT pool, and that serotonergic neurotransmission via 5-HT2A receptor is altered in the brain area of rats with HE.
Kaneko
K
K
Department of Neuropsychiatry, Tokyo Medical and Dental University School of Medicine, Japan.
Kurumaji
A
A
Watanabe
A
A
Yamada
S
S
Toru
M
M
D000208:Acute Disease; D000662:Amphetamines / Q000378:metabolism; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005110:Extracellular Space / Q000378:metabolism; D005625:Frontal Lobe / Q000378:metabolism* / Q000648:ultrastructure; D006501:Hepatic Encephalopathy / Q000139:chemically induced / Q000378:metabolism*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044402:Receptor, Serotonin, 5-HT2A; D044405:Receptor, Serotonin, 5-HT2C; D011985:Receptors, Serotonin / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000378:metabolism; D013569:Synapses / Q000378:metabolism; D013853:Thioacetamide / Q000633:toxicity; D014364:Tryptophan / Q000378:metabolism
D000662:Amphetamines; D044402:Receptor, Serotonin, 5-HT2A; D044405:Receptor, Serotonin, 5-HT2C; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D013853:Thioacetamide; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine; D011188:Potassium