title: Effect of aging on 24-hour changes in dopamine and serotonin turnover and amino acid and somatostatin contents of rat corpus striatum.
abstract: This study examined the 24-hour changes in a number of transmitters in the corpus striatum of young and middle-aged male Wistar rats. The contents of excitatory amino acids (glutamate, aspartate) and inhibitory amino acids (gamma-aminobutyric acid, GABA; taurine, glycine) and of somatostatin were measured in 2-month- and 18- to 20-month-old rats killed at six different time points along the 24-hour cycle. The striatal serotonin and dopamine turnover was also measured. Both young and middle-aged rats showed significant 24-hour variations in striatal glutamate and aspartate contents; only in young rats these variations fitted a cosine function, with acrophase during the first part of rest span. Mesor values of striatal excitatory amino acid contents were lowest in middle-aged rats. Significant 24-hour variations in striatal contents of GABA, taurine, and glycine occurred in young rats, while only striatal GABA exhibited 24-hour changes in middle- aged rats (acrophases during the first part of rest span). For every inhibitory transmitter, the mesor values in middle-aged rats were significantly lower than in young rats. The 24-hour variation of the striatal somatostatin content showed acrophase during the first part of rest span, mesor values and amplitude being lowest in middle-aged rats. Aging rats exhibited significantly higher mesor values of striatal serotonin turnover (34% increase) and lower mesor values of dopamine turnover (69% decrease) than their younger counterparts. Some of the circadian modifications of motor function seen in aging rats could be related to the striatal transmitter changes reported herein.
authors.affiliation: Departamento de Bioquímica y Biología Molecular III, Facultad de Medicina, Universidad Complutense, Madrid, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Esquifino
authors.forename: Pilar
authors.initials: P
authors.lastname: Cano
authors.forename: Fernando
authors.initials: F
authors.lastname: Chacon
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Reyes Toso
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Cardinali
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D009069:Movement Disorders / Q000378:metabolism / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D013004:Somatostatin / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: D018377:Neurotransmitter Agents; D012701:Serotonin; D013004:Somatostatin; D004298:Dopamine