Is health promotion in sports clubs associated with adolescent participants' fruit and vegetable consumption?

BACKGROUND: Although sports clubs' potential for health promotion is acknowledged, research on whether they promote healthy eating is limited. We aimed to evaluate Finnish youth sports clubs' health promotion orientation, as well as associations between sports clubs' health promotion orientation, coaches' nutritional discussions and sports club participants' (SPs') fruit and/or vegetable consumption. METHODS: The cross-sectional study included 554 SPs aged 14-16 years, 275 club officials and 311 coaches. Participants replied to questionnaires about sports clubs' health promotion and their own health behaviours, including dietary habits. Health promotion orientation was estimated using a Health Promoting Sports Club (HPSC) index (range 0-22) and nutritional discussions and fruit and/or vegetable consumption as frequencies. A mixed-effects multivariable logistic regression was used to analyse the associations. RESULTS: Most sports clubs (69%) had a high health promotion orientation, but the variation between the clubs was wide (HPSC index range 5-21). SPs' daily fruit and/or vegetable consumption was associated with female gender [odds ratio (OR) 3.48, 95% confidence interval (CI) 2.23-5.42, P < 0.001], better self-rated health (OR 3.26, 95% CI 1.13-9.41, P = 0.03), higher average school grades (OR 1.67, 95% CI 1.04-2.67, P = 0.03), and SPs' responses that their coach had often discussed nutrition (OR 2.11, 95% CI 1.41-3.14, P < 0.001). CONCLUSION: Although sports clubs' orientation towards health promotion was mostly high, it seems not to be enough to promote healthy eating among adolescent participants. Instead, coaches' nutritional discussions were associated with adolescents' fruit and/or vegetable consumption.

Sports and exercise medicine clinic in public hospital settings: a real-life concept and experiences of the treatment of the first 1151 patients.

OBJECTIVE: Physical exercise has been shown to have a variety of health-promoting effects, including improvements in cardiorespiratory and muscular fitness, symptoms and risk factors such as LDL and HDL cholesterol, triglyceride and glycosylated hemoglobin concentrations. Regular physical exercise may slow down or even reverse the progression of various non-communicable diseases (NCDs). Despite the overwhelming evidence, physical exercise is not comprehensively used as a treatment component either in primary care or in hospital settings. METHODS: The outpatient Sports and Exercise Medicine Clinic (SEMC) is the first specialized clinic in Finland to use physical exercise as a part of the public health care system. Patients needing specialist attention due to NCDs, usually combined with sedentary lifestyles, are referred to the clinic. RESULTS: The prerequisites for patient referral are the known efficacy of physical exercise intervention in the treatment of disease and the need for sports and exercise medicine expertise. The focus of the clinic is to implement physical activity into daily life with other health-promoting habits such as diet, rest and the reduction of substance use. In addition, SEMC promotes the inclusion of physical exercise in several local treatment guidelines in the hospital district. The advisory treatment protocol of SEMC consists of a baseline evaluation, face-to-face visits with a physician and/or physiotherapist at 3, 6 and 9-12 months, and contacts via phone between hospital visits. Laboratory tests, body composition, walking tests, and measurements of muscle strength and balance are performed at baseline, and body composition and physical tests are repeated after 6 and 9-12 months. CONCLUSIONS: At the core of the treatment is individualization, using motivational interviewing, considering the patients' personal interests and resources, and encouraging the patient to be an active member of our multi-professional team. We reported the first results in the SEMC with future development plans for the clinic.

Factors associated with body size perception among adolescent goal-oriented sports participants and non-participants: a cross-sectional Finnish study.

BACKGROUND: Regardless of competitive athletes' body image pressures, only few studies have focused on adolescent sport participants' body image and the findings are inconclusive. Furthermore, the role of competitive goals in sports on adolescents' body size perception has not been studied. We examined the factors associated with adolescents' competitive goals in sports and body size perception, and the associations between adolescents' competitive goals in sports and body size perception. METHODS: The cross-sectional study consisted of 475 goal-oriented sports club participants and 936 reference youths (aged 14-16 years). The study questionnaire included multiple choice items on health behaviours, motives to exercise, competitive goals in sports and body size perception. The multinomial logistic regression analysis was used to investigate the associations. RESULTS: Adolescents with competitive goals in sports perceived their body size as about the right size more frequently than reference youths (68% vs 47%, p < 0.001 in girls; 74% vs 61%, p < 0.001 in boys). More than one-fourth of girls with competitive goals in sports perceived themselves as overweight, although only 7% of them were overweight. Adolescents with appearance/weight motives to exercise and poor perceived physical fitness had higher odds of perceived fatness. Additionally, BMI was positively associated with perceived fatness and negatively with perceived thinness. Having competitive goals in sports was not independently associated with perceived fatness or perceived thinness. CONCLUSIONS: Adolescents' BMI, appearance/weight motives to exercise, and perceived physical fitness were more strongly associated with body size perception than their competitive goals in sports. However, perceived fatness among girls with competitive goals in sports should be considered in organized sports.

Resting electrocardiogram and blood pressure in young athletes and nonathletes: A 4-year follow-up.

A follow-up data on electrocardiogram (ECG) and blood pressure (BP) changes in adolescent athletes are scarce. We compared ECG and BP between adolescent athletes and nonathletes in a 4-year follow-up. A total of 154 youth sports clubs (SC) in Finland and 100 secondary schools for comparison data participated in this observational follow-up study. Those who maintained or adopted SC participation are referred to as 'Always athletes' (n = 137), those who never participated in SC as 'Never athletes' (n = 108) and those who dropped out ofSC during the follow-up as 'Changers' (n = 116). The mean age of the participants was 15.5 (0.6) years in all study groups at baseline. Resting ECG including heart rate, PR interval, QRS duration, QRS axis, QRS amplitude, T axis and QT interval and BP were measured from all participants at baseline and after follow-up. 'Always athletes' had lower resting heart rate, more negative T-wave axis and higher QRS amplitude than 'Never athletes' at baseline and at 4 years (p < 0.05). 'Changers' had lower resting heart rate, more negative T-wave axis and higher QRS amplitude, systolic BP and pulse pressure than 'Never athletes' at baseline (p < 0.05). None of the observed differences at baseline, were visible at 4 years (p > 0.05) except the difference in T-wave axis (p = 0.028). The significant group × time interaction between 'Changers' and 'Never athletes' was found for QRS amplitude (p = 0.017). Adolescent athletes have several training-induced cardiovascular adaptations, which return towards the levels of nonathletes after cessation of regular training.

Resting Electrocardiogram and Blood Pressure in Young Endurance and Nonendurance Athletes and Nonathletes.

CONTEXT: Much information is available on electrocardiogram (ECG) and blood pressure (BP) changes in senior athletes. However, corresponding data on adolescent athletes are scarce. OBJECTIVE: To study the differences in resting ECG and BP values among adolescent endurance athletes, nonendurance athletes, and nonathletes. DESIGN: Cross-sectional study. SETTING: A total of 154 youth sports clubs in Finland and 100 secondary schools for comparison data. PATIENTS OR OTHER PARTICIPANTS: We recruited young athletes (n = 410) aged 14 to 16 years in 10 popular sport disciplines, including winter and summer as well as team and individual sports, and categorized them as endurance or nonendurance sports. Comparison data for age-matched, non-sports club participants (n = 164) were collected via secondary schools. MAIN OUTCOME MEASURE(S): Resting ECG, including heart rate, PR interval, QRS duration, QRS axis, QRS amplitude, T axis, and QT interval as well as systolic and diastolic BPs. RESULTS: No differences in any ECG variable of interest were found between the endurance and nonendurance athletes. The PR interval was longer in endurance athletes than in nonathletes (P = .05). The QRS amplitude (P = .03) was higher among nonendurance athletes than among nonathletes. Diastolic BP was lower among endurance (P = .002) and nonendurance (P = .02) athletes than among nonathletes. Endurance athletes (odds ratio [OR] = 2.85; 95% CI = 1.81, 4.50) and nonendurance athletes (OR = 2.19; 95% CI = 1.43, 3.35) were more likely to have sinus bradycardia than were nonathletes. Nonendurance athletes were more likely to have elevated systolic BP than were endurance athletes (OR = 1.70; 95% CI = 1.07, 2.72) and nonathletes (OR = 1.73; 95% CI = 1.04, 2.87). CONCLUSIONS: Young athletes had similar ECG and BP findings independent of their sports. Physiological adaptations including sinus bradycardia, higher QRS amplitude, and lower diastolic BP, which are commonly seen in adult athletes, were also present in adolescent athletes.

Menstrual dysfunction and body weight dissatisfaction among Finnish young athletes and non-athletes.

To determine the prevalence of menstrual dysfunction (MD; ie, oligomenorrhea or amenorrhea) and attitudes toward body weight among athletes and non-athletes, we studied a cohort of athletes and non-athletes, in adolescence (14-16 years) and subsequently in young adulthood (18-20 years). We further studied the differences between athletes reporting MD and eumenorrheic athletes at both time periods and identified physical and behavioral characteristics that might predict MD in young adulthood. Data were collected using questionnaires, accelerometers, and a pre-participation screening. In adolescence, the athletes reported current primary amenorrhea more often than the non-athletes (4.7% vs 0%, P = .03). In young adulthood, athletes reported MD more frequently than non-athletes (38.7% vs 5.6%, P < .001). Athletes had less desire than non-athletes to lose weight at both time points, and in adolescence, athletes were more satisfied with their weight. However, about one fifth of the athletes and about 40% of the non-athletes experienced body weight dissatisfaction at both time points. In adolescence, athletes reporting MD had lower BMI than eumenorrheic athletes. In young adulthood, athletes with MD were more physically active than eumenorrheic athletes. The only longitudinal predictor of MD in young adulthood was MD in adolescence. Our findings indicate that MD is relatively frequent among young Finnish athletes. However, athletes appear to have a smaller tendency to experience body weight dissatisfaction than their non-athletic peers. MD seems to track from adolescence to adulthood, suggesting that there is a need to focus on possible causes at the earliest feasible phase of an athlete's career.

Haemoglobin, iron status and lung function of adolescents participating in organised sports in the Finnish Health Promoting Sports Club Study.

OBJECTIVES: To compare laboratory test results and lung function of adolescent organised sports participants (SP) with non-participants (NP). METHODS: In this cross-sectional study, laboratory tests (haemoglobin, iron status), and flow-volume spirometry were performed on SP youths (199 boys, 203 girls) and their NP peers (62 boys, 114 girls) aged 14-17. RESULTS: Haemoglobin concentration <120/130 g/L was found in 5.8% of SP and 5.1% NP (OR 1.20, 95% CI 0.54 to 2.68). Ferritin concentration below 15 µg/L was found in 22.7% of both SP and NP girls. Among boys ferritin <30 µg/L was found in 26.5% of SP and 30.2% of NP (OR 0.76, 95% CI 0.40 to 1.47). Among SP iron supplement use was reported by 3.5% of girls and 1.5% of boys. In flow-volume spirometry with bronchodilation test, 7.0% of SP and 6.4% of NP had asthma-like findings (OR 1.17, 95% CI 0.54 to 2.54); those using asthma medication, that is, 9.8% of SP and 5.2% of NP were excluded from the analysis. CONCLUSIONS: Screening for iron deficiency is recommended for symptomatic persons and persons engaging in sports. Lung function testing is recommended for symptomatic persons and persons participating in sports in which asthma is more prevalent.

Musculoskeletal examination in young athletes and non-athletes: the Finnish Health Promoting Sports Club (FHPSC) study.

OBJECTIVES: To determine the inter-rater repeatability of a musculoskeletal examination and to compare findings between adolescent athletes and non-athletes in Finland. METHODS: In this cross-sectional study, a musculoskeletal examination assessing posture, mobility and movement control was carried out by a sports and exercise medicine physician on 399 athletes aged 14-17 years and 177 non-athletes. Within 2 weeks another sports and exercise medicine physician repeated the examination for 41 adolescents to test the inter-rater repeatability. RESULTS: In total, 10 of the 11 tests performed had at least moderate inter-rater reliability (κ ≥0.4 or percentage agreement >80%). Athletes more often than non-athletes had one shoulder protruded (8.0% vs 4.0%, OR 2.81, 95% CI 1.16 to 6.81). Forty-six per cent of athletes had good knee control in the two-legged vertical drop jump test compared with 32% of non-athletes (OR 1.99, 95% CI 1.29 to 3.06). Athletes had better core muscle control with 86.3% being able to remain in the correct plank position for 30 s compared with 68.6% of non-athletes (OR 2.70, 95% CI 1.67 to 4.36). In the deep squat test, good lumbar spine control was maintained only by 35.8% of athletes and 38.4% of non-athletes. CONCLUSION: A basic musculoskeletal examination is sufficiently reliable to be performed by trained physicians as a part of a periodic health evaluation. Shortfalls in mobility, posture and movement control are common in both athletes and non-athletes. These deficits could have been caused by sedentary behaviour, monotonous training, or both.

Exercise and gastrointestinal symptoms: running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners.

PURPOSE: Athletes frequently experience gastrointestinal (GI) symptoms during training and competition. Although the prevalence of exercise-induced GI symptoms is high, the mechanisms leading to GI distress during exercise are not fully understood. The aim of this study was to identify running-induced changes in intestinal permeability and markers of GI function and investigate their association with gastrointestinal symptoms. METHODS: We recruited 17 active runners who we allocated as either asymptomatic or symptomatic based on their history of experiencing GI symptoms during running. The participants took part in a running test where they were asked to run for 90 min at 80% of their best 10 km race speed. Intestinal permeability was measured at baseline and after the running test. Levels of serum intestinal fatty acid-binding protein (I-FABP), zonulin, bacterial lipopolysaccharide (LPS), and fecal calprotectin were also measured at baseline and after the running test. RESULTS: Running induced a significant increase in intestinal permeability and serum I-FABP concentration but there were no differences between asymptomatic and symptomatic runners. Serum LPS activity did not change from baseline following the running test but the symptomatic group exhibited higher LPS activity at baseline compared to the asymptomatic runners. CONCLUSIONS: Running for 90 min at a challenging pace causes small intestinal damage and increases intestinal permeability. However, these alterations in GI function do not appear to correlate with the development of GI symptoms during running.

Health promotion activities of sports clubs and coaches, and health and health behaviours in youth participating in sports clubs: the Health Promoting Sports Club study.

INTRODUCTION: Sports clubs form a potential setting for health promotion, but the research is limited. The aim of the Health Promoting Sports Club (HPSC) study was to elucidate the current health promotion activities of youth sports clubs and coaches, and to investigate the health behaviours and health status of youth participating in sports clubs compared to non-participants. METHODS AND ANALYSIS: The study design employs cross-sectional multilevel and multimethod research with aspirations to a prospective cohort study in the next phase. The setting-based variables at sports clubs and coaching levels, and health behaviour variables at the individual level, are investigated using surveys; and total levels of physical activity are assessed using objective accelerometer measurements. Health status variables will be measured by preparticipation screening. The health promotion activity of sports clubs (n=154) is evaluated by club officials (n=313) and coaches (n=281). Coaches and young athletes aged 14-16 (n=759) years evaluate the coaches' health promotion activity. The survey of the adolescents' health behaviours consist of two data sets-the first is on their health behaviours and the second is on musculoskeletal complaints and injuries. Data are collected via sports clubs (759 participants) and schools 1650 (665 participants and 983 non-participants). 591 (418 athletes and 173 non-athletes) youth, have already participated in preparticipation screening. Screening consists of detailed personal medical history, electrocardiography, flow-volume spirometry, basic laboratory analyses and health status screening, including posture, muscle balance, and static and dynamic postural control tests, conducted by sports and exercise medicine specialists. ETHICS AND DISSEMINATION: The HPSC study is carried out conforming with the declaration of Helsinki. Ethical approval was received from the Ethics Committee of Health Care District of Central Finland. The HPSC study is close-to-practice, which generates foundations for development work within youth sports clubs.

Localization of equilibrative nucleoside transporters in the rat brain.

Adenosine is a recognized inhibitory neuromodulator and neuroprotective agent in the central nervous system. It is produced both intra- and extracellularly and transported across the cell membrane. Nucleoside transporters thus have a major impact on the extracellular adenosine levels, and consequently adenosine signalling. We have raised and characterized polyclonal antibodies against both the equilibrative nucleoside transporters 1 and 2, and report for the first time their distribution in rat brain at the cellular level. Double staining studies were performed to assess the localization of the transporters in neural and glial cells. Both transporters were present in practically all neurons. Some astrocytes showed equilibrative nucleoside transporter 1 staining, while equilibrative nucleoside transporter 2 staining on astrocytes was observed only sporadically.

Actigraphic assessment of sleep in young adults with Asperger syndrome.

A high prevalence of subjective insomnia in adults with Asperger syndrome has been reported. In the present study the sleep quality of these patients was studied using wrist actigraphy. Nineteen adults with Asperger syndrome and frequent feelings of insomnia were compared with 10 controls devoid of neuropsychiatric disorders and subjective sleep problems during six consecutive nights. The patients had similar actigraphic sleep profile to the controls. The subjective low sleep quality in patients was not reflected in actigraphic assessment of sleep. This finding suggests that pervasive anxiety inherent in persons with Asperger syndrome predisposes them to insomnia complaints.

Adenosine A1 receptor-dependent G-protein activity in the rat brain during prolonged wakefulness.

Adenosine accumulates in the basal forebrain during prolonged wakefulness and induces sleep. There is abundant evidence showing that the sleep-inducing effects are mediated locally in the basal forebrain through the adenosine A1 receptor. In previous studies an increase in the mRNA expression but no apparent change in the ligand binding of the A1 receptors have been found. In the present study we used [(35)S]GTPgammaS autoradiography to assess regional A1 receptor dependent G-protein activity in rat brain during prolonged wakefulness and recovery sleep. We found that the G-protein activity was increased in the cortex but not in the basal forebrain during the first hours of sleep deprivation, suggesting different A1 receptor mediated responses to increasing adenosine concentrations in different brain areas.

The effect of age on prepro-orexin gene expression and contents of orexin A and B in the rat brain.

Orexin A and B (hypocretin 1 and 2) are hypothalamic peptides, which are synthesized in the lateral hypothalamus. Orexins participate in the regulation energy balance, food intake, vigilance and several endocrine and autonomic functions. The widespread projections of the orexin neurons suggest that they may have a role in coordination of different brain activities. The effects of ageing on the orexin system have not been studied previously. Prepro-orexin gene expression in the lateral hypothalamus, and the contents of orexin A and B peptides in the lateral hypothalamus and hypothalamus were measured in young, middle-aged and old (3, 12 and 24 months) rats. In the course of ageing, the expression of the prepro-orexin gene and the levels of orexin A and B decreased; the main decrease occurred by 12 months. Sleep deprivation for 6h increased slightly the expression of prepro-orexin gene in young rats. Deterioration of the orexin system may play a role in the phenomenon associated with aging, e.g. decreased consolidation of vigilance states, endocrine changes and dysfunctions of autonomic nervous system.

Nitrobenzylthioinosine (NBMPR) binding and nucleoside transporter ENT1 mRNA expression after prolonged wakefulness and recovery sleep in the cortex and basal forebrain of rat.

We have previously shown that extracellular adenosine levels increase locally in the basal forebrain (BF) during prolonged wakefulness, yet the cellular mechanisms of this local accumulation have remained unknown. The extracellular adenosine levels are strictly regulated by adenosine metabolism and its transport through cell membrane by the nucleoside transporters. As we previously showed that the key adenosine metabolizing enzymes were not affected by prolonged wakefulness, we now focussed on potential changes in the nucleoside transporters. In the present study, we measured the binding of nitrobenzylthioinosine (NBMPR), an ENT1 transporter inhibitor, and the ENT1 transporter mRNA after prolonged wakefulness and recovery sleep. Rats were sleep-deprived for 3 or 6 h using gentle handling. After 6 h one group was allowed to sleep for 2 h. NBMPR binding was determined from BF and cortex by incubating tissue extracts with [3H] NBMPR. The in situ hybridization was carried out on 20 microm cryosections using [35S]dATP-labelled oligonucleotide probe for ENT1 mRNA. The NBMPR binding was significantly decreased in the BF, but not in the cortex, after 6 h sleep deprivation when compared with the time-matched controls, suggesting a decline in adenosine transport. The expression of ENT1 mRNA did not change during prolonged wakefulness or recovery sleep in either cortex or the BF, although circadian variations were measured in both areas. We conclude that the regional decrease in adenosine transport could contribute to the gradual accumulation of extracellular adenosine in the basal forebrain during prolonged wakefulness.

Insomnia is a frequent finding in adults with Asperger syndrome.

BACKGROUND: Asperger syndrome (AS) is a neurodevelopmental disorder belonging to autism spectrum disorders with prevalence rate of 0,35% in school-age children. It has been most extensively studied in childhood while there is scarcity of reports concerning adulthood of AS subjects despite the lifelong nature of this syndrome. In children with Asperger syndrome the initiation and continuity of sleep is disturbed because of the neuropsychiatric deficits inherent of AS. It is probable that sleep difficulties are present in adulthood as well. Our hypothesis was that adults with AS suffer from difficulty in initiating and maintaining sleep and nonrestorative sleep (insomnia). METHODS: 20 AS without medication were compared with 10 healthy controls devoid of neuropsychiatric anamnesis. Clinical examination, blood test battery and head MRI excluded confounding somatic illnesses. Structured psychiatric interview for axis-I and axis-II disorders were given to both groups as well as Beck Depression Inventory and Wechsler adult intelligence scale, revised version.Sleep quality was assessed with sleep questionnaire, sleep diary during 6 consecutive days and description of possible sleep problems by the participants own words was requested. RESULTS: compared with controls and with normative values of good sleep, AS adults had frequent insomnia. In sleep questionnaire 90% (18/20), in sleep diary 75% (15/20) and in free description 85% (17/20) displayed insomnia. There was a substantial psychiatric comorbidity with only 4 AS subject devoid of other axis-I or axis-II disorders besides AS. Also these persons displayed insomnia. It can be noted that the distribution of psychiatric diagnoses in AS subjects was virtually similar to that found among patient with chronic insomnia. CONCLUSIONS: the neuropsychiatric deficits inherent of AS predispose both to insomnia and to anxiety and mood disorders. Therefore a careful assessment of sleep quality should be an integral part of the treatment plan in these individuals. Conversely, when assessing adults with chronic insomnia the possibility of autism spectrum disorders as one of the potential causes of this condition should be kept in mind.

Adenosine, energy metabolism, and sleep.

While the exact function of sleep remains unknown, it is evident that sleep was developed early in phylogenesis and represents an ancient and vital strategy for survival. Several pieces of evidence suggest that the function of sleep is associated with energy metabolism, saving of energy, and replenishment of energy stores. Prolonged wakefulness induces signs of energy depletion in the brain, while experimentally induced, local energy depletion induces increase in sleep, similarly as would a period of prolonged wakefulness. The key molecule in the induction of sleep appears to be adenosine, which induces sleep locally in the basal forebrain.

Local energy depletion in the basal forebrain increases sleep.

Sleep saves energy, but can brain energy depletion induce sleep? We used 2,4-dinitrophenol (DNP), a molecule which prevents the synthesis of ATP, to induce local energy depletion in the basal forebrain of rats. Three-hour DNP infusions induced elevations in extracellular concentrations of lactate, pyruvate and adenosine, as well as increases in non-REM sleep during the following night. Sleep was not affected when DNP was administered to adjacent brain areas, although the metabolic changes were similar. The amount and the timing of the increase in non-REM sleep, as well as in the concentrations of lactate, pyruvate and adenosine with 0.5-1.0 mM DNP infusion, were comparable to those induced by 3 h of sleep deprivation. Here we show that energy depletion in localized brain areas can generate sleep. The energy depletion model of sleep induction could be applied to in vitro research into the cellular mechanisms of prolonged wakefulness.

Adenosine kinase and 5'-nucleotidase activity after prolonged wakefulness in the cortex and the basal forebrain of rat.

The effect of prolonged wakefulness on adenosine kinase (AK), ecto-5'-nucleotidase and endo-5'-nucleotidase activity was assessed in the present study. Rats were sleep deprived for 3 or 6h, and one group was allowed to sleep 2h of recovery sleep after the 6h deprivation. The cortex and the basal forebrain were dissected, and frozen rapidly on dry ice. The enzyme activity of adenosine kinase was measured by monitoring the conversion of [2-3H]-adenosine into [3H]-adenosine monophosphate (AMP) and the ecto-5'-nucleotidase and endo-5'-nucleotidase activities by monitoring the conversion of [2-3H]-AMP into [3H]-adenosine. The enzyme activities did not change during deprivation or recovery sleep in either cortex or basal forebrain when compared to unhandled controls. Significant diurnal variation in enzyme activities was noted in both brain areas. In the basal forebrain adenosine kinase and both nucleotidases showed their lowest activity in the middle of the rest phase, 6h after lights on, suggesting a low level of adenosine metabolism, both production and degradation at this time point. In the cortex adenosine kinase had a diurnal activity pattern similar to the basal forebrain and the ecto-5'-nucleotidase activity was low already early in the rest phase, 3h after lights on, and remained low until the end part of the rest phase, 8h after lights on. Endo-5'-nucleotidase lacked diurnal variation. These activity patterns may be associated with the lower level of energy metabolism during sleep compared to wakefulness.

Adenosine and sleep.

Adenosine is directly linked to the energy metabolism of cells. In the central nervous system an increase in neuronal activity enhances energy consumption as well as extracellular adenosine concentrations. In most brain areas high extracellular adenosine concentrations, through A(1) adenosine receptors, decrease neuronal activity and thus the need for energy. Adenosine seems to act as a direct negative feed-back inhibitor of neuronal activity. Hypoxia and ischemia induce very high extracellular adenosine levels, which may limit further brain damage. In brain areas that regulate cortical vigilance, particularly in the basal forebrain, high extracellular adenosine concentrations, induced by prolonged wakefulness, decrease the activity of presumably cholinergic cells and via this mechanism promote sleep. Our hypothesis is that in the cholinergic basal forebrain prolonged wakefulness induces local energy depletion that generates increases in extracellular adenosine concentrations in this area. In addition to the immediate effects, high extracellular adenosine concentrations also induce intracellular changes in signal transduction and transcription, e.g. increase in A(1) receptor expression and NF-kappaB binding activity. These changes may at least partially mediate the long term effects of prolonged wakefulness. Adenosine may also be a common mediator of the effects of several other sleep-inducing factors.