Effect of Exercise Repetitions on Arylesterase Activity of PON1 in Plasma of Average-Trained Men-The Dissociation between Activity and Concentration.

Exercise may increase the antioxidant capacity of plasma by stimulating antioxidant enzymes. The study aimed to measure the effect of three repetitions of acute exercise on arylesterase (ARE) activity of the paraoxonase 1 (PON1) enzyme. Eleven average-trained men (age 34.0 ± 5.2 years) completed three treadmill runs. ARE activity in plasma was evaluated spectrophotometrically and compared with PON1 concentration (PON1c), paraoxonase (PON) activity, and high-density lipoprotein cholesterol (HDL-C) at rest and after exercise. In all repetitions of the exercise, ARE activity remained stable, and ARE activity standardized for PON1c (ARE/PON1c) was lower post- than pre-exercise. The ARE/PON1c ratio changes returned to baseline levels during rest after each exercise session. Pre-exercise ARE activity correlated negatively with post-exercise C-reactive protein (CRP) (ρ = -0.35, p = 0.049), white blood cell count (WBC) (ρ = -0.35, p = 0.048), polymorphonuclear leukocytes (PMN) (ρ = -0.37, p = 0.037), and creatine kinase (CK) (ρ = -0.37, p = 0.036). ARE activity may be depleted under conditions of oxidative stress, as increases in PON1c during acute exercise did not result in parallel increases in ARE activity. No adaptation of the response of ARE activity to exercise was detected in subsequent exercise sessions. Individuals with lower pre-exercise ARE activity may develop a higher inflammatory response to strenuous exercise.

Repetitions of Strenuous Exercise Consistently Increase Paraoxonase 1 Concentration and Activity in Plasma of Average-Trained Men.

OBJECTIVES: Oxidative stress, induced by physical activity, may stimulate the expression, release, and activity of certain antioxidant enzymes. We investigated the effect of three repeated bouts of strenuous exercise on paraoxonase 1 concentration (PON1c) and paraoxonase activity (PON). METHODS: Eleven average-trained healthy men (age 34.0 ± 5.2 years) performed three strenuous exercise tests on a treadmill separated by 72 hours periods of resting. PON1c, PON, ferric-reducing activity of plasma (FRAP), lipid profile, C-reactive protein concentration (CRP), and lactate concentration were determined in plasma. RESULTS: Each exercise bout resulted in similar PON1c, PON, FRAP, and high-density lipoprotein concentration (HDL-C) increments, while PON/HDL-C ratio remained stable in all repetitions. Percentage increments at the bout of each exercise were higher for PON1c (by 64.82% at the first, by 92.9% at the second, and by 77.02% at the third exercise) than for PON (by 6.49% at the first, 10.06% at the second, and by 12.32% at the third exercise). Association was found between preexercise PON and PON1c (r = 0.56, p = 0.029), pre- (r = 0.87, p = 0.00003) and postexercise HDL-C (r = 0.6, p = 0.0002), preexercise PON and cardiovascular fitness level of participants measured as VO2max (r = 0.39, p = 0.026), and postexercise PON and lactate concentration (r = 0.44, p = 0.01). CONCLUSIONS: PON1c and PON increase during strenuous exercise, yet the effect of exercise on PON1 concentration is more pronounced. PON1 does not show tolerance to physical activity. The enzyme may provide short-term protection from oxidative stress in each exercise bout. PON may depend on exercise load. Cardiovascular fitness levels may be associated with PON1 activity.

Aerobic training modulates the effects of exercise-induced oxidative stress on PON1 activity: a preliminary study.

The aim of the study was to compare the effect of maximal exercise (ME) on paraoxonase (PON) and arylesterase (ARE) activity depending on lifestyle in respect to physical activity. The study was performed on 46 young men divided into two groups: sedentary (S) and physically active (PA). All participants performed ME on a treadmill. PON1 activities, FRAP, uric acid, bilirubin, TBARS, and lipid profile were determined in their blood before, at the bout of, and after ME. No significant differences in PON1 activities were found between S and PA subjects at baseline. Nearly all biochemicals increased at ME in both groups. Both PON and ARE activity increased at the bout of ME in PA subjects and only ARE activity in S subjects. ARE/HDL-C ratio increased at the bout of ME in PA and S subjects. The difference in PON1 activity response to ME between study groups may be a result of adaptation of PA subjects to regular physical activity. We suggest that PON1 activity may be a marker of antioxidant protection at ME and an indicator of adaptation to exercise.

Influence of different kind of clothing material on selected cardiovascular, respiratory and psychomotor parameters during moderate physical exercise.

OBJECTIVES: The aim of the experiment was to analyze the influence that the clothing material may have on human physiology and thermal comfort both at rest and physical effort to answer the question which fabric is better, a natural or a synthetic one. MATERIALS AND METHODS: We measured some psychomotor parameters: critical flicker frequency (CFF), reaction time to auditory/visual stimuli (RT), concentration of attention (CA); cardiovascular parameters: blood pressure (BP), heart rate (HR) and respiratory parameters: tidal volume (VT), minute ventilation (VE), oxygen consumption (VO2), carbon dioxide output (VCO2), respiratory exchange ratio (RER) in human volunteers before, during and after physical effort. The subjects performed a 15-min treadmill test on treadmill wearing clothes made of two different materials: 100% coarse wool and 100% acrylic. An interview was conducted directly before the exercise test to assess the subjects' general mood and wellbeing on that day. Besides, before and after the test, the subjects in their own words described the sensation they felt with respect to the physiological comfort of particular clothing. RESULTS: The results showed that wearing clothes made of different fabrics had some influence on the cardiovascular and respiratory parameters during physical effort but it did not have any effect on the psychomotor skills. The perception of physiological comfort by the subjects wearing coarse wool or acrylic depended on their physiological state and differed at rest and after the physical effort. CONCLUSIONS: The course of physiological processes depends on the kind of clothing a given person is wearing. It is not possible to clearly define which of the two clothing materials: natural - wool, or synthetic - acrylic is better. Each of them exerts a different effect on the human organism. The usefulness of a given type of clothing material seems to depend on the human physiological state and the related thermoregulatory processes.

The role of genetic (PON1 polymorphism) and environmental factors, especially physical activity, in antioxidant function of paraoxonase.

Paraoxonase 1 (PON1) is a member of a three-gene family (PON1, PON2, and PON3). PON1 activity dominates in human plasma. It is secreted from hepatic cells and is found in the circulation bound to high-density lipoproteins (HDLs). For many years it has been known only for its ability to hydrolyze organophosphate derivatives. More recently, PON1's antioxidant activity draws attention as the enzyme was described to prevent oxidation of lipoproteins by reactive oxygen species formed during oxidative stress. PON1 was also shown to hydrolyze atherogenic products of oxidative lipid modification such as phospholipid peroxides and cholesterol ester hydroperoxides. Some studies indicate that the enzyme presents a lipolactonase activity and hydrolyzes homocysteine thiolactone (HCTL). There is growing evidence as to PON1's protective role in atherosclerosis. Genetic (PON1 polymorphism) and environmental factors and lifestyle may influence PON1 blood concentration and biological activity. Among the many recognized factors accounting for lifestyle, physical activity plays an important role. Various, often opposite, effects on PON1 status are observed in regular training and single physical activities. The results of different studies are often contradictory. It may depend on the time, intensity, and frequency of physical activity. Additionally, it seems that the effects of physical activity on PON1 blood concentration and activity are modified by environmental and lifestyle factors as well as PON1 polymorphism.

Influence of thyrotropin-releasing hormone (TRH) dialyzed into the hippocampus on memory processes in rabbit.

There are conflicting reports on the influence of thyrotropin-releasing hormone (TRH) on the process of learning. We decided to study this problem using the paradigm of classical eyeblink conditioning as the animal model of learning processes. During the extinction training TRH in its natural form of pG1uTRH was applied into the rabbit hippocampus through a chronically implanted microdialysis probe. A Glu(1)TRH, analog with less biological potency than TRH as the control of specificity for TRH and a 0.9% NaCl solution as the control for both substances were applied by the same way as pGluTRH. We found that pGluTRH extended the process of extinction and enhanced the further acquisition of the reflex. The analog of TRH, Glu(1)TRH, was ineffective. Finally, it may be stated that TRH acting in the hippocampus prolonged process of forgetting and improved succeeding learning. The effect was specific and long lasting.

Microdialysis of the brain structures: application in behavioral research on vasopressin and oxytocin.

In vivo microdialysis allows sampling of brain regions in conscious, freely moving animals. Moreover, the in vivo microdialysis allows to administer drugs directly into specific brain areas. Both are useful in behavioral studies. The subject of this review is the methodology of brain microdialysis, that is construction of the probe, effect of temperature, composition of the perfusion medium, perfusion flow rate, characteristics of the membrane material and the role of the diffusion coefficient. Other techniques of the study of in vivo release, alternative for microdialysis, are described. Advantages and disadvantages of acute and chronic microdialysis are discussed. Chronic microdialysis is especially needed in behavioral studies. Finally, the examples of application of microdialysis in behavioral studies of vasopressin (AVP) and oxytocin (OXT) and our own experience in these studies are described.

Effect of excitatory amino acids on activity of vasopressinergic and oxytocinergic neurons.

A few compounds function as the excitatory amino acid (EAA) transmitters in the central nervous system (CNS), but glutamate (Glu) is the most important. Data on Glu participation in the control of vasopressinergic (AVP-ergic) and oxytocinergic (OXT-ergic) neuronal activity have been collected mainly on the basis of observations of hypothalamic AVP-ergic and OXT-ergic neurons. In vivo and in vitro experiments have demonstrated that Glu enhances bioelectric activity of the aforementioned neurons and increases AVP and OXT release. However, inhibitory effect of Glu on AVP-ergic neurons, mediated by local GABA-ergic interneurons, is also possible. Both ionotropic and metabotropic receptors participate in EAA effect on AVP-ergic and OXT-ergic neurons. EAA involvement in AVP and OXT release after osmotic stimuli and in OXT release during the milk ejection reflex has been demonstrated. Recent findings demonstrated that EAA enhanced AVP release into the extracellular fluid of hippocampus in the rabbit.

Centrally applied oxytocin has no effect on eyelid conditioning in rabbits.

OBJECTIVE: The classically conditioned rabbit eyelid reflex has proven to be useful for studying memory processes. The role of oxytocin (OXT) dialyzed into the hippocampus or caudate nucleus in the acquisition and extinction of this reflex was investigated. METHODS: Microdialysis probes were unilaterally, chronically, alternatively implanted into the mentioned brain structures. OXT was repeatedly dialyzed into each brain structure during the extinction of the conditioned eyelid reflex. An air puff was applied as an unconditioned and the tone as a conditioned stimulus to create conditioned eyelid reflex. Eyelid responses were detected by opto-electronic sensor and recorded. Thus obtained conditioned responses were calculated as a percentage of all 120, daily applied, trials of stimuli. ANOVA was used for statistical evaluation. RESULTS: Neither OXT dialyzed into the hippocampus nor into the caudate nucleus significantly changed the course of acquisition and extinction of the conditioned eyelid reflex. However, some tendency to the impairment of forgetting when dialyzed into the hippocampus and to its facilitation during caudate nucleus dialysis was observed. CONCLUSION: Conditioning of the eyelid reflex applied as the experimental model for the study of the memory processes did not show OXT participation in these processes neither in the hippocampus nor in the caudate nucleus, but this problem needs to be further studied.