Effects of unilateral decortication on β-adrenergic receptors in the remaining cortex and in the hypothalamus of female rats

Many experiments have been performed to evaluate the physiological role of catecholaminergic mechanisms of gonadotropin release. The purpose of the present study was to determine the concentration of β-adrenoreceptors in the remaining (right) cerebral cortex and in right and left hypothalamic halves of hemi-decorticated female rats which exhibited elevated plasma gonadotropin levels as observed previously. The density of β-receptors was measured using a high-affinity β-adrenergic ligand, iodocyanopindolol (ICYP). Scatchard estimates were obtained for maximum binding (B(max) fmol/mg of tissues) from pooled cerebral cortical and hypothalamic tissue of animals under several experimental conditions after hemi-decortication and sham operation. There was an increase in β-adrenoreceptor density in the remaining (right) cerebral cortex at all times examined in hemi-decorticate in comparison with the sham-operated animals (7 days, +10.9%; 21 days, +8.4%; 90 days, +22%; and 90 days plus ovariectomy, +34.8%). The number of β-adrenoreceptors in the right hypothalamic half in hemi-decorticates decreased at 21 days (-42.20%) and then increased at 90 days (+76.63%) and 90 days plus ovariectomy (+51.75%) when compared with the left hypothalamic half. At the same time there were no significant changes in the sham-operated animals when comparing the receptor density in the right and left hypothalamic halves, respectively. Thus, our results suggest a direct adrenergic pathway by which the left cortex can influence the right cortex and a crossed pathway to the contralateral hypothalamus changing adrenergic activity which can alter the β-adrenergic receptor binding capacity in the hypothalamus.

Toxic effects of leaves of Ricinus communis (Euphorbiaceae) to laboratory nests of Atta sexdens rubropilosa (Hymenoptera: Formicidae)

Laboratory nests of the leaf-cutting ant Atta sexdens rubropilosa Forel fed daily with leaves of Ricinus communis showed a gradual decrease in fungal garden volume, a higher ant mortality rate, and fungal garden extinction after 6 weeks. The mean oxygen consumption rate of these ants was higher than that of control ants collected from nests fed with leaves of Eucalyptus alba (Myrtaceae) suggesting one or more components of the leaves of R. communis had a direct physiological effect on the ants, in addition to inhibiting fungal garden growth.

Effects of Chronic Physical Activity and of Ultrasound Treatment on Bone Consolidation

The objective of this study was to investigate the effects of ultrasound treatment and physical exercise on the velocity of bone consolidation and resistance to deformation. We performed osteotomy in the upper third of the right tibia of rats. Physical training consisted of swimming 1 h per day with a load of 5% b.w. for 30 days. Therapy with medium-intensity ultrasound was applied daily on the damaged area. Wistar rats were divided into the following groups: osteotomized sedentary animals with no ultrasound treatment (1.OSnUS), osteotomized trained animals with no ultrasound treatment (2.OTnUS), osteotomized sedentary animals with ultrasound treatment (3.OSwUS). and osteotomized trained animals with ultrasound treatment (4.OTwUS). The animals were sacrificed for the following analyses: muscle glycogen, serum alkaline phosphatase at the 5th, 10th, 20th, and 30th days, test of maximum resistance to flexion, rupture flexion and mean tibial rigidity at the 30th day. Muscle glycogen was increased at the 20th day: alkaline phosphatase was elevated at the 5th and 20th days in groups 3.OSwUS and 4.OTwUS. and decreased at the 10th day. Groups1.OSnUS and 2.OTnUS did not show significant variations. In the mechanical resistance tests, we noted that ultrasound therapy and the association of physical activity used in the present study showed significant differences in bone resistance and bone rigidity after 30 days of treatment. These facts suggest that ultrasound or physical activity, or their combination may accelerate the process of bone tissue repair.

Energetic and physiological correlates of prey handling and ingestion in lizards and snakes

In this review, we summarize the energetic and physiological correlates of prey handling and ingestion in lizards and snakes. There were marked differences in the magnitude of aerobic metabolism during prey handling and ingestion between these two groups, although they show a similar pattern of variation as a function of relative prey mass. For lizards, the magnitude of aerobic metabolism during prey handling and ingestion also varied as a function of morphological specializations for a particular habitat, prey type, and behavior. For snakes, interspecific differences in aerobic metabolism during prey handling seem to be correlated with adaptations for prey capture (venom injection vs. constriction). During ingestion by snakes, differences in aerobic metabolism might be due to differences in cranial morphology, although allometric effects might be a potentially confounded effect. Anaerobic metabolism is used for prey handling and ingestion, but its relative contribution to total ATP production seems to be more pronounced in snakes than in lizards. The energetic costs of prey handling and ingestion are trivial for both groups and cannot be used to predict patterns of prey-size selection. For lizards, it seems that morphological and ecological factors set the constraints on prey handling and ingestion. For snakes, besides these two factors, the capacity of the cardio-respiratory system may also be an important factor constraining the capacity for prey handling and ingestion. © 2001 Elsevier B.V.

Protein Deficiency Attenuates the Effects of Alloxan on Insulin Secretion and Glucose Homeostasis in Rats

We have investigated the effect of alloxan on insulin secretion and glucose homeostasis in rats maintained on a 17% protein (normal protein, NP) or 6% protein (low protein, LP) diet from weaning (21 days old) to adulthood (90 days old). The incidence of alloxan diabetes was higher in the NP (3.5 times) than in the LP group. During an oral glucose tolerance test, the area under serum glucose curve was lower in LP (57%) than in NP rats while there were no differences between the two groups in the area under serum insulin curve. The serum glucose disappearance rate (Kitt) after exogenous insulin administration was higher in LP (50%) than in NP rats. In pancreatic islets isolated from rats not injected with alloxan, acute exposure to alloxan (0.05 mmol/L) reduced the glucose- or arginine-stimulated insulin secretion of NP islets by 78% and 56%, respectively, whereas for islets from LP rats, the reduction was 47% and 17% in the presence of glucose and arginine, respectively. Alloxan treatment reduced the glucose oxidation in islets from LP rats to a lesser extent than in NP islets (23% vs. 56%). In conclusion, alloxan was less effective in producing hyperglycemia in rats fed a low protein diet than in normal diet rats. This effect is attributable to an increased peripheral sensivity to insulin in addition to a better preservation of glucose oxidation and insulin secretion in islets from rats fed a low protein diet.

Influence of angiotensin II receptor subtypes of the paraventricular nucleus on the physiological responses induced by angiotensin II injection into the medial septal area

Objective - We determined the effects of losartan and PD 123319 (antagonists of the AT1 and AT2 angiotensin receptors, respectively), and [Sar1, Ala8] ANG II (a relatively peptide antagonist of angiotensin receptors) injected into the paraventricular nucleus (PVN) on water and 3% NaCl intake, and the diuretic, natriuretic, and pressor effects induced by administration of angiotensin II (ANG II) into the medial septal area (MSA) of conscious rats. Methods - Holtzman rats were used. Animals were anesthetized with tribromoethanol (20 mg) per 100 grams of body weight, ip. A stainless steel guide cannula was implanted into the MSA and PVN. All drugs were injected in 0.5-μl volumes for 10-15 seconds. Seven days after brain surgery, water and 3% NaCl intake, urine and sodium excretion, and arterial blood pressure were measured. Results - Losartan (40 nmol) and [Sar1, Ala8] ANG II (40 nmol) completely eliminated whereas PD 123319 (40 nmol) partially blocked the increase in water and sodium intake and the increase in arterial blood pressure induced by ANG II (10 nmol) injected into the MSA. The PVN administration of PD 123319 and [Sar1, Ala8] ANG II blocked whereas losartan attenuated the diuresis and natriuresis induced by MSA administration of ANG II. Conclusion - MSA involvement with PVN on water and sodium homeostasis and arterial pressure modulation utilizing ANGII receptors is suggested.

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram)

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and waterrfeed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32°C in 30 min, 32 to 36°C in 30 min, 36 to 37°C in 15 min, and 37 to 41°C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 ± 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB O decreased blood Na and K, and DEB O and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB O and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

Mitigating stress effects during transportation of matrinxã(Brycon amazonicus Günther, 1869; Characidae) through the application of calcium sulfate

This study verified the effects of CaSO4 on physiological responses of the tropical fish matrinxãBrycon amazonicus(200.2 ± 51.1 g) in water containing CaSO4 after a 4-h transportation at concentrations of: 0, 75, 150, and 300 mg L-1. Blood samples were collected prior to transportation (initial levels), immediately after packaging, at arrival, and 24 h and 96 h after transportation (recovery). Cortisol levels increased after ackaging (118.2 ± 14.2 ng ml-1), and decreased slightly after transportation in water containing CaSO4 (106.8 ± 14.1), but remained higher than initial levels (21.0 ± 2.6 ng ml)1). Fish kept at 150 mg L-1 CaSO4 reached the pre-transportation levels at 24 h of recovery. Blood glucose increased after transportation in all treatments (8.2 ± 0.2 mmol L-1) and declined after full recovery to values below initial levels (4.8 ± 0.1 mmol L-1). Chloride levels did not change in CaSO4 treatments; serum sodium concentrations decreased after packaging and after transportation. Serum calcium levels did not differ among treatments, but decreased after packaging and increased at 96 h of recovery. Hematocrit and the number of red blood cells were higher in all treatments after packaging and arrival, except in fish exposed to 300 mg L-1 CaSO4. Mean corpuscular volume increased in 75 mg L-1 CaSO4, which reached the higher VCM after transportation. Hemoglobin levels increased only after transportation, regardless of calcium sulfate levels. Handling before transportation and transportation itself were both stressful to fish; calcium sulfate at concentrations tested in the present work had a moderate influence in the reduction of stress responses. © 2009 Blackwell Verlag, Berlin.

Monitoring chronic physical stress using biomarkers, performance protocols and mathematical functions to identify physiological adaptations in rats

This study was undertaken to characterize the effects of monotonous training at lactate minimum (LM) intensity on aerobic and anaerobic performances; glycogen concentrationsin the soleus muscle, the gastrocnemius muscle and the liver; and creatine kinase (CK), free fatty acids and glucose concentrations in rats. The rats were separated into trained (n =10), baseline (n = 10) and sedentary (n=10) groups. The trained group was submitted to the following: 60 min/day, 6 day/week and intensity equivalent to LM during the 12-week training period. The training volume was reduced after four weeks according to a sigmoid function. The total CK (U/L) increased in the trained group after 12 weeks (742.0±158.5) in comparison with the baseline (319.6±40.2) and the sedentary (261.6+42.2) groups. Free fatty acids and glycogen stores (liver, soleus muscle and gastrocnemius muscle) increased after 12 weeks of monotonous training but aerobic and anaerobic performances were unchanged in relation to the sedentary group. The monotonous training at LM increased the level of energy substrates, unchanged aerobic performance, reduced anaerobic capacity and increased the serum CK concentration; however, the rats did not achieve the predicted training volume.

Synthesis and evaluation of diethylethylamine-chitosan for gene delivery: Composition effects on the in vitro transfection efficiency

Chitosan has been indicated as a safe and promising polycation vector for gene delivery. However its low transfection efficiency has been a challenging obstacle for its application. To address this limitation, we synthesized chitosan derivatives which had increasing amounts of diethylethylamine groups (DEAE) attached to the chitosan main chain. The plasmid DNA VR1412 (pDNA), encoding the ß-galactosidase (ß-gal) reporter gene was used to prepare nanoparticles with the chitosan derivatives, and the transfection studies were performed with HeLa cells. By means of dynamic light scattering and zeta potential measurements, it was shown that diethylethylamine-chitosan derivatives (DEAEx-CH) were able to condense DNA into small particles having a surface charge depending on the polymer/DNA ratio (N/P ratio). Nanoparticles prepared with derivatives containing 15 and 25% of DEAE groups (DEAE15-CH and DEAE25-CH) exhibited transfection efficiencies ten times higher than that observed with deacetylated chitosan (CH). For derivatives with higher degrees of substitution (DS), transfection efficiency decreased. The most effective carriers showed low cytotoxicity and good transfection activities at low charge ratios (N/P). Vectors with low DS were easily degraded in the presence of lysozyme at physiological conditions in vitro and the nontoxicity displayed by these vectors opens up new opportunities in the design of DEAE-chitosan-based nanoparticles for gene delivery. © 2013 IOP Publishing Ltd.

Effects of Chronic Stress and Alendronate Therapy on the Osseointegration of Titanium Implants

Purposes: The purposes of this study were to evaluate the influence of chronic stress (CS) on implant osseointegration and also to analyze whether alendronate (ALN) therapy could prevent these eventual stress-negative effects. Materials and Methods: Adult male Holtzmann rats were assigned to one of the four experimental groups: AL (ALN; 1mg/kg/week; n=12), ALS (ALN+CS; 1mg/kg/week; n=12), CTL (sterile physiological saline; n=12), or CTLS (sterile physiological saline+CS; n=12). After 58 days of drug therapy, the ALS and CTLS groups were exposed to CS, and 2 days later all animals underwent tibial implant installation. The animals were euthanized 28 days following the operative surgical procedure. Results: It was observed that the CTLS group presented an impairment of bone metabolism represented by lowest levels of bone-specific alkaline phosphatase and bone area fraction occupancy values. Furthermore, these animals presented a higher proportion of empty osteocytic lacunae. In contrast, the ALN therapy showed increased osseointegration and torque value parameters, regardless of stress exposition. Conclusions: Analysis of the data presented suggests that CS partially impairs the osseointegration of tibial implants and that ALN therapy is able to prevent these negative effects. © 2013 Wiley Periodicals, Inc.

Effect of shade and water sprinkling on physiological responses and milk yields of Holstein cows in a semi-arid region

The effects of shading and water sprinkling on physiological responses and milk production were studied in Holstein cows managed in an equatorial semi-arid region. Five cows were observed for 36 days during May and June 2009. We studied the effects of sun, shade, shade plus single sprinkling, shade plus sprinkling every 2. h and shade plus sprinkling every hour on physiological responses, i.e., rectal temperature, coat surface temperature and respiratory rate, and on milk production. Environmental variables, i.e., air temperature, black globe temperature, mean radiant temperature, relative humidity and wind speed, were recorded every 30. min throughout the observation period. The statistical analysis utilized a 5×5 replicated latin square, and the results showed reduced values in physiological variables in cows that were protected from short wave radiation and that received water sprinkling; milk yield increased by approximately 3.5. kg in such animals relative to those not receiving such treatment. However, the milk yield for the morning milking presented similar mean values regardless of whether the animals received shading and sprinkling benefits, which indicates that frequency of sprinkling and amount of time (permanence) in the shade were critical for the effect on milk yield. © 2013 Elsevier B.V.

Effects of corn replacement by sorghum in broiler diets on performance and intestinal mucosa integrity

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Physiological adaptations during endurance training below anaerobic threshold in rats

To assess the effects of continuous exercise training at intensities corresponding to 80 and 90 % of the lactate minimum test (LM), we evaluated antioxidant activity, hormone concentration, biochemical analyses and aerobic and anaerobic performance, as well as glycogen stores, during 12 weeks of swimming training in rats. One-hundred rats were separated into three groups: control (CG, n = 40), exercise at 80 (EG80, n = 30) and 90 % (EG90, n = 30) of LM. The training lasted 12 weeks, with sessions of 60 min/day, 6 days/week. The intensity was based at 80 and 90 % of the LM. The volume did not differ between training groups (Ẋ of EG80 = 52 ± 4 min; Ẋ of EG90 = 56 ± 2 min). The glycogen concentration (mg/100 mg) in the gastrocnemius increased after the training in EG80 (0.788 ± 0.118) and EG90 (0.795 ± 0.157) in comparison to the control (0.390 ± 0.132). The glycogen stores in the soleus enhanced after the training in EG90 (0.677 ± 0.230) in comparison to the control (0.343 ± 0.142). The aerobic performance increased by 43 and 34 % for EG80 and EG90, respectively, in relation to baseline. The antioxidant enzymes remain unchanged during the training. Creatine kinase (U/L) increased after 8 weeks in both groups (EG80 = 427.2 ± 97.4; EG90 = 641.1 ± 90.2) in relation to the control (246.9 ± 66.8), and corticosterone (ng/mL) increased after 12 weeks in EG90 (539 ± 54) in comparison to the control (362 ± 44). The continuous exercise at 80 and 90 % of the LM has a marked aerobic impact on endurance performance without significantly biomarkers changes compared to control. © 2013 Springer-Verlag Berlin Heidelberg.