The influence of clinic care on perceptions and knowledge of non-communicable diseases and physical activity from a low-resourced community: a mixed-method study.

BACKGROUND: Health promotion for the management of risk factors for non-communicable diseases (NCDs) is an integral part of standard care in South Africa. Most persons presenting with NCDs utilise public primary health care centres for disease management. This mixed-methods study aimed at expanding current understanding of the the influence of standard clinic care (usual care) on perceptions and knowledge of risk factors for NCDs and physical activity (PA) among persons from a low-resourced community. Qualitatively the perceptions of women from a low-resourced community about risk factors for NCDs and PA were explored throughout 24-weeks of standard clinic care. Parallel quantitative data was collected to describe changes in risk factors for NCDs and trends in self-reported knowledge about risk factors of NCDs and PA. METHOD: A convergent-parallel mixed-methods research design was used. The study was carried out in a public primary health care setting, in the North West Province, South Africa. From a convenience sample of 100 participants, 77 African women aged between 34 and 79 years were recruited for the study. Data were collected at three time-points including baseline, 12 weeks, and 24 weeks of a standard clinic care health-promotion programme. The qualitative data was collected during focus group discussions, and the quantitative data included questionnaires on knowledge of physical activity and risk factors for NCDs as well as anthropometric and biological measurements. Qualitative and quantitative data were analysed independently for each phase and then consolidated for interpretation. All data was collected in the same setting. RESULTS: Participants' initial understanding and perceptions of NCD risk factors were poor. Qualitative findings showed that participants knew little about the specific physical activity they could engage in and the role of PA in NCD management. Participants preferred low-intensity activities. Heart-disease knowledge improved significantly at 12 weeks intervention compared to baseline MD = -3.655, p < 0.001. There were improvements in PA knowledge at 12 weeks from baseline MD = -0.625 p = 0.02. There were significant weight (MD = 1.420, p = 0.002) and waist circumference reductions (MD = 0.621, p = 0.02) from baseline to 24 weeks. CONCLUSION: Standard clinic care improved knowledge of physical activity and risk factors for NCDs, but perceptions of risk factors for NCDs and PA were unchanged. This study offers insight into the perceptions held by women from a low-resource setting and how future interventions to manage and prevent NCDs should be structured. TRIAL REGISTRATION: PACTR201609001771813 .

Quality of life, physical activity and cardiorespiratory fitness in black African women: B-Healthy project.

PURPOSE: To study the associations between physical activity (PA), cardiorespiratory fitness (CRF), and health-related quality of life (HRQoL) in black African women from a low socioeconomic community in South Africa. METHODS: Black African women (n = 146) aged 35-75 years from a low socioeconomic community in South Africa participated in this study. We measured PA levels via ActiHeart® accelerometers, and CRF by measuring peak oxygen consumption (V̇O2 peak). HRQoL was assessed once with the SF-8 Health Survey (SF-8). Participants were classified into groups based on age, moderate to vigorous PA (MVPA), and V̇O2 peak. Logistic regressions were used to compare the odds of having total HRQoL component scores above reported norms across PA and fitness groups. Two multiple linear regression models were developed using physical component summary (PCS) and mental component summary (MCS) as response variables respectively. RESULTS: V̇O2 peak and MVPA varied considerably across the sample and declined with increasing age. Participants in higher quartiles of MVPA and CRF showed trends to higher PCS scores. For CRF these trends were statistically significant, and persisted after adjustment for age and other possible confounders (p = 0.036). PCS was significantly associated with age, relative V̇O2 peak, and income (all p < 0.05), while MCS was associated with income (p = 0.028). CONCLUSIONS: CRF is the most significant predictor, together with age and income, on the PCS of the HRQoL among black African women. We recommend that when seeking improvements in HRQoL, interventions should focus on improving CRF, particularly V̇O2 peak.

Early postnatal GABAA receptor modulation reverses deficits in neuronal maturation in a conditional neurodevelopmental mouse model of DISC1.

Exploring drug targets based on disease-associated molecular mechanisms during development is crucial for the generation of novel prevention and treatment strategies for neurodevelopmental psychiatric conditions. We report that prefrontal cortex (PFC)-specific postnatal knockdown of DISC1 via in utero electroporation combined with an inducible knockdown expression system drives deficits in synaptic GABAA function and dendritic development in pyramidal neurons, as well as abnormalities in sensorimotor gating, albeit without profound memory deficits. We show for the first time that DISC1 is specifically involved in regulating cell surface expression of α2 subunit-containing GABAA receptors in immature developing neurons, but not after full maturation. Notably, pharmacological intervention with α2/3 subtype-selective GABAA receptor positive allosteric modulators during the early postnatal period ameliorates dendritic deficits and behavioral abnormalities induced by knockdown of DISC1. These findings highlight a critical role of DISC1-mediated disruption of postnatal GABA signaling in aberrant PFC maturation and function.

Effect of continuous aerobic vs. interval training on selected anthropometrical, physiological and functional parameters of adults with Down syndrome.

BACKGROUND: A large percentage of adults with Down syndrome (DS) are overweight and have extremely low aerobic capacities compared with the general population and persons with intellectual disability without DS. Previous aerobic training intervention studies showed limited potential to significantly ameliorate anthropometrical and cardiovascular variables. The primary purpose of this study was to determine the effect of continuous aerobic training (CAT) vs. interval training (IT) on selected anthropometrical, health, physical and functional parameters of adults with DS. METHODS: Forty-two adults with DS (25 men and 17 women) and a mean age of 33.8 (±8.6) years were randomly allocated to one of three groups (IT, CAT and control). Training was performed for 12 weeks. The IT group performed 10-30 s all out sprints with 90 s (1:3 work-rest ratio) of low cadence, low intensity cycling or walking. The CAT group performed continuous cycling and walking at an intensity of 70-80% of VO2 peak. Heart rate monitors were used for monitoring training intensities. After 6 weeks of training, the intensity of the CAT was increased to 85% of VO2 peak, whilst the intensity of the IT group remained 'all out'. An increase of 5 min in duration was implemented after 6 weeks for both training groups. To evaluate pre-post differences between groups, a repeated analysis of covariance with post hoc Bonferroni test was performed RESULTS: After 12 weeks of training, body weight and body mass index decreased significantly more in the IT group compared with control and CAT (P < 0.05). Participants in the IT group decreased their body weight from 71.4 ± 8 to 69.4 ± 8 kg and their body mass index from 29.3 ± 4 to 28.5 ± 4 kg/m2 . Significant ameliorations for functional parameters and leg strength were shown for CAT compared with control (P < 0.05). Participants in the CAT group improved their performance in the 6 minute walk distance (499 ± 78 to 563 ± 75 m), 8-ft up-and-go (5.9 ± 1.2 to 4.8 ± 0.9) and leg strength (13.1 ± 2 to 15.2 ± 2). VO2 peak and time to exhaustion significantly improved in both the IT and CAT group compared with control (P < 0.01). Moreover, a significant improvement for relative VO2 peak was also determined for IT compared with CAT (P < 0.05). Participants in the IT group increased their VO2 peak from 32 ± 8 to 37 ± 8 mL/min/kg. Submaximal heart rate and VO2 values improved significantly within both exercise groups (P < 0.05). CONCLUSION: Interval training and CAT can both be pursued by adults with DS to positively impact on various parameters of anthropometry, fitness and functional ability, with IT more appropriate for improving body weight and aerobic capacity.

Test-retest reliability and minimal detectable change scores of twelve functional fitness tests in adults with Down syndrome.

AIM: The purpose of the study was to explore the test-retest reliability and minimal detectable change of selected functional fitness test items in adults with Down syndrome. METHODS: Forty-three adults with Down syndrome (24 men and 19 women) aged 18-50 years completed a battery of tests twice in a two-week period. The battery of tests consisted of two balance items, two flexibility items, five muscular strength and endurance items, two aerobic items, and one functional task. All items were considered valid and reliable tests in a general elderly or intellectually disabled population. The test-retest relative reliability for all repeated tests was assessed with intraclass correlation coefficient performing one-way analysis of variance. The test-retest absolute variability was measured by using the standard error of measurement (SEM) to calculate the minimal detectable change at the 90% confidence interval (MDC90). Reliability data was visualised with a Bland-Altman plot. RESULTS: All tests showed excellent intraclass correlation coefficients (ICC's>0.9). All SEM values demonstrated acceptable measurement precision (SEM

Relationship of adiposity and cardiorespiratory fitness with resting blood pressure of South African adolescents: the PAHL Study.

Obesity and low level of cardiorespiratory fitness are associated with high blood pressure in both adolescents and adults. The objective of this study was to assess the relationship of adiposity and cardiorespiratory fitness with resting blood pressure in 14-year-old male and female adolescents. Cross-sectional data on 310 adolescents (31.8% boys) from six high schools, who were participating in the on-going Physical Activity and Health Longitudinal Study, were collected. Height, weight, body mass index (BMI), percentage of body fat, waist circumference, waist-to-height ratio, predicted and resting systolic (SBP) and diastolic blood pressure (DBP) were assessed according to standard procedures. The prevalence of elevated SBP and DBP were 4.9% and 6.5%, respectively. The highest prevalence of elevated blood pressure (SBP=10% and DBP=15%) were measured in overweight adolescents, who also performed poorly for predicted VO(2max)(M=26.66 ml kg(-1 )min(-1)±6.44) compared with underweight and normal-weight adolescents. Multiple regression showed that BMI was positively associated with SBP (ß=0.77, P=0.005) and VO(2max) was negatively associated with DBP (ß=-0.43, P=0.001). Overweight adolescents presented with a relatively high prevalence of elevated blood pressure and poor health-related fitness. Fatness and poor cardiorespiratory fitness were positively associated with elevated SBP and DBP, respectively. In view of the health implications of these findings, strategic interventions are needed to promote obesity-reduction programmes and physical activities in adolescents.

Antidepressant effects of sleep deprivation require astrocyte-dependent adenosine mediated signaling.

Major depressive disorder is a debilitating condition with a lifetime risk of ten percent. Most treatments take several weeks to achieve clinical efficacy, limiting the ability to bring instant relief needed in psychiatric emergencies. One intervention that rapidly alleviates depressive symptoms is sleep deprivation; however, its mechanism of action is unknown. Astrocytes regulate responses to sleep deprivation, raising the possibility that glial signaling mediates antidepressive-like actions of sleep deprivation. Here, we found that astrocytic signaling to adenosine (A1) receptors was required for the robust reduction of depressive-like behaviors following 12 hours of sleep deprivation. As sleep deprivation activates synaptic A1 receptors, we mimicked the effect of sleep deprivation on depression phenotypes by administration of the A1 agonist CCPA. These results provide the first mechanistic insight into how sleep deprivation impacts mood, and provide a novel pathway for rapid antidepressant development by modulation of glial signaling in the brain.

Evidence for sustained elevation of IL-6 in the CNS as a key contributor of depressive-like phenotypes.

There is compelling clinical literature implicating a role for cytokines in the pathophysiology of major depressive disorder (MDD). Interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) are pleiotropic inflammatory cytokines that have been reported to be elevated in patients with MDD. The present studies were undertaken to investigate the relationship between IL-6 and IL-1ß in animal models of depressive-like behavior. Analysis of brain tissue homogenates in the cortex of rats subjected to chronic stress paradigms revealed elevated levels of IL-6 protein in the absence of elevations in IL-1ß. Central administration of recombinant mouse IL-6 produced depressive-like phenotypes in mice, which were not accompanied by IL-1ß-induced increases in the brain tissue or IL-1ß-related sickness behavior typical of a general central nervous system inflammatory response. Systemic administration of fluoxetine in the presence of centrally administered IL-6 failed to produce the expected antidepressant-like response in mice relative to sham-infused controls. Further, administration of fluoxetine to mice with endogenous overexpression of brain IL-6 (MRL/MpJ-Fas(LPR/LPR) (LPR mice)) failed to produce the expected antidepressant-like effect relative to fluoxetine-treated control mice (MRL/MpJ(+/+)). Interestingly, blockade of IL-6 trans-signaling by coadministration of a gp130/Fc monomer or an anti-mouse IL-6 antibody with IL-6 prevented the IL-6-induced increases in immobility time as well as attenuated IL-6-induced increases of protein in the cortex. Taken together, these data indicate that elevations in IL-6 may have a pathophysiological role underlying depression and more specifically resistance to current classes of antidepressant medications and suggest that modulation of the IL-6 signaling pathway may have therapeutic potential for treatment-resistant depression.

Estrous cycle variations in GABA(A) receptor phosphorylation enable rapid modulation by anabolic androgenic steroids in the medial preoptic area.

Anabolic androgenic steroids (AAS), synthetic testosterone derivatives that are used for ergogenic purposes, alter neurotransmission and behaviors mediated by GABA(A) receptors. Some of these effects may reflect direct and rapid action of these synthetic steroids at the receptor. The ability of other natural allosteric steroid modulators to alter GABA(A) receptor-mediated currents is dependent upon the phosphorylation state of the receptor complex. Here we show that phosphorylation of the GABA(A) receptor complex immunoprecipitated by ß(2)/ß(3) subunit-specific antibodies from the medial preoptic area (mPOA) of the mouse varies across the estrous cycle; with levels being significantly lower in estrus. Acute exposure to the AAS, 17α-methyltestosterone (17α-MeT), had no effect on the amplitude or kinetics of inhibitory postsynaptic currents in the mPOA of estrous mice when phosphorylation was low, but increased the amplitude of these currents from mice in diestrus, when it was high. Inclusion of the protein kinase C (PKC) inhibitor, calphostin, in the recording pipette eliminated the ability of 17α-MeT to enhance currents from diestrous animals, suggesting that PKC-receptor phosphorylation is critical for the allosteric modulation elicited by AAS during this phase. In addition, a single injection of 17α-MeT was found to impair an mPOA-mediated behavior (nest building) in diestrus, but not in estrus. PKC is known to target specific serine residues in the ß(3) subunit of the GABA(A) receptor. Although phosphorylation of these ß(3) serine residues showed a similar profile across the cycle, as did phosphoserine in mPOA lysates immunoprecipitated with ß2/ß3 antibody (lower in estrus than in diestrus or proestrus), the differences were not significant. These data suggest that the phosphorylation state of the receptor complex regulates both the ability of AAS to modulate receptor function in the mPOA and the expression of a simple mPOA-dependent behavior through a PKC-dependent mechanism that involves the ß(3) subunit and other sites within the GABA(A) receptor complex.

The psychiatric disease risk factors DISC1 and TNIK interact to regulate synapse composition and function.

Disrupted in schizophrenia 1 (DISC1), a genetic risk factor for multiple serious psychiatric diseases including schizophrenia, bipolar disorder and autism, is a key regulator of multiple neuronal functions linked to both normal development and disease processes. As these diseases are thought to share a common deficit in synaptic function and architecture, we have analyzed the role of DISC1 using an approach that focuses on understanding the protein-protein interactions of DISC1 specifically at synapses. We identify the Traf2 and Nck-interacting kinase (TNIK), an emerging risk factor itself for disease, as a key synaptic partner for DISC1, and provide evidence that the DISC1-TNIK interaction regulates synaptic composition and activity by stabilizing the levels of key postsynaptic density proteins. Understanding the novel DISC1-TNIK interaction is likely to provide insights into the etiology and underlying synaptic deficits found in major psychiatric diseases.

Responses to a conjugate pneumococcal vaccine in preterm infants immunized at 2, 3, and 4 months of age.

Preterm infants are at an increased risk of invasive pneumococcal disease infection and, additionally, have a diminished response to Haemophilus influenzae type b (Hib) conjugate vaccines. There are little data examining the response of preterm infants to a seven-valent pneumococcal conjugate vaccine (PCV7). We examined the responses of preterm infants immunized at 2, 3, and 4 months of age to PCV7. A total of 133 preterm and 54 term infants were immunized with PCV7 and the Neisseria meningitidis group C (MCC), diphtheria, tetanus, pertussis, polio, and Hib vaccines. Pneumococcal serotype-specific IgG was measured by enzyme-linked immunosorbent assay (ELISA) pre- and postimmunization and at 12 months or following a booster of PCV7. Term and preterm responses were compared using linear and logistic regression analyses. Term infants had higher preimmunization geometric mean concentrations (GMCs) for all serotypes. Preterm infants had lower postimmunization GMCs for serotype 23F. Gestational age affected postimmunization GMCs for serotypes 4, 6B, and 23F. Preterm infants were as likely to have levels of ≥0.35 µg/ml as term infants for all serotypes except 23F. The proportions of infants with titers of ≥0.35 µg/ml for all 7 serotypes were comparable between groups. A total of 28 of 29 term infants who received a booster had levels of ≥0.35 µg/ml for all serotypes. One infant had undetectable levels for serotype 6B. Of the 32 preterm infants boosted, 9 had levels of <0.35 µg/ml for 1 serotype, and 1 had levels of <0.35 µg/ml for 2 serotypes. In nonboosted infants, GMCs for all serotypes except 6B had fallen by 12 months of age. These results support the need for a booster dose in the second year of life.

Immunogenicity of a heptavalent conjugate pneumococcal vaccine administered concurrently with a combination diphtheria, tetanus, five-component acellular pertussis, inactivated polio, and Haemophilus influenzae type B vaccine and a meningococcal group C conjugate vaccine at 2, 3, and 4 months of age.

The immunogenicities of conjugate pneumococcal vaccines have been demonstrated when they are administered at 2, 3, and 4 months of age. There is a paucity of data on the immunogenicity of this vaccine when it is administered concurrently with other vaccines in the primary immunization schedule of the United Kingdom. We immunized 55 term infants at 2, 3, and 4 months of age with the seven-valent pneumococcal conjugate vaccine (PCV7), the meningococcal group C conjugate (MCC) vaccine, and the diphtheria, tetanus, five-component acellular pertussis, inactivated polio, and Haemophilus influenzae type b (DTaP(5)/IPV/Hib-TT) vaccine. The immune responses to the H. influenzae type b (Hib), MCC, and tetanus vaccines were measured at 2, 5, and 12 months of age; and the immune responses to PCV7 were measured at 2 and 5 months and then either at 12 months or following a 4th dose of PCV7. There were increases in the geometric mean concentrations (GMCs) of all antigens postimmunization. Greater than or equal to 90% of the infants achieved putatively protective levels postimmunization for all vaccine antigens except pneumococcal serotype 6B and Hib. The GMCs of the PCV7 serotypes increased following a 4th dose, although one infant had not reached putative levels of protection against serotype 6B. In conclusion, when infants were vaccinated according to the schedule described above, they had lower postprimary immunization responses to Hib, meningococcus group C capsular polysaccharide, and pneumococcal serotype 6B than the responses demonstrated by use of the other schedules. Despite this finding, there was a good response following a 4th dose of PCV7.

Changes in coronary heart disease risk profile of adults with intellectual disabilities following a physical activity intervention.

BACKGROUND: Regular physical activity is one of the modifiable risk factors for coronary heart disease (CHD). With an increasing age profile and similar patterns of morbidity to the general population, persons with intellectual disabilities (ID) and their caregivers would benefit from data that indicate CHD risk factors. Knowledge of the CHD risk factors and the changes a physical activity intervention may have on theses risk factors will facilitate future intervention programmes. METHODS: A cohort of 100 men and women between the ages of 21 and 73 years with ID living in a community group home in the North-West Province of South Africa was recruited. A CHD risk profile was compiled by means of a questionnaire and physical assessment that included resting blood pressure, body mass index, non-fasting glucose and cholesterol and cardiorespiratory fitness. A 12-week physical activity intervention was then conducted 3 days/week after which the baseline measurements were repeated. RESULTS: The results indicated that 85% of the participants were inactive, while 67% were overweight and obese. Hypertension (6.1%) and smoking (6.1%) were relatively low in this population with ID. Glucose concentrations above the recommended cut-off values were observed in 28% of the participants. Total cholesterol concentrations above normal were measured in 23% of the participants. The physical activity intervention reduced inactivity to 50% and resulted in a significant increase in cardiorespiratory fitness and a decrease in percentage body fat in both men and women. CONCLUSION: Inactivity is a major risk factor in this population with ID living in a community group setting. The implementation of the physical activity intervention significantly reduced the risk factors for CHD.

Towards safer neonatal transfer: the importance of critical incident review.

BACKGROUND: Critical incidents are common during the inter-hospital transfer of sick patients, and infants are an especially vulnerable group. AIMS: To examine the effect of critical incident review on the number of adverse events during inter-hospital transfer of sick infants. METHODS: Critical incidents over an eight year period are reported from a single neonatal transfer service before and after major service changes were made. The changes were instigated as part of ongoing critical incident reviews. RESULTS: Changes made as a result of critical incident review significantly reduced the number of incidents contributed to by poor preparation, transport equipment or clinical problems, ambulance delays, and ambulance equipment failure. CONCLUSIONS: The continuous process of critical incident reporting and review can reduce the number of adverse events during the transfer of critically ill infants.

Cyclic AMP-dependent protein kinase phosphorylation facilitates GABA(B) receptor-effector coupling.

GABA (gamma-aminobutyric acid)(B) receptors are heterodimeric G protein-coupled receptors that mediate slow synaptic inhibition in the central nervous system. Here we show that the functional coupling of GABA(B)R1/GABA(B)R2 receptors to inwardly rectifying K(+) channels rapidly desensitizes. This effect is alleviated after direct phosphorylation of a single serine residue (Ser892) in the cytoplasmic tail of GABA(B)R2 by cyclic AMP (cAMP)-dependent protein kinase (PKA). Basal phosphorylation of this residue is evident in rat brain membranes and in cultured neurons. Phosphorylation of Ser892 is modulated positively by pathways that elevate cAMP concentration, such as those involving forskolin and beta-adrenergic receptors. GABA(B) receptor agonists reduce receptor phosphorylation, which is consistent with PKA functioning in the control of GABA(B)-activated currents. Mechanistically, phosphorylation of Ser892 specifically enhances the membrane stability of GABA(B) receptors. We conclude that signaling pathways that activate PKA may have profound effects on GABA(B) receptor-mediated synaptic inhibition. These results also challenge the accepted view that phosphorylation is a universal negative modulator of G protein-coupled receptors.

Comparison of two intracranial self-stimulation (ICSS) paradigms in C57BL/6 mice: head-dipping and place-learning.

A variety of intracranial self-stimulation (ICSS) paradigms have been utilized for investigations of reward. Among them, nose-poking and spatial-preference paradigms are known to be relatively more resistant to the effects of drug-induced motor-deficits in rat studies, although these two ICSS paradigms have not been directly compared in previous studies. In the present study, head-dipping and place-learning (forms of nose-poking and spatial-preference tasks, respectively) paradigms with lateral hypothalamus stimulation were systematically analyzed using C57BL/6 mice in the presence and absence of two motor-deficit-inducing drugs: tolperisone and harmaline. Rapid acquisition and rapid extinction patterns of ICSS responding were observed in the head-dipping and place-learning paradigms. In contrast to these pre-drug similarities in responding, dramatic differences were noted after drug administration. Tolperisone significantly reduced head-dipping but not place-learning ICSS responding. Similarly, reduction of ICSS responding after harmaline was more pronounced in the head-dipping task. Therefore, the place-learning paradigm may be superior for the assessment of reward values under motor-deficit-inducing conditions in C57BL/6 mice. The relative benefits and disadvantages of both ICSS paradigms are discussed. Combinations of complementary ICSS paradigms using mice may be useful for further investigations of the molecular bases of reward.

3-acetylpyridine reduces tongue protrusion force but does not abolish lick rhythm in the rat.

Data from other laboratories suggest that neurons in the inferior olivary nucleus (IO) may play a role in the modulation of rhythmic tongue movements in rats. Because of its known harmful effects on neurons of the IO, it was suspected that administration of the neurotoxin 3-acetylpyridine (3AP) would affect subsequent tongue dynamics during rat licking. In the present study, the task of licking water from a force-transducing disk was investigated in water-restricted rats that received systemic administration of 3AP (12.5, 25, and 50 mg/kg). After recovery from the acute toxic effects of 3AP, tongue dynamics were assessed by measuring lick force, lick rhythm, variability of timing within bursts of licking, and number of licks per 2-min session. At 50 mg/kg, 3AP resulted in: (1) reduced lick force; (2) reduced number of licks; and (3) increased variance in the timing within bursts. Lick rhythm was not significantly affected by any dose of 3AP. All 3AP treatment groups and the vehicle control group displayed slowing of lick rhythm after harmaline challenge. Compared to vehicle controls, rats receiving lower and mid-range doses of 3AP displayed indistinguishable lick behaviors, with one exception--when the lick task was made incrementally more difficult by extending the distance required to make contact with the lick-disk, rats that had received 25 mg/kg 3AP persevered at the task more than all other rats. The various changes in lick dynamics may be due to the detrimental effects of 3AP at the IO, and possibly at the hypoglossal nucleus and other sites.

Constitutive tyrosine phosphorylation of the GABA(A) receptor gamma 2 subunit in rat brain.

GABA(A) receptors are the major sites of fast synaptic inhibition in the brain, where they are predominantly composed of alpha, beta and gamma2 subunits. A role for direct tyrosine phosphorylation of residues 365 and 367 (Y365/367) within the intracellular domain of the gamma2 subunit has been suggested to be important in modulating GABA(A) receptor function, based on the study of recombinant receptors. To address the relevance of these observations for neuronal GABA(A) receptors we have studied the phosphorylation of the gamma2 subunit in the brain. In adult rat brain the gamma2 subunit is phosphorylated on tyrosine residues, including Y365/367 as defined using a phosphospecific antisera. In cultured cortical neurones, phosphorylation of Y365/367 is highly regulated and was only evident upon inhibition of tyrosine phosphatases. We also establish that the tyrosine kinase Src is capable of specifically interacting with the intracellular domains of receptor beta and gamma2 subunits. This may specifically localise tyrosine kinase activity to GABA(A) receptors, facilitating rapid receptor tyrosine phosphorylation upon kinase activation. Together our results suggests that tyrosine phosphorylation of the gamma2 subunit, possibly by closely associated Src, may be a dynamic mechanism for regulating GABA(A) receptor function in the brain.