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Endocrinological and catecholaminergic alterations during sleep deprivation and recovery in male rats

Since previous data of our group showed increased concentrations in HPA axis hormones in sleep deprived rats, we hypothesized that this augmentation could produce effects in other hormonal systems, particularly in the sexual system. Considering that little is known about how the hormonal system changes during the recovery period after sleep deprivation (SD), our objective was to examine from what point SD alters sexual and stress‐related hormones along with plasma catecholamine concentrations during 4 days. We also sought to verify the time course of their recovery after an equivalent period of recovery sleep. Rats were deprived of sleep by the platform technique for 1–4 days and were allowed to recover for the same period. Plasma catecholamines [dopamine (DA) and noradrenaline (NOR)], testosterone, estrone, progesterone, prolactin, corticosterone and adrenocorticotropic hormone (ACTH) concentrations were measured. Comparisons between groups showed that the SD procedure used in the present study produced marked alterations in almost all studied hormones from 24 h of SD, except for estrone and prolactin (which required 96 h of SD to become altered). Testosterone and estrone decreased, whereas progesterone, prolactin, corticosterone, ACTH, DA and NOR increased. During recovery period, progesterone, prolactin and corticosterone concentrations returned to control levels, whereas testosterone, estrone, NOR and DA did not. In addition, after 48 h of recovery ACTH and NOR decreased below control concentrations, remaining low until 96 h of sleep recovery. Thus, SD showed long lasting, differential effects upon these neurochemicals suggesting that each has its own pattern of responses to SD as well as variable periods of recovery.

Relationship between total homocysteine and folate levels in pregnant women and their newborn babies according to maternal serum levels of vitamin B12

Objective To determine total homocysteine and folate levels in pregnant women according to vitamin B12 (B12) levels, and to analyse the impact of maternal B12 levels on the nutritional status of their newborn babies.

Increased hypocretin-1 (orexin-a) levels in cerebrospinal fluid of rats after short-term forced activity

The hypocretins (orexins) are recently discovered neuropeptides initially associated with feeding behavior and sleep regulation. However, the normal function of these peptides is unclear and a number of studies have reported a role in energy homeostasis and locomotor activity. Exercise (or physical activity) is the most powerful way of challenging the internal homeostatic process. This study examines the circadian differences in response to forced activity and homeostatic challenges on hypocretin-1 (Hcrt-1) levels in the cerebrospinal fluid (CSF) of rats. Hcrt-1 levels were decreased after long-term immobilization at the end of active phase (zeigeber time-0, ZT-0) and increased after short-term forced swimming in the rest phase (ZT-8). Nevertheless, no effects were observed after short-term immobilization, total sleep deprivation or cold exposure. We concluded that despite the relation between hypocretins, stress and sleep regulation reported in the literature, short-term total sleep deprivation, immobilization and cold exposure did not induce increases in CSF Hcrt-1 levels at ZT-0 and ZT-8. On the other hand, the relationship between hypocretinergic system activation and motor activation is reinforced by decrease in Hcr-1 levels after long-term immobilization at ZT-0 and its increased levels after short-term forced swimming at ZT-8 in CSF of rats.

Relationship Between Polymorphisms in Genes Involved in Homocysteine Metabolism and Maternal Risk for Down Syndrome in Brazil

Associations between specific alleles of genes encoding enzymes in the methionine/homocysteine pathway and plasma homocysteine levels have been examined in different populations. In the present study, we determined polymorphisms of MTHFR A222V (677C > T), MTHFR E429A (1298A > C), MTRR I22M (66A > G), MTR D919G (2756A > G), and CBS 844ins68 and total plasma homocysteine levels (tHcy) among 154 mothers of children with Down syndrome (DS) and 158 control mothers from Brazil. Homocysteine levels were higher among DS mothers compared to control groups (10.437 vs. 8.600 respectively, P = 0.002). Only the 677T allele was associated with altered levels of tHcy in the case group (F(2,153) = 5.300; P = 0.006), primarily when homozygous. In the control group, the association of the TT genotype with higher levels of tHcy showed borderline significance (F(2,157) = 2.974; P = 0.054). All genotype distributions were similar in the two groups (P > 0.05), but the frequency of the 677T allele in the case group was significantly higher (χ2 = 3.862; DF = 1; P = 0.049; OR = 1.437 (1.001–2.062)). Although the 677T allele is associated with increased homocysteine levels, its presence has only a modest impact as an independent risk factor for DS. All the other polymorphisms did not show an association with risk for the syndrome, when evaluated separately (P > 0.05). However, when the presence of 677T, 1298C, 2756G, 66G, and 844ins68 alleles were evaluated together, the mothers of children with DS tend to have a higher number of uncommon alleles than the mothers with no previous affected child.

OREXIN ACTIVATION PRECEDES INCREASED NPY EXPRESSION, HYPERPHAGIA AND METABOLIC CHANGES IN RESPONSE TO SLEEP DEPRIVATION

Several pieces of evidence support that sleep duration plays a role in body weight control. Nevertheless, it has been assumed that, after the identification of orexins (hypocretins), the molecular basis of the interaction between sleep and energy homeostasis has been provided. However, no study has verified the relationship between neuropeptide Y (NPY) and orexin changes during hyperphagia induced by sleep deprivation. In the current study we aimed to establish the time course of changes in metabolite, endocrine, and hypothalamic neuropeptide expression of Wistar rats sleep deprived by the platform method for a distinct period (from 24 to 96 h) or sleep restricted for 21 days (SR-21d). Despite changes in the stress hormones, we found no changes in food intake and body weight in the SR-21d group. However, sleep-deprived rats had a 25-35% increase in their food intake from 72 h accompanied by slight weight loss. Such changes were associated with increased hypothalamus mRNA levels of prepro-orexin (PPO) at 24 h followed by NPY at 48 h of sleep deprivation. Conversely, sleep recovery reduced the expression of both PPO and NPY, which rapidly brought the animals to a hypophagic condition. Our data also support that sleep deprivation rapidly increases energy expenditure and therefore leads to a negative energy balance and a reduction in liver glycogen and serum triacylglycerol levels despite the hyperphagia. Interestingly, such changes were associated with increased serum levels of glucagon, corticosterone, and norepinephrine, but no effects on leptin, insulin, or ghrelin were observed. In conclusion, orexin activation accounts for the myriad changes induced by sleep deprivation, especially the hyperphagia induced under stress and a negative energy balance.

Vitamin E attenuates reserpine-induced oral dyskinesia and striatal oxidized glutathione/reduced glutathione ratio (GSSG/GSH) enhancement in rats

The effects of a previous and concomitant treatment with vitamin E (VE) were studied on an animal model of tardive dyskinesia, i.e., the frequency of spontaneous tongue protrusions in rats treated with reserpine (RE). VE (5, 10, 20 or 40 mg/kg administered intraperitoneally, daily, for 19 days) attenuated the increase in tongue protrusion frequency induced by RE (1 mg/kg administered subcutaneously, on Days 16 and 18, 1 h after VE), which was quantified on Day 19. In a second experiment, a similar treatment with 20 mg/kg VE attenuated RE-induced increase in the striatal ratio of oxidized/reduced glutathione (GSSG/GSH), an index of the oxidative stress process. These results support the free radical hypothesis of tardive dyskinesia.

Effects of paradoxical sleep deprivation on blood parameters associated with cardiovascular risk in aged rats

The effects of 96 h of paradoxical sleep deprivation (PSD) on blood parameters associated with cardiovascular risk were studied in young (3-month old) and aged (22-month old) rats. In general, aging was associated with an overall increase in most measures, irrespective of sleep deprivation condition. The latter manipulation also had significant effects on blood variables, but not in a consistent pattern. Thus, PSD significantly reduced triglyceride levels in both young and aged rats; it reduced blood viscosity in aged but not in young rats, and had no effect on the increased cholesterol levels observed in aged controls. Examinations of cholesterol fractions revealed significant increases in low density lipoprotein and high density lipoprotein in aged PSD rats compared to respective controls, whereas very low density lipoprotein was significant decreased after PSD in both young and aged animals. PSD increased vitamin B(12) levels in aged rats, and significantly decreased homocysteine levels in young but not in aged rats which in turn were already reduced. Folate levels were the only variable that was unaffected by aging and/or PSD. These results indicate that PSD has significant but heterogeneous physiological effects in aged rats and may intensify certain aging-related effects which contribute to cardiovascular disease risk while attenuating others.

Methylenetetrahydrofolate reductase (MTHFR): incidence of mutations C677T and A1298C in Brazilian population and its correlation with plasma homocysteine levels in spina bifida

Homocysteine (Hcy) is converted to cysteine or is remethylated to methionine by methylenetetrahydrofolate reductase (MTHFR). MTHFR plays a central role in the metabolism of folate. Two common polymorphisms in the MTHFR gene (C677T and A1298C) have been described and studies suggest that these polymorphisms are positively associated with the occurrence of spina bifida (SB). Among Brazilians, the incidence of 677T allele homozygosity is 4%. We compared Hcy levels with the genotypes obtained for the mutations C677T and A1298C in the gene MTHFR. Levels of plasma Hcy were higher in children with SB than in controls (average 7.95 vs. 5.55 (μmol/L); P < 0.001). There was no significant difference in the levels of Hcy for these childrenss mothers and controls (average 7.76 vs. 8.36 (μmol/L); P = 0.27). Eighty one (61.8%) of the affected children were white and 50 (38.2%) were non‐white. A similar ratio was observed in the mothers. In the control group, 51 children (40.5%) were white and 75 (59.5%) were non‐white, and 52 mothers (41.3%) were white and 74 (58.7%) were non‐white. There was no significant difference in the homozygous frequency for the mutated allele 677T among different racial groups. We obtained a prevalence of TT homozygosity of 10/131 (7.64%) in affected children and 13/126 (10.32%) in controls. With respect to the mutation A1298C, the homozygous prevalence for the wild allele was greater among non‐white individuals than in white individuals both in case and control groups. Hyperhomocysteinemia is a risk factor for SB. However, in our population, the increase in plasma levels of Hcy is not explained by the presence of the homozygous TT. It is possible that low folic acid intake combined with other genetic factors plays a more important role in the cause of this disease.

Endurance exercise training increases APPL1 expression and improves insulin signaling in the hepatic tissue of diet-induced obese mice, independently of weight loss

Hepatic insulin resistance is the major contributor to fasting hyperglycemia in type 2 diabetes. The protein kinase Akt plays a central role in the suppression of gluconeogenesis involving forkhead box O1 (Foxo1) and peroxisome proliferator‐activated receptor gamma co‐activator 1 alpha (PGC‐1α), and in the control of glycogen synthesis involving the glycogen synthase kinase beta (GSK3β) in the liver. It has been demonstrated that endosomal adaptor protein APPL1 interacts with Akt and blocks the association of Akt with its endogenous inhibitor, tribbles‐related protein 3 (TRB3), improving the action of insulin in the liver. Here, we demonstrated that chronic exercise increased the basal levels and insulin‐induced Akt serine phosphorylation in the liver of diet‐induced obese mice. Endurance training was able to increase APPL1 expression and the interaction between APPL1 and Akt. Conversely, training reduced both TRB3 expression and TRB3 and Akt association. The positive effects of exercise on insulin action are reinforced by our findings that showed that trained mice presented an increase in Foxo1 phosphorylation and Foxo1/PGC‐1α association, which was accompanied by a reduction in gluconeogenic gene expressions (PEPCK and G6Pase). Finally, exercised animals demonstrated increased at basal and insulin‐induced GSK3β phosphorylation levels and glycogen content at 24 h after the last session of exercise. Our findings demonstrate that exercise increases insulin action, at least in part, through the enhancement of APPL1 and the reduction of TRB3 expression in the liver of obese mice, independently of weight loss. J. Cell. Physiol. 227: 2917–2926, 2012.

The mitochondrial toxin 3-nitropropionic acid aggravates reserpine-induced oral dyskinesia in rats.

The effects of a previous long-term administration of the mitochondrial toxin 3-nitropropionic acid were studied on an animal model of tardive dyskinesia, i.e., the frequency of spontaneous tongue protrusions in rats repeatedly treated with reserpine. 3-Nitropropionic acid (10 or 15 mg/kg i.p., every other day for 17 days) potentiated the increase in tongue-protrusion frequency induced by reserpine (1 mg/kg, s.c., every other day for 3 days) but did not modify reserpine-induced increase in immobility duration and decrease in locomotion frequency. These results support the notion that neurotoxic events are associated with the development of tardive dyskinesia.