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Background: It has been suggested that the dorsolateral prefrontal cortex (DLPFC), especially the left DLPFC, has an important role in the pathophysiology and the treatment of major depressive disorder (MDD); furthermore, the contributory and antidepressant role of y-aminobutyric acid (GABA) is increasingly recognized. Given that most female patients with MDD are of reproductive age, we sought to assess in vivo baseline GABA levels in the left DLPFC among unmedicated females of reproductive age with depression. Methods: We compared healthy females and females with MDD. Both groups were of reproductive age. We confirmed absence of current or past psychiatric diagnosis among healthy controls or a current diagnosis of MDD via a structured interview. We measured GABA+ (including homocarnosine and macromolecules), referenced to creatine and phosphocreatine, via magnetic resonance spectroscopy using a 3 Tesla magnet. Results: We included 20 healthy controls and 13 participants with MDD. All participants were unmedicated at the time of the study. All females were scanned during the early follicular phase of the menstrual cycle. Levels of GABA+ in the left DLPFC were significantly lower among participants with MDD (median 0.08) than healthy controls (median 0.10; U = 66.0, p = 0.02, r = 0.41). Limitations: When we adjusted for fit error as a covariate, we lost statistical significance for left DLPFC GABA+. However, when we adjusted for signal-to-noise ratio, statistical significance was maintained. Conclusion: Our results suggest that GABA+ levels in the left DLPFC may vary by depression status and should be examined as a possible treatment target., Introduction It has been suggested that the dorsolateral prefrontal cortex (DLPFC), especially the left DLPFC, has a role in the pathophysiology and the treatment of major depressive disorder (MDD). Positron [...]

Objective Perimenopause is associated with an increased risk of developing a major depressive (MD) episode. A significant number of women develop their first MD episode during perimenopause, suggesting a unique pathophysiology of perimenopausal (PM) depression. Previous research has shown that depression is associated with decreased gamma-aminobutyric acid (GABA) levels in the medial prefrontal cortex (MPFC) of MD patients. The objective of this study was to compare MPFC GABA+ levels in healthy reproductive-aged (RD) and PM women. Methods A total of 18 healthy PM and 20 RD women were included in the study. MPFC GABA+ levels, which include homocarnosine and macromolecules, were measured via magnetic resonance spectroscopy using a 3 Tesla magnet. MPFC GABA+ levels were referenced to creatine + phosphocreatine (Cr+PCr). Absence of current or past psychiatric diagnosis was confirmed via a structured interview. RD participants were scanned during the early follicular phase of the menstrual cycle. PM women were scanned outside of ovulatory cycles. Results Mean MPFC GABA+ concentrations (relative to Cr+PCr) were decreased in the PM group compared with the RD group (PM mean = 0.08 ± 0.02, RD mean = 0.09 ± 0.02, t  = −2.03, df  = 36, P  = .05) even after correcting for in percentage in gray matter (GM). Because PM women were inherently older than RD women (aged 48.8 ± 3.55 and 31.5 ± 9.66 years, respectively), the age difference between the 2 groups was statistically significant (P  < .001). When age was treated as an independent covariate and included in the model, the difference in GABA+ between PM and RD women was no longer significant (P  = .092). Conclusion Perimenopause is associated with decreased MPFC GABA+/Cr+PCr levels, which may contribute to the increased risk of experiencing a MD episode during PM. [ABSTRACT FROM AUTHOR]

Trump, Mark E., Christopher C. Hanstock, Peter S. Allen, Daniel Gheorghiu, and Peter W. Hoehachka. An [sup.1] H-MRS evaluation of the phosphocreatine/creatine pool (tCr) in human muscle. Am J Physiol Regulatory Integrative Comp Physiol 280: R889-R896, 2001.--The human gastrocnemius was examined with and without creatine supplementation under the conditions of rest, ischemic fatigue (IF), and recovery to perturb the pool sizes and equilibrium between phosphocreatine (PCr) and creatine (Cr). [sup.1]H- and [sup.31]P-magnetic resonance spectroscopy (MRS) were used to examine the total creatine (tCr) pool in each of the metabolic states. [sup.31]P-MRS monitored the depletion of the PCr peak during IF to [is less than] 5% of that at rest. [sup.1]H-MRS focused on the tCr methyl peak at 3.02 ppm (dipolar coupled triplet), at which point it was expected that the triplet peak intensity would be similar both in IF and rest. Initial [sup.1]H-MRS data showed the peak intensity during IF decreased, suggesting a change in tCr pool size. Subsequent studies of transverse relaxation time ([T.sub.2]) revealed that this decline was primarily due to a more rapid [T.sub.2] decay of the tCr peak in IF ([T.sub.2] ~40 ms) compared with at rest ([T.sub.2] ~162 ms). Because Cr is the major contributor to tCr in IF, it is possible that there is a pool of Cr displaying reduced mobility in vivo. Moreover, the residual dipolar coupled triplet observed at rest collapsed into a broad singlet during IF, suggestive of significant changes in the ordered environment experienced at rest for PCr compared with when it is converted to Cr during IF. In addition, these data suggest that in [sup.1]H-MRS studies whose goals include quantitative estimates of tCr pool sizes, standardized metabolic conditions or careful [T.sub.2] evaluations will be required. [sup.1]H-magnetic resonance spectroscopy; [sup.31]P-magnetic resonance spectroscopy; muscle phosphagen; creatine compartmentalization; metabolite mobility

An optimized single-shot proton double-quantum (DQ) filter for the quantification of γ-aminobutyric acid (GABA) levels in human brain is reported. It is demonstrated that creation of DQ coherences following dual-resonance-selective refocusing gives a theoretical editing efficiency of 50% for the detection of the GABA resonance at 3.01 ppm. The sequence times are optimized with both numerical and experimental analyses of the editing performance, giving an experimental editing efficiency of 42%. It is acknowledged that homocarnosine is partially coedited, leading to a 20% contribution to the edited signal; however, macromolecule contamination is negligible in vivo under these experimental conditions. The GABA concentration in human prefrontal cortex is estimated to be 0.8 ± 0.1 μmol/g (mean ± SD, n = 6), with reference to the internal standard creatine at 9 μmol/g. Magn Reson Med 54:272-279, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Discusses the results of an [sup 1]H-magnetic resonance spectroscopy evaluation of the phosphocreatine/creatine pool (tCr) in the human muscle. Possibility that there is a pool of creatine displaying reduced mobility in vivo; Recommendation of standardized metabolic conditions or careful transverse relaxation time evaluations in future research.

Focuses on proton magnetic resonance spectroscopy of the cerebellum in men with schizophrenia. Cerebellar vermis abnormalities; Use of spectral peak arising from N-acetylaspartate, phosphocreatine/creatine and choline; Schizophrenia through mechanisms such as aberrant circuitry.