Relationship between body mass index and hippocampal glutamate/glutamine in bipolar disorder.

BACKGROUND: We previously reported that patients with early-stage bipolar disorder, but not healthy comparison controls, had body mass index (BMI)-related volume reductions in limbic brain areas, suggesting that the structural brain changes characteristic of bipolar disorder were more pronounced with increased weight. AIMS: To determine whether the most consistently reported neurochemical abnormality in bipolar disorder, increased glutamate/glutamine (Glx), was also more prominent with higher BMI. METHOD: We used single-voxel proton magnetic resonance spectroscopy to measure hippocampal Glx in 51 patients with first-episode mania (mean BMI = 24.1) and 28 healthy controls (mean BMI = 23.3). RESULTS: In patients, but not healthy controls, linear regression demonstrated that higher BMI predicted greater Glx. Factorial ANCOVA showed a significant BMI × diagnosis interaction, confirming a distinct effect of weight on Glx in patients. CONCLUSIONS: Together with our volumetric studies, these results suggest that higher BMI is associated with more pronounced structural and neurochemical limbic brain changes in bipolar disorder, even in early-stage patients with low obesity rates.

Effects of a single bout of maximal aerobic exercise on BDNF in bipolar disorder: A gender-based response.

Acute exercise increases brain-derived neurotrophic factor (BDNF) serum levels in majorly depressed and anxious patients. However, to the best of our knowledge, no study has evaluated the acute effects of exercise on BDNF serum levels in Bipolar Disorder (BD). The objective of the present study was to evaluate the peripheral BDNF serum response to a single maximum session of exercise in BD participants and age- and gender-matched healthy participants. BD participants (n=18) and age- and gender-matched healthy participants (n=18) were recruited to perform a single bout of maximal exercise on a cycle ergometer. Blood samples were collected prior to and immediately after the exercise protocol. There was a significant group effect and a significant group x time x gender interaction. BD participants presented significantly higher BDNF serum levels when compared to their healthy control counterparts. Exercise increases the BDNF levels of BD women, but not men.

Amnesic effect of GMP depends on its conversion to guanosine.

Extracellular guanine-based purines, namely the nucleotides GTP, GDP, GMP and the nucleoside guanosine, exert important neuroprotective and neuromodulator roles in the central nervous system, which may be related to inhibition of the glutamatergic neurotransmission activity. In this study, we investigated GMP effects on mice inhibitory avoidance performance and the dependence on its conversion to guanosine for such effect, by using the ecto-5'-nucleotidase specific inhibitor AOPCP. We also investigated if this conversion occurs in the central nervous system or peripherally, and if guanosine and GMP affect nociception by the tail-flick test. I.p. GMP or guanosine (7.5 mg/kg) or i.c.v. GMP (480 nmol) pretraining administration was amnesic for the inhibitory avoidance task. I.c.v. AOPCP (1 nmol) administration completely reversed the amnesic effect of i.c.v. GMP, but not of i.p. GMP, indicating that peripheral conversion of GMP to guanosine is probably relevant to this effect. AOPCP alone did not interfere with the performance. Furthermore, tail-flick measurement was unaffected by i.p. GMP and guanosine, suggesting that the amnesic effect of both purines was not due to some antinociceptive effect against the footshock used in the task. All these data together, in accordance to those previously observed in studies involving glutamate uptake and seizures reinforce the idea that guanosine is the specific extracellular guanine-based purines effector and indicate that its conversion occurs not only in the central nervous system but also peripherally.