柚皮苷通过激活小鼠海马脑区mTOR信号通路发挥抗抑郁作用

目的:观察柚皮苷(NRG)对慢性不可预知应激(CUS)模型小鼠抑郁样行为及海马脑区mTOR信号通路的影响,探讨柚皮苷抗抑郁作用的机制.方法:将雄性C57BL/6小鼠随机分为4组:对照组(control)、柚皮苷处理组(NRG)、CUS处理组(CUS)、CUS和柚皮苷联合处理组(CUS+NRG).用糖水偏好实验和强迫游泳...     

Orange juice improved lipid profile and blood lactate of overweight middle-aged women subjected to aerobic training

Objective

This study investigated how consumption of orange juice associated with aerobic training affected serum lipids and physical characteristics of overweight, middle-aged women.

Methods

The experimental group consisted of 13 women who consumed 500 mL/d of orange juice and did 1 h aerobic training 3 times a week for 3 months. The control group consisted of another 13 women who did the same aerobic training program but did not consume orange juice.

Results

At the end of the experiment, the control group lost an average of 15% of fat mass (P < 0.05) and 2.5% of weight (P < 0.05), whereas the experimental group lost 11% of fat mass and 1.2% of weight (P < 0.05). Consumption of orange juice by the experimental group was associated with increased dietary intake of vitamin C and folate by 126% and 61% respectively. Serum LDL-C decreased 15% (P < 0.05) and HDL-C increased 18% (P < 0.05) in the experimental group, but no significant change was observed in the control group. Both groups improved the anaerobic threshold by 20% (P < 0.05), but blood lactate concentration decreased 27% in the experimental group compared to the 17% control group, suggesting that experimental group has less muscle fatigue and better response to training.

Conclusions

The consumption of 500 mL/d of orange juice associated with aerobic training in overweight women decreased cardiovascular disease risk by reducing LDL-C levels and increasing HDL-C levels. This association also decreased blood lactate concentration and increased anaerobic threshold, showing some improvement in the physical performance.     

Traumatic brain injury-induced expression and phosphorylation of pyruvate dehydrogenase: A mechanism of dysregulated glucose metabolism

Dysregulated brain glucose metabolism and lactate accumulation are seen following traumatic brain injury (TBI). The underlying molecular mechanism is poorly understood. Pyruvate dehydrogenase (PDH), the rate-limiting enzyme coupling cytosolic glycolysis to mitochondrial citric acid cycle, plays a critical role in maintaining homeostasis of brain glucose metabolism. PDH activity is maintained by the expression of its E1α1 subunit 1 (PDHE1α1) and is inhibited by the phosphorylation of PDHE1α1 (p-PDHE1α1). We hypothesized that PDHE1α1 expression and phosphorylation was altered in rat brain following controlled cortical impact (CCI)-induced TBI. Compared to naïve controls (=100%), PDHE1α1 protein decreased significantly ipsilateral to CCI (62%, P < 0.05; 75%, P < 0.05; 57%, P < 0.05; and 39%, P < 0.01) and contralateral to CCI (77%, 78%, 78% and 36% P < 0.01) at 4 h, 24 h, 3- and 7-day post-CCI, respectively. PDHE1α1 protein phosphorylation level also decreased significantly ipsilateral to CCI (31%, P < 0.01; 102%, P > 0.05; 64%, P < 0.05; and 14%, P < 0.01) and to contralateral CCI (35%, 74%, P < 0.05; 60%, P < 0.05; 20%, P < 0.01) at 4 h, 24 h, 3- and 7-day post-CCI, respectively. Similar reduction in PDHE1α1 and p-PDHE1α1 protein was found in the craniotomy (sham CCI) group. TBI-induced change in PDHE1α1 expression and phosphorylation could alter brain PDH activity and glucose metabolism.     

Adrenal reactivity in lines of domestic fowl selected on feather pecking behavior

Domestic chicken lines of the White Leghorn layer type differing in their level of feather pecking have been developed by divergent selection specifically on feather pecking behavior. This paper describes an investigation of basal level, reactivity to manual restraint and maximal adrenal response to 1-24 ACTH in breeder birds of the sixth generation of selection (S6) and their control line. Birds from the three lines had comparable basal levels of corticosterone (1.6 ng/ml, anova F_2,101 = 0.62, ns), whereas males had higher basal levels than females, lsmean 1.9 vs. 1.5 ng/ml (anova F_1,103 = 6.03, P < 0.05). Reactivity to handling and restraint for 10 min differed with HFP birds showing higher reactivity than LFP birds, lsmean 11.0 vs. 7.9 ng/ml (t = − 2.00, P < 0.05), while control birds showed intermediate levels (10.2 ng/ml). Males had higher reactivity than females, lsmean 11.2 vs. 8.2 ng/ml (anova F_1,103 = 3.96, P < 0.05). Maximal response did not differ between lines (average 35.7 ng/ml, anova F_2,101 = 1.38, P > 0.05). Males had higher maximal response than females, lsmean 41.3 vs. 33.6 ng/ml (anova F_1,103 = 5.77, P < 0.05). The present study shows that selection against feather pecking behavior have resulted in lower levels of feather pecking as well as lower sensitivity to human handling and restraint in White Leghorn laying hen lines. From an animal welfare point of view this is a positive relationship.     

Dehydroepiandrosterone in nails of infants: a potential biomarker of intrauterine responses to maternal stress

Easily accessible biomarkers for fetal stress biology are lacking. We here explore whether quantification of major fetal steroids, dehydroepiandrosterone (DHEA) or DHEA sulfate (DHEAS), with liquid chromatography/tandem mass spectrometry in infant nails is a tool to assess fetal stress biology in response to maternal stressful life events during pregnancy. Sufficient nail (≥1 mg) was available from 80 infants (93% of those providing samples). The concentration of DHEA, but not DHEAS, was increased in infants of mothers with stressful life events during pregnancy (DHEA: F_1,41 = 6.105, P = 0.018; DHEAS: F_1,77 = 0.767, P = 0.384). DHEA concentrations were not related to maternal stress before pregnancy (F_1,41 = 0.010, P = 0.922). Infant nail DHEA may be a fetal biological correlate of intrauterine exposure to maternal stress. The method promises the first non-invasive retrospective biomarker for intrauterine stress biology, opening new ways for research and clinical applications in fetal medicine, endocrinology, obstetrics, gynecology, and for understanding the developmental origins of health and disease.     

Polymorphisms of interleukin 6 and interleukin 10 in Egyptian people with Behcet's disease

Cytokines play critical roles in the pathogenesis of Behçet's disease (BD). They mediated many of the effectors and regulatory functions of immune and inflammatory responses. Many studies have linked Interleukin-6 (IL-6) and Interleukin-10 (IL-10) pathologically to BD. Thus, this study aimed to investigate the associations between IL-6 and IL-10 promoter single-nucleotide polymorphisms (SNPs) and the susceptibility to BD and their implication on plasma levels. We genotyped IL-6 −174 G/C (rs1800795) using Mutagenically Separated Polymerase Chain Reaction PCR (MS-PCR) and IL-10 −1082 G/A (rs1800896) and −819 C/T (rs1800871) using Sequence Specific Primer PCR (SSP-PCR) in 87 Egyptian patients and 97 controls. The plasma levels of IL-6 and IL-10 were measured using Enzyme-linked Immunosorbent Assay (ELISA). Significant increase in the frequency of −1082 GG genotype (P < 0.05, OR = 2.25, 95%CI = 1.03–4.91) and significant decrease in the frequency of −1082 GA genotype (P < 0.05, OR = 0.53, 95%CI = 0.29–0.96) was demonstrated in BD patients compare to controls. Patients with genital ulcer had significantly lower frequency of −1082 GG (P < 0.05, OR 0.2, 95% CI = 0.04–0.99) and G allele (P < 0.05, OR = 0.28, 95%CI = 0.08–0.93), while patients with ocular manifestations had significantly higher frequency of −1082 G allele (P < 0.01, OR = 2.28, 95%CI = 1.19–4.36). BD patients had significantly higher level of IL-6 (P < 0.001) and significantly lower level of IL-10 (P < 0.001) compared to controls. The changes in the level of cytokines were independent of any genotype of IL-6 or any genotype/haplotype of IL-10. Patients with active disease state had significantly higher level of IL-6 compared to patients in remission (P < 0.05). In conclusion, our preliminary study indicates that the polymorphism at IL-10 −1082 G/A may play a role in BD susceptibility. The significant increase in IL-6 level and the significant decrease in IL-10 level in BD patients were independent of any particular genotype in IL-6 or any particular genotype/haplotype in IL-10.     

HMGB1 and RAGE levels in induced sputum correlate with asthma severity and neutrophil percentage

Previous work indicated that high mobility group box-1 (HMGB1) protein may be involved in neutrophilic asthma. Here, we sought to investigate the correlation between HMGB1 and one of its receptors, receptor for advanced glycosylation end products (RAGE), with the severity of bronchial asthma. Compared to the control group (30 healthy individuals), patients in the asthma group (n = 72) exhibited a higher percentage of neutrophils and higher HMGB1 and RAGE levels in induced sputum samples (P < 0.05). Concurrently, FEV₁% was significantly lower in the asthma group (P < 0.05). Further, compared to mild and moderate asthma, in patients with severe asthma ACQ scores, the percentage of neutrophils, and HMGB1 levels were significantly higher, while FEV₁% was significantly lower (P < 0.05). The percentage of neutrophils and HMGB1 and RAGE levels were lower after treatment than before treatment (P < 0.05). Finally, negative correlations were observed between HMGB1 or RAGE levels and FEV₁% (r = −0.777 and r = −0.291, P < 0.05), and positive correlations were detected between HMGB1 or RAGE levels and percentage of neutrophils (r = 0.803 and r = 0.326, P < 0.05). Additionally, positive correlations were observed between HMGB1 and RAGE levels within the asthma group (r = 0.306, P < 0.05). Therefore, HMGB1 protein levels correlate with the severity of asthma, and HMGB1 may contribute to the inflammatory process of asthma.     

Renal expression of proto-oncogene Ets-1 on matrix remodeling in experimental diabetic nephropathy

The molecular mechanisms of glomerulosclerosis and tubulointerstitial fibrosis in diabetic nephropathy (DN) have received scant attention. Ets-1 proto-oncogene plays a role in matrix remodeling by regulating matrix-degrading enzymes. We investigated the possible role of Ets-1 in the pathogenesis of DN. 6-week-old male Sprague-Dawley rats were divided into two experimental groups as follows: control group (n = 30) and a Diabetes mellitus group (n = 40) induced by injection of streptozotozin (STZ). The rats were investigated at 1, 4, 8, 12 and 16 weeks after STZ-treatment. By means of immunohistochemistry, the expression of Ets-1 in glomeruli was significantly increased in STZ-treated rat kidneys from week 1 (P < 0.05) and reached the peak at week 4 (P < 0.05), followed by a downward trend at subsequent time points. Similarly, the expression of Ets-1 in the tubulointerstitium was also markedly increased from week 1 (P < 0.05) and reached a maximum at week 8 (P < 0.05). By double immunostaining, Ets-1-positive cells were frequently found to co-express matrix metalloproteinase-2 (MMP-2) in STZ-treated rat kidneys. Increased expression of tissue inhibitor of metalloproteinase-2 (TIMP-2) coincided with increased expression of α-smooth muscle actin (α-SMA) in STZ-induced DN. A positive relationship was observed between the expression of Ets-1 in glomeruli or tubulointerstitium and the expression of MMP-2 (P < 0.01; P < 0.01, respectively) in STZ-treated rat kidneys. The ratio of MMP-2 and TIMP-2 in glomeruli or tubulointerstitium was negatively correlated with deposition of type IV collagen (P < 0.01; P < 0.01, respectively). These findings suggest that Ets-1 may play a critical role in fine-tuning matrix remodeling of STZ-induced DN.     

Low-frequency H-reflex depression in trained human soleus after spinal cord injury

After spinal cord injury (SCI), widespread reorganization occurs within spinal reflex systems. Regular muscle activity may influence reorganization of spinal circuitry after SCI. The purpose of this study is to investigate the effects of long-term soleus training on H-reflex depression in humans after SCI. Seven subjects with acute (<7 weeks) SCI (AC group) underwent testing of H-reflex depression at several frequencies of repetitive stimulation. Eight subjects (including 3 from AC) stimulated one soleus muscle daily, leaving the other leg as an untrained within-subject control. Trained limb H-reflexes were assessed during year 1 (TR1) and year 2 (TR2) of training. Untrained limbs were tested during year 2 (UN). H-reflex amplitude was lower at 1, 2 and 5 Hz than at 0.1 or 0.2 Hz (p < 0.05). The pattern of depression differed between AC and UN (p < 0.05), but not between TR2 and UN (p > 0.05) despite significant adaptations in torque and fatigue resistance (p < 0.05). Three subjects who began training very early after SCI retained H-reflex post activation depression, suggesting that early intervention of daily muscular activity may be important.     

Expression of kisspeptin/GPR54 and PIBF/PR in the first trimester trophoblast and decidua of women with recurrent spontaneous abortion

Kisspeptin and its receptor GPR54 play a major role in trophoblast invasion, and progesterone-induced blocking factor (PIBF) is needed for maintaining pregnancy. The expression of kisspeptin/GPR54 and PIBF/progesterone receptor (PR) in trophoblasts and deciduas and the relationship between kisspeptin and PIBF were investigated in the same women with recurrent spontaneous abortion (RSA). Trophoblastic and decidual tissues were collected from 32 RSA women who miscarried a genetically normal fetus, and 35 women who had voluntary abortion. Kisspeptin, GPR54, PIBF and PR were investigated using immunohistochemistry. Kisspeptin, GPR54 and PIBF expressions in syncytiotrophoblasts and cytotrophoblasts were decreased in RSA women as compared to controls (P < 0.05). Kisspeptin, PIBF and PR expressions in deciduas were significantly decreased in RSA women as compared to controls (P < 0.01). GPR54 expression in deciduas nearly showed no difference between the RSA group and the control group (P = 0.958). Kisspeptin and PIBF expressions in syncytiotrophoblasts, cytotrophoblasts and deciduas were correlated with each other in the RSA group (Kappa = 0.602, P = 0.001; Kappa = 0.590, P = 0.001; Kappa = 0.392, P = 0.011). These data support the hypothesis that decreased kisspeptin and PIBF expressions in trophoblasts and deciduas are associated with RSA.     

Does maternal fermented dairy products consumption protect against cow's milk protein allergy in toddlers?

BackgroundCow's milk protein allergy (CMPA) is the most common immunoglobulin E-mediated food allergy in childhood.ObjectiveTo investigate the potential impact on the disease of the frequency, amount, and diversity of maternal consumption of fermented dairy products (FDP) during pregnancy and lactation in children with immunoglobulin E-mediated CMPA.MethodsOne hundred sixty toddlers (80 with physician-diagnosed CMPA and 80 healthy controls) and their mothers participated in this case-control study. The data were collected using a structured questionnaire and were compared between the 2 groups.ResultsThe most commonly consumed FDP were cheese, yogurt, and tarhana. The amounts of maternal yogurt, tarhana, and kefir consumed during pregnancy (P < .001, P < .001, and P = .04, respectively) in addition to yogurt and tarhana consumption during lactation (P < .001 and P = .001, respectively) were lower in toddlers with CMPA. The frequency of maternal consumption of yogurt, cheese, and tarhana during lactation (P = .001, P = .003, and P = .02, respectively) and the diversity of FDP were also lower in toddlers with CMPA (P = .001). At multivariate logistic regression analysis, maternal weight gain during pregnancy (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.04-1.18; P = .001), maternal age (OR, 1.20; 95% CI, 1.09-1.31; P < .001), and gestational age at birth (OR, 1.23; 95% CI, 1.03-1.48; P = .02) increased the odds of the baby having CMPA. The diversity of FDP consumed during lactation was protective against CMPA (OR, 0.439; 95% CI, 0.272-0.711; P = .001).ConclusionWeekly maternal consumption of FDP was low during pregnancy and lactation in toddlers with CMPA. Although the diversity of FDP consumed during lactation may reduce the risk of CMPA, this effect was not observed during pregnancy.     

Prenatal ozone exposure abolishes stress activation of Fos and tyrosine hydroxylase in the nucleus tractus solitarius of adult rat

Ozone (O₃) is widely distributed in the environment, with high levels of air pollution. However, very few studies have documented the effects on postnatal development of O₃ during pregnancy. The long-term effects of prenatal O₃ exposure in rats (0.5 ppm 12 h/day from embryonic day E5 to E20) were evaluated in the adult nucleus tractus solitarius (NTS) regulating respiratory control. Neuronal response was assessed by Fos protein immunolabeling (Fos-IR), and catecholaminergic neuron involvement by tyrosine hydroxylase (TH) labeling (TH-IR). Adult offspring were analyzed at baseline and following immobilization stress (one hour, plus two hours’ recovery); immunolabeling was observed by confocal microscopy. Prenatal O₃ increased the baseline TH gray level per cell (p < 0.001). In contrast, the number of Fos-IR cells, Fos-IR/TH-IR colabeled cells and proportion of TH double-labeled with Fos remained unchanged. After stress, the TH gray level (p < 0.001), number of Fos-IR cells (p < 0.001) and of colabeled Fos-IR/TH-IR cells (p < 0.05) and percentage of colabeled Fos-IR/TH-IR neurons against TH-IR cells (p < 0.05) increased in the control group. In prenatal-O₃ rats, immobilization stress abolished these increases and reduced the TH gray level (p < 0.05), indicating that prenatal O₃ led to loss of adult NTS reactivity to stress. We conclude that long-lasting sequelae were detected in the offspring beyond the prenatal O₃ exposure. Prenatal O₃ left a print on the NTS, revealed by stress. Disruption of neuronal plasticity to new challenge might be suggested.     

Changes in purines concentration in the cerebrospinal fluid of patients experiencing pain: A case-control study

This study analyzes the relationship between extracellular purines and pain perception in humans. Cerebrospinal fluid (CSF) levels of purines and their metabolites were compared between patients displaying acute and/or chronic pain syndromes and control subjects. The CSF levels of IMP, inosine, guanosine and uric acid were significantly increased in the chronic pain group and correlated with pain severity (P < 0.05). Patients displaying both chronic and acute pain presented similar changes in the CSF purines concentration (P < 0.05). However, in the acute pain group, only CSF inosine and uric acid levels were significantly increased (P < 0.05). These findings suggest that purines, in special inosine, guanosine and uric acid, are associated with the spinal mechanisms underlying nociception.     

Changes in body fat percentage during body weight stable conditions of increased daily protein intake vs. control

Objective

The objective of this study was to examine if increased protein intake vs. control influences body fat percentage during stable body weight.

Design

Body composition was assessed before and after a 3-month isoenergetic dietary intervention of 2MJ/d supplements exchanged with 2MJ/d of habitual ad libitum energy intake. The parallel design consisted of protein-rich supplements in the protein group (n = 12) and an isoenergetic combination of carbohydrate and fat supplements in the control group (n = 12). Daily protein intake was calculated from a 24 h urinary nitrogen. Body composition was measured by a combination of underwater-weighing technique, deuterium-dilution technique and whole-body dual-energy X-ray absorptiometry (DXA), a method that allows for estimation of 4-body compartments (fat and lean; water, bone and rest).

Results

Subjects were weight stable and did not change their habitual physical activity. Daily protein intake increased in the protein group during the intervention compared to baseline with + 11 ± 14 g (P < 0.05) vs. the control group that did not change their protein intake − 1 ± 15 g. This resulted in a significant difference in protein intake during the intervention of 80 ± 21 g of the protein group vs. 59 ± 11 g of the control group (P < 0.01). Change in body fat percentage showed a significant group × time interaction of decreased body fat percentage of − 1.0 ± 1.1% of the protein group vs. 0.1 ± 0.6% of the control group (P < 0.05). The group × time interaction of change in fat mass was significant (P < 0.05), and change in fat-free mass was a trend (P = 0.05). Fat-free mass of the protein group had increased with + 0.9 ± 0.6 kg (P < 0.01), and fat mass had decreased with − 0.6 ± 0.8 kg (P < 0.05), while the control group had not changed.

Conclusion

During increased daily protein intake vs. control body fat percentage decreased with unchanged physical activity during 3 months of stable body weight.     

Long-lasting resistance to haloperidol-induced catalepsy in male rats chronically treated with caffeine

Chronic caffeine consumption has been inversely associated with the risk of developing Parkinson's disease. Here we assessed whether chronic caffeine treatment increases the resistance of male Wistar rats to haloperidol (1 mg/kg, s.c.)-induced catalepsy, measured in the bar test at 15 min intervals during 3 h. Caffeine (5 mg/kg/day) was delivered for 6 months via drinking water. Control rats received only tap water. Treatments began when animals were 3–4 months old. In order to unveil long-lasting catalepsy refractoriness not attributable to the presence of caffeine in the brains of rats, they were evaluated from day 18 to day 27 after caffeine withdrawal, a time that is far in excess for the full excretion of a caffeine dose in this species. The average cataleptic immobility measured in caffeine-treated rats (n = 23) was 1148 ± 140 s, a value 34 ± 8% lower than that recorded in control animals (n = 20), whose mean immobility was 1736 ± 137 s (P = 0.0026, t-test). The percentage of catalepsy reduction measured in caffeine-treated rats evaluated on days 18–20 after caffeine discontinuation (−32 ± 13%, n = 12, P < 0.05) was comparable to the catalepsy decrease recorded in those animals tested on days 21–27 (−36 ± 10%, n = 11, P < 0.02), a finding compatible with the notion that the effect was indeed mediated by enduring changes of brain functioning and not by the physical presence of caffeine or its metabolites. Caffeine-treated rats also had higher catalepsy latency scores compared with control rats (P < 0.01, U-test). The present findings show that chronic consumption of caffeine produces perdurable resistance to catalepsy induced by dopamine receptor blockade, possibly through enhancement of dopamine transmission, giving further support to the epidemiological results indicating that prolonged caffeine consumption affords neuroprotection against Parkinson's disease.     

Protein intake induced an increase in exercise stimulated fat oxidation during stable body weight

Background

Protein-rich weight-loss diets spare fat-free mass at the cost of fat mass. The objective was to examine if there is a change in stimulated fat oxidation related to protein intake during stable body weight.

Methods

Subjects' (BMI 22 ± 2 kg/m², age 25 ± 8 years) maximal fat oxidation (Fat_max) was assessed during a graded bicycle test, before and after a 3-month dietary-intervention of 2 MJ/day supplements exchanged with 2 MJ/d of habitual energy intake. The parallel design consisted of protein-rich supplements in the protein group and an isocaloric combination of carbohydrate and fat supplements in the control group. Daily protein intake was determined according to 24-h urine nitrogen. Body composition was measured according to a 4-compartment model by a combination of underwater-weighing technique, deuterium-dilution technique and whole-body dual-energy X-ray absorptiometry (DXA).

Results

Subjects were weight stable and did not change their physical activity. The protein group (n = 12) increased protein intake (11 ± 14 g, P < 0.05) and had significantly higher daily protein intake vs. control (n = 4) (80 ± 21 vs.59 ± 11 g, P < 0.05). Fat_max increased significantly in the protein group (0.08 ± 0.08 g/min, P < 0.01). Fat-free mass increased independent of change in body weight (P < 0.01), and fat mass and fat percentage decreased (P < 0.05). Change in Fat_max was a function of change in protein intake (r = 0.623, P < 0.05), and not of changes in body composition or VO₂max.

Conclusion

Increased stimulated fat oxidation was related to increased protein intake.     

Heme oxygenase–carbon monoxide pathway is involved in regulation of respiration in medullary slice of neonatal rats

Carbon monoxide (CO) is a novel biological messenger molecule. It is well known that CO can be synthesized in mammalian cells. In addition, CO is also demonstrated to participate in many physiological processes, such as vasomotion, thermoregulation and respiratory regulation. The purpose of our present study was to investigate the role of heme oxygenase–carbon monoxide (HO–CO) pathway in central regulation of respiration. The experiments were carried out on the medullary slices of neonatal Sprague–Dawley rats. The discharge activity of the hypoglossal rootlets was recorded to indicate the central rhythmic respiratory activity and its duration (DD), interval (DI), frequency (DF) and integrated amplitude (IA) were analyzed. The slices were perfused with ZnPP-9 (a potent inhibitor of heme oxygenase), CO and hemin (substrate of heme oxygenase), respectively, to observe their effects on respiratory activity. The results obtained were as follows: ZnPP-9 could decrease DD, DI and IA, and increase DF (P < 0.05); exogenous CO caused a decrease in DD and DF, and an increase in DI and IA (P < 0.05); in response to hemin, DI and IA decreased, DF increased (P < 0.05), and DD did not change significantly (P > 0.05); administration of both ZnPP-9 and hemin could decrease DI, and increase DF (P < 0.05), but did not affect DD and IA significantly (P > 0.05). It can be concluded from the results above that the HO–CO pathway may be involved in the regulation of rhythmic respiration at the level of medulla oblongata.     

Daytime modulation of cortical spreading depression according to blood glucose levels

The aim of this study was to investigate the effects of daytime and blood glucose levels on the propagation of cortical spreading depression (SD). Thirty-nine male Wistar rats were used. Animals were housed 5 per cage with a 12-h, light–dark cycle (lights on at 0600 h). Food and water were available ad libitum, and animals were fasted the night before the experiments. Cortical SD was recorded continuously for 3 h using Ag–AgCl agar-Ringer electrodes placed on the parietal cortex. Every 20 min, SD was elicited by 2% KCl stimulation of the frontal cortex for 1 min. After 1 h of SD-recording, blood glucose levels were measured, and animals were injected intravenously either with glucose (40% solution, 1 mL), insulin (0.3 U/100 g of body weight), or mannitol (20% solution, 1 mL). In the middle of the light period, which corresponds to zeitgeber time (ZT)5, 8 animals received glucose, 7 received insulin, and 6 received mannitol. In another experimental set, glucose or insulin was administered at ZT12 (at the end of the light period); 12 rats received glucose, and 6 received insulin. All the animals that received glucose were hyperglycaemic (P < 0.01), and the hyperglycaemia was less pronounced in the ZT12 group (P < 0.05; Student's t-test). Insulin induced acute hypoglycaemia in animals of both groups (ZT5, P < 0.02; ZT12, P < 0.05; Student's t-test). Glucose injection at ZT5 reduced SD, whereas the insulin ZT5 group showed increased SD propagation (ANOVA, P < 0.05 and 0.01, respectively). Neither glucose nor insulin injection changed SD velocity at ZT12. We concluded that blood glucose levels change the velocity of SD propagation and that these effects are influenced by the daytime. Dark periods seemed to produce a resistance to cortical SD propagation.