GLUT4 translocation is not impaired after acute exercise in skeletal muscle of women with obesity and polycystic ovary syndrome.

OBJECTIVE: The aim of this study was to examine the effects of acute exercise on insulin signaling in skeletal muscle of women with polycystic ovary syndrome (PCOS) and controls (CTRL). METHODS: Fifteen women with obesity and PCOS and 12 body mass index-matched CTRL participated in this study. Subjects performed a 40-min single bout of exercise. Muscle biopsies were performed before and 60 min after exercise. Selected proteins were assessed by Western blotting. RESULTS: CTRL, but not PCOS, showed a significant increase in PI3-k p85 and AS160 Thr 642 after a single bout of exercise (P = 0.018 and P = 0.018, respectively). Only PCOS showed an increase in Akt Thr 308 and AMPK phosphorylation after exercise (P = 0.018 and P = 0.018, respectively). Total GLUT4 expression was comparable between groups (P > 0.05). GLUT4 translocation tended to be significantly higher in both groups after exercise (PCOS: P = 0.093; CTRL: P = 0.091), with no significant difference between them (P > 0.05). CONCLUSIONS: A single bout of exercise elicited similar GLUT4 translocation in skeletal muscle of PCOS and CTRL, despite a slightly differential pattern of protein phosphorylation. The absence of impairment in GLUT4 translocation suggests that PCOS patients with obesity and insulin resistance may benefit from exercise training.

Can creatine supplementation form carcinogenic heterocyclic amines in humans?

There is a long-standing concern that creatine supplementation could be associated with cancer, possibly by facilitating the formation of carcinogenic heterocyclic amines (HCAs). This study provides compelling evidence that both low and high doses of creatine supplementation, given either acutely or chronically, does not cause a significant increase in HCA formation. HCAs detection was unrelated to creatine supplementation. Diet was likely to be the main factor responsible for HCAs formation after either placebo (n = 6) or creatine supplementation (n = 3). These results directly challenge the recently suggested biological plausibility for the association between creatine use and risk of testicular germ cell cancer. Creatine supplementation has been associated with increased cancer risk. In fact, there is evidence indicating that creatine and/or creatinine are important precursors of carcinogenic heterocyclic amines (HCAs). The present study aimed to investigate the acute and chronic effects of low- and high-dose creatine supplementation on the production of HCAs in healthy humans (i.e. 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx), 2-amino-(1,6-dimethylfuro[3,2-e]imidazo[4,5-b])pyridine (IFP) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx)). This was a non-counterbalanced single-blind crossover study divided into two phases, in which low- and high-dose creatine protocols were tested. After acute (1 day) and chronic supplementation (30 days), the HCAs PhIP, 8-MeIQx, IFP and 4,8-DiMeIQx were assessed through a newly developed HPLC-MS/MS method. Dietary HCA intake and blood and urinary creatinine were also evaluated. Out of 576 assessments performed (from 149 urine samples), only nine (3 from creatine and 6 from placebo) showed quantifiable levels of HCAs (8-MeIQx: n = 3; 4,8-DiMeIQx: n = 2; PhIP: n = 4). Individual analyses revealed that diet rather than creatine supplementation was the main responsible factor for HCA formation in these cases. This study provides compelling evidence that both low and high doses of creatine supplementation, given either acutely or chronically, did not cause increases in the carcinogenic HCAs PhIP, 8-MeIQx, IFP and 4,8-DiMeIQx in healthy subjects. These findings challenge the long-existing notion that creatine supplementation could potentially increase the risk of cancer by stimulating the formation of these mutagens.

Effects of 17beta-estradiol replacement on the apoptotic effects caused by ovariectomy in the rat hippocampus.

AIMS: The aim of the present study was to investigate the effects of different periods of ovariectomy and 17beta-estradiol replacement on apoptotic cell death and expression of members of the Bcl-2 family in the rat hippocampus. MAIN METHODS: Hippocampi were obtained from rats in proestrus, ovariectomized (15 days, 21 days and 36 days), ovariectomized for 15 days and then treated with 17beta-estradiol for 7 or 21 days, and rats ovariectomized and immediately treated with 17beta-estradiol for 21 days. The expression of Bcl-2 and Bax and the number of apoptotic cells were determined. KEY FINDINGS: Ovariectomy decreased Bcl-2 expression and increased Bax expression and the number of apoptotic cells. Replacement with 17beta-estradiol (21 days) throughout the post-ovariectomy period reduced the number of apoptotic cells to the control levels, and prevented the effects of ovariectomy on Bax expression, but only partially restored the Bcl-2 expression. After 15 days of ovariectomy, the replacement with 17beta-estradiol for 21 days, but not for 7 days, restored the Bcl-2 and Bax expression and the percentage of apoptotic cells to the levels found in the proestrus control. SIGNIFICANCE: The present results show that a physiological concentration of 17beta-estradiol may help maintain long-term neuronal viability by regulating the expression of members of the Bcl-2 family. Even after a period of hormonal deprivation, treatment with 17beta-estradiol is able to restore the expression of Bax and Bcl-2 to control levels, but the duration of the treatment is a key factor to obtain the desired effect. These data provide new understanding into the mechanisms contributing to the neuroprotective action of estrogen.

Effects of 17â-estradiol replacement on the apoptotic effects caused by ovariectomy in the rat hippocampus

The aim of the present study was to investigate the effects of different periods of ovariectomy and 17â- estradiol replacement on apoptotic cell death and expression of members of the Bcl-2 family in the rat hippocampus. Hippocampi were obtained from rats in proestrus, ovariectomized (15 days, 21 days and 36 days), ovariectomized for 15 days and then treated with 17â-estradiol for 7 or 21 days, and rats ovariectomized and immediately treated with 17â-estradiol for 21 days. The expression of Bcl-2 and Bax and the number of apoptotic cells were determined. Ovariectomy decreased Bcl-2 expression and increased Bax expression and the number of apoptotic cells. Replacement with 17â-estradiol (21 days) throughout the post-ovariectomy period reduced the number of apoptotic cells to the control levels, and prevented the effects of ovariectomy on Baxexpression, but only partially restored the Bcl-2 expression. After 15 days of ovariectomy, the replacementwith 17â-estradiol for 21 days, but not for 7 days, restored the Bcl-2 and Bax expression and the percentageof apoptotic cells to the levels found in the proestrus control.The present results show that a physiological concentration of 17â-estradiol my help maintainlong-term neuronal viability by regulating the expression of members of the Bcl-2 family. Even after a period of hormonal deprivation, treatment with 17â-estradiol is able to restore the expression of Bax and Bcl-2 to control levels, but the duration of the treatment is a key factor to obtain the desired effect. These dataprovide new understanding into the mechanisms contributing to the neuroprotective action of estrogen.

Effects of estrogen on intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors and on acetylcholinesterase activity in rat hippocampus.

The aim of the present study was to investigate the effects of estrogen lack and estrogen replacement on the production of total [3H]inositol phosphate ([3H]IP) induced by the activation of muscarinic acetylcholine receptors (mAChRs) and on the mechanisms for inactivation of acetylcholine. Hippocampi were obtained from rats in proestrus (PE), ovariectomized for 15 days (C15), ovariectomized for 15 days and then treated with 17beta-estradiol for 7 days (E7) and ovariectomized and immediately treated with 17beta-estradiol for 21 days (E21). Ovariectomy did not change the basal level of total [3H]IP in the hippocampus. 17beta-Estradiol replacement (E7 and E21) reduced the basal level of total [3H]IP. In all experimental groups, carbachol (CCh) caused a concentration-dependent rise in total [3H]IP. The maximum effect was reached with 10(-4) M CCh. The response to 10(-4) M CCh in the hippocampi from C15 and E7 rats was twofold higher than in hippocampi from PE and E21 animals and was blocked by pirenzepine, but not by methoctramine. Ovariectomy or 17beta-estradiol treatment for 7 days did not change neither the total acetylcholinesterase (AChE) activity nor the relative amount of mono- and dimeric G1/G2 and tetrameric G4 globular forms. Conversely, hormonal treatment for 21 days induced an increase in AChE activity of G1/G2 and G4 forms, indicating that 17beta-estradiol stimulates both synthesis and assembly of AChE molecular forms. The present results suggest that the duration and/or a critical period with regard to the initiation of estrogen therapy are important to regulate the function of mAChRs and AChE activity in female rat hippocampus.

Effects of estrogen on intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors and on acetylcholinesterase activity in rat hippocampus

The aim of the present study was to investigate the effects of estrogen lack and estrogen replacement on the production of total [3H]inositol phosphate ([3H]IP) induced by the activation of muscarinic acetylcholine receptors (mAChRs) and on the mechanisms for inactivation of acetylcholine. Hippocampi were obtained from rats in proestrus (PE), ovariectomized for 15 days (C15), ovariectomized for 15 days and then treated with 17â-estradiol for 7 days (E7) and ovariectomized and immediately treated with 17â-estradiol for 21 days (E21). Ovariectomy did not change the basal level of total [3H]IP in the hippocampus. 17â-Estradiol replacement (E7 and E21) reduced the basal level of total [3H]IP. In all experimental groups, carbachol (CCh) caused a concentration-dependent rise in total [3H]IP. The maximum effect was reached with 10-4 M CCh. The response to 10-4 M CCh in the hippocampi from C15 and E7 rats was twofold higher than in hippocampi from PE and E21 animals and was blocked by pirenzepine, but not by methoctramine. Ovariectomy or 17â-estradiol treatment for 7 days did not change neither the total acetylcholinesterase (AChE) activity nor the relative amount of mono- and dimeric G1/G2 and tetrameric G4 globular forms. Conversely, hormonal treatment for 21 days induced an increase in AChE activity of G1/G2 and G4 forms, indicating that 17â-estradiol stimulates both synthesis and assembly of AChE molecular forms. The present results suggest that the duration and/or a critical period with regard to the initiation of estrogen therapy are important to regulate the function of mAChRs and AChE activity in female rat hippocampus.