title: Rats with minimal hepatic encephalopathy show reduced cGMP-dependent protein kinase activity in hypothalamus correlating with circadian rhythms alterations.
abstract: Patients with liver cirrhosis show disturbances in sleep and in its circadian rhythms which are an early sign of minimal hepatic encephalopathy (MHE). The mechanisms of these disturbances are poorly understood. Rats with porta-caval shunt (PCS), a model of MHE, show sleep disturbances reproducing those of cirrhotic patients. The aims of this work were to characterize the alterations in circadian rhythms in PCS rats and analyze the underlying mechanisms. To reach these aims, we analyzed in control and PCS rats: (a) daily rhythms of spontaneous and rewarding activity and of temperature, (b) timing of the onset of activity following turning-off the light, (c) synchronization to light after a phase advance and (d) the molecular mechanisms contributing to these alterations in circadian rhythms. PCS rats show altered circadian rhythms of spontaneous and rewarding activities (wheel running). PCS rats show more rest bouts during the active phase, more errors in the onset of motor activity and need less time to re-synchronize after a phase advance than control rats. Circadian rhythm of body temperature is also slightly altered in PCS rats. The internal period length (tau) of circadian rhythm of motor activity is longer in PCS rats. We analyzed some mechanisms by which hypothalamus modulate circadian rhythms. PCS rats show increased content of cGMP in hypothalamus while the activity of cGMP-dependent protein kinase was reduced by 41% compared to control rats. Altered cGMP-PKG pathway in hypothalamus would contribute to altered circadian rhythms and synchronization to light.
authors.affiliation: a Laboratory of Neurobiology , Centro de Investigación Príncipe Felipe, Eduardo Primo Yúfera , Valencia , Spain .
authors.forename: Vicente
authors.initials: V
authors.lastname: Felipo
authors.forename: Blanca
authors.initials: B
authors.lastname: Piedrafita
authors.forename: Juan A
authors.initials: JA
authors.lastname: Barios
authors.forename: Ana
authors.initials: A
authors.lastname: Agustí
authors.forename: Hanan
authors.initials: H
authors.lastname: Ahabrach
authors.forename: María
authors.initials: M
authors.lastname: Romero-Vives
authors.forename: Luis C
authors.initials: LC
authors.lastname: Barrio
authors.forename: Beatriz
authors.initials: B
authors.lastname: Rey
authors.forename: Jose M
authors.initials: JM
authors.lastname: Gaztelu
authors.forename: Marta
authors.initials: M
authors.lastname: Llansola
mesh_terms: D000204:Activity Cycles; D000818:Animals; D001522:Behavior, Animal; D001833:Body Temperature Regulation; D021081:Chronobiology Disorders / Q000201:enzymology* / Q000209:etiology / Q000503:physiopathology / Q000523:psychology; D002940:Circadian Rhythm; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D004195:Disease Models, Animal; D015536:Down-Regulation; D006501:Hepatic Encephalopathy / Q000201:enzymology* / Q000209:etiology / Q000503:physiopathology / Q000523:psychology; D007031:Hypothalamus / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D009043:Motor Activity; D017440:Photoperiod; D011167:Portacaval Shunt, Surgical; D017208:Rats, Wistar; D012420:Running; D012890:Sleep; D013997:Time Factors
chemical_list: D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP
keywords: Cyclic GMP; electroencephalogram; hypothalamus; light synchronization; porta-caval anastomosis; sleep–wake cycle