Affiliation:
1. Department of Radiology First Affiliated Hospital of Soochow University Suzhou Jiangsu People's Republic of China
2. Center for Circadian Clocks Soochow University Suzhou People's Republic of China
3. Department of Urology First Affiliated Hospital of Soochow University Suzhou Jiangsu People's Republic of China
4. Suzhou Medical College of Soochow University Suzhou Jiangsu People's Republic of China
5. Philips Healthcare Shanghai People's Republic of China
6. Department of Traditional Chinese Medicine First Affiliated Hospital of Soochow University Suzhou People's Republic of China
Abstract
BackgroundThe changes that occur in the gamma‐aminobutyric acid (GABA) levels within specific brain regions throughout the day are less clear.PurposeTo evaluate the daily fluctuations of GABA levels within the parietal lobe (PL) and anterior cingulate gyrus (ACC) regions and explore their association with melatonin (MT) levels, heart rate (HR), and blood pressure.Study TypeProspective.Subjects26 healthy young adults (15 males and 11 females aged 22–27 years).Field Strength/Sequence3.0T, T1‐weighted imaging, Mescher–Garwood point resolved spectroscopy (MEGA‐PRESS) sequence.AssessmentThe acquired GABA signal contained the overlapping signals of macromolecules and homocarnosine, hence expressed as GABA+. The creatine (Cr) signal was applied as an endogenous reference. The GABA+, GABA+/Cr were measured at six different time points (1:00, 5:00, 9:00, 13:00, 17:00, and 21:00 hours) using MEGA‐PRESS. The blood pressure, HR and sputum MT levels, were also acquired.Statistical TestsThe one‐way repeated‐measures analysis of variance (ANOVA) was used to evaluate the GABA, blood pressure, HR, and MT levels throughout the day. A general linear model was used to find the correlation between GABA and blood pressure, HR, and MT. P < 0.05 was statistically significant.ResultsSignificant variations in GABA+/Cr and GABA+ levels were observed throughout the day within the PL region. The lowest levels were recorded at 9:00 hour (GABA+/Cr: 0.100 ± 0.003，GABA+:1.877 ± 0.051 i.u) and the highest levels were recorded at 21:00 hour (GABA+/Cr: 0.115 ± 0.003, GABA+:2.122 ± 0.052 i.u). The MT levels were positively correlated with GABA+/Cr (r = 0.301) and GABA+ (r = 0.312) within the ACC region.Data ConclusionGABA+/Cr and GABA+ in ACC are positively correlated with MT. GABA levels in the PL have diurnal differences. These findings may indicate that the body's GABA level change in response to the light–dark cycle.Level of Evidence1Technical EfficacyStage 2