The impact of matching for reproductive status on the comparison of magnetic spectroscopic measurements of glutamate and gamma-aminobutyric acid + in the medial prefrontal cortex of women with major depression.

OBJECTIVES: The role played by medial prefrontal cortex (MPFC) glutamate (Glu) and gamma-aminobutyric acid (GABA) in the pathophysiology and the treatment of major depression (MD) is increasingly recognized. Although measurements of MPFC GABA and Glu have been shown to be sensitive to physiological fluctuations of female hormones, none of the magnetic resonance spectroscopy (MRS) investigations of MPFC Glu and GABA in MD have controlled for possible bias effect of the reproductive stage of the women included. METHODS: MPFC Glu and GABA+ (which include homocarnosine and macromolecules) referenced to creatine and phosphocreatine, were measured via magnetic resonance spectroscopy (MRS) using a 3-Tesla magnet in 24 women with MD and 24 healthy women paired for reproductive status. All participants were unmedicated. RESULTS: There were no statistical differences in either MPFC Glu [95 % CI: (-0.025, 0.034)] or MPFC GABA+ [95 % CI: (-0.005, 0.017)] between women with MD and healthy controls. CONCLUSIONS: Our investigation does not support abnormalities in measurement of MPFC Glu and GABA in MD women when stringent control for reproductive status is performed. As a result of the inherent limitations of MRS methodology, our results do not preclude glutamatergic and GABAergic dysregulations in the MPFC of women with MD.

Decreased GABA+ ratios referenced to creatine and phosphocreatine in the left dorsolateral prefrontal cortex of females of reproductive age with major depression.

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 γ-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.

Development of a High-Throughput Urosepsis Mouse Model.

Murine sepsis models are typically polymicrobial, and are associated with high mortality. We aimed to develop a high-throughput murine model that mimics a slow-paced, monomicrobial sepsis originating from the urinary tract. A total of 23 male C57Bl/6 mice underwent percutaneous insertion of a 4 mm catheter into the bladder using an ultrasound-guided method, previously developed by our group. The following day, Proteus mirabilis (PM) was introduced percutaneously in the bladder in three groups: g1-50 µL 1 × 108 CFU/mL solution (n = 10); g2-50 µL 1 × 107 CFU/mL solution (n = 10); and g3 (sham mice)-50 µL sterile saline (n = 3). On day 4, mice were sacrificed. The number of planktonic bacteria in urine, adherent to catheters, and adherent to/invaded into the bladder and spleen was assessed. Cell-free DNA, D-dimer, thrombin-antithrombin complex (TAT), and 32 pro-/anti-inflammatory cytokines/chemokines were quantified in the blood. All mice survived the 4 day postinterventional period. Mean weight loss was 11% in g1, 9% in g2, and 3% in the control mice. Mean urine CFU counts were highest in group 1. All catheters showed high catheter-adhered bacterial counts. Of the infected mice, 17/20 had CFU counts in the splenic tissue, indicating septicemia. Plasma levels of cell-free DNA, D-dimer, and the proinflammatory cytokines IFN-γ, IL-6, IP-10, MIG, and G-CSF were significantly elevated in infected mice versus controls. We present a reproducible, monomicrobial murine model of urosepsis that does not lead to rapid deterioration and death, and is useful for studying prolonged urosepsis.

Decreased GABA+ Levels in the Medial Prefrontal Cortex of Perimenopausal Women: A 3T 1H-MRS Study.

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.

A comparative magnetic resonance spectroscopy study of GABA+ and glutamate referenced to creatine and phosphocreatine in the left dorsolateral prefrontal cortex of perimenopausal women and women of reproductive age.

Objective: The perimenopause is associated with an increased risk of developing a major depressive (MD) episode. The biological changes occurring during perimenopause responsible for this increased risk of depression remain to be elucidated. Postmortem and magnetic resonance spectroscopy (MRS) studies have revealed decreased gamma-aminobutyric acid (GABA) and glutamate (Glu) levels in the dorsolateral prefrontal cortex (DLPFC) of MD patients. The objective of this study was to compare LDLPFC GABA+ and Glu ratios (referenced to creatine and phosphocreatine) in healthy reproductive-aged (RD) and perimenopausal (PM) women. Materials and methods: Eighteen healthy PM and 20 RD women were included in the study. Our dependent variables, LDLPFC Glu and GABA+ ratios which include homocarnosine and macromolecules, were measured via MRS, using a 3 Tesla magnet. 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 (MC). PM women were scanned outside of ovulatory cycles. Results: Mean LDLPFC GABA+ and Glu ratios were not statistically different between the PM group and RD group (PM mean = 0.10 ± 0.06, RD mean = 0.11 ± 0.04, t = -0.383, df = 36, d = -0.13, p = 0.70) (PM mean = 0.56 ± 0.06, RD mean = 0.57 ± 0.05, t = -0.794, df = 36, d = -0.26, p = 0.43), respectively. The perimenopause demarcates the end of the reproductive life. Unsurprisingly PM women were older than RD women (PM women: 48.8 ± 3.55 years, range 41-53 years old; RD women: 31.5 ± 9.66 years, range 18-47 years old) (p < 0.001). This inherent entanglement of group and age is a limitation of our study. Conclusion: Contrary to our previous findings of decreased GABA+ and Glu in the medial prefrontal cortex in perimenopausal women, the perimenopause is not associated with decreased GABA+ or Glu ratios in the LDLPFC. This suggests that brain areas playing a role in MD display different sensitivity to the female hormones fluctuations associated with perimenopause.

Decreased Medial Prefrontal Cortex Glutamate Levels in Perimenopausal Women.

Objective: There is an increased risk of experiencing depression during perimenopause (PM), a period of rapidly changing female hormone concentrations. Women at particular risk of developing major depression (MD) during PM are those with history of mood sensitivity to female hormone fluctuations i.e., women with a history of premenstrual dysphoric disorder (PMDD) and/or post-partum depression (PPD). Depressive symptomology has been associated with fluctuations of glutamate (Glu) levels in the medial prefrontal cortex (MPFC) in MD patients as well as PMDD and PPD patients. The objective of the study was to compare MPFC Glu levels in healthy perimenopausal and reproductive-aged (RD) women. Methods: Medial prefrontal cortex Glu levels in healthy perimenopausal (n = 15) and healthy RD women (n = 16) were compared via Magnetic Resonance Spectroscopy (MRS) scan using a 3 Tesla (T) magnet. Absence of depressive symptomology and psychiatric comorbidity was confirmed via semi-structured interview. Participants were scanned during the early follicular phase (FP) of the menstrual cycle (MC). Results: Mean MPFC Glu concentrations were decreased in the PM group compared to RD group (PM mean = 0.57 ± 0.03, RD mean = 0.63 ± 0.06, t = -3.84, df = 23.97, p = 0.001). Conclusion: Perimenopause is associated with decreases in MPFC Glu levels. This decrease may be contributing to the increased risk of experiencing depression during PM. Further research should assess MPFC Glu levels in perimenopausal women suffering from MD.