A Randomized Trial of Maternal Docosahexaenoic Acid Supplementation to Reduce Inflammation in Extremely Preterm Infants

Maternal supplementation with 1000 mg/day docosahexaenoic acid (DHA) provides third trimester DHA accretion levels in breast milk for the preterm infant. We hypothesized that DHA supplementation to mothers providing breastmilk for extremely preterm infants would result in decreased inflammatory markers, in the infant. Mother/infant dyads (n = 27) were enrolled at birth and mothers were assigned to receive 200 or 1000 mg/day of DHA. Milk and plasma samples were analyzed for fatty acids and inflammatory markers. Decreases in inflammation were observed in both maternal and infant plasma and correlated with red blood cell (RBC) DHA levels. The fact that maternal DHA supplementation decreases infant markers of inflammation implies that DHA, delivered through breastmilk, has the potential to decrease inflammation in the infant.

Role of interleukin-10 (IL-10) in regulation of GABAergic transmission and acute response to ethanol

Mounting evidence indicates that ethanol (EtOH) exposure activates neuroimmune signaling. Alterations in pro-inflammatory cytokines after acute and chronic EtOH exposure have been heavily investigated. In contrast, little is known about the regulation of neurotransmission and/or modulation by anti-inflammatory cytokines in the brain after an acute EtOH exposure. Recent evidence suggests that interleukin-10 (IL-10), an anti-inflammatory cytokine, is upregulated during withdrawal from chronic EtOH exposure. In the present study, we show that IL-10 is increased early (1 h) after a single intoxicating dose of EtOH (5 g/kg, intragastric) in Sprague Dawley rats. We also show that IL-10 rapidly regulates GABAergic transmission in dentate gyrus neurons. In brain slice recordings, IL-10 application dose-dependently decreases miniature inhibitory postsynaptic current (mIPSC) area and frequency, and decreases the magnitude of the picrotoxin sensitive tonic current (Itonic), indicating both pre- and postsynaptic mechanisms. A PI3K inhibitor LY294002 (but not the negative control LY303511) ablated the inhibitory effects of IL-10 on mIPSC area and Itonic, but not on mIPSC frequency, indicating the involvement of PI3K in postsynaptic effects of IL-10 on GABAergic transmission. Lastly, we also identify a novel neurobehavioral regulation of EtOH sensitivity by IL-10, whereby IL-10 attenuates acute EtOH-induced hypnosis. These results suggest that EtOH causes an early release of IL-10 in the brain, which may contribute to neuronal hyperexcitability as well as disturbed sleep seen after binge exposure to EtOH. These results also identify IL-10 signaling as a potential therapeutic target in alcohol-use disorders and other CNS disorders where GABAergic transmission is altered.

Differential effects of systemic ethanol administration on protein kinase cepsilon, gamma, and beta isoform expression, membrane translocation, and target phosphorylation: reversal by chronic ethanol exposure

Systemic ethanol administration alters protein kinase C (PKC) activity in brain, but the effects of ethanol on the expression and translocation of specific isoforms are unknown. Rats were administered ethanol (2 g/kg i.p.) or saline and PKC levels were measured in the cytosolic and membrane fractions by Western blot analysis. PKCepsilon expression was increased in the cytosol and decreased in the membrane (P2) fraction of cerebral cortex at 10 min. At 60 min, expression of PKCepsilon in the P2 fraction was increased by 42.2 +/- 12%, but cytosolic levels were unchanged. In contrast, PKCgamma in the P2 fraction was decreased 32.7 +/- 7% at 60 min but not at 10 min post-ethanol administration. PKCgamma levels in the cytosol were reduced at 10 min post-ethanol administration and unchanged at 60 min. PKCbeta expression was increased 36 +/- 10 and 144 +/- 52% in the P2 fraction both at 10 and 60 min post-ethanol administration, whereas cytosolic levels were unchanged. Serine phosphorylation of GABA(A) receptor beta-chain was reduced, and phosphorylation of N-methyl-d-aspartate receptor NR1 subunit was increased 60 min following ethanol administration. There was no effect of acute ethanol administration on PKC isoform levels in the hippocampus. Ethanol challenge did not alter PKC isoform expression in the P2 fraction of cerebral cortex following chronic ethanol administration. These findings suggest that acute ethanol administration alters PKC synthesis and translocation in an isoform and brain region specific manner that leads to alterations in serine phosphorylation of receptors. Furthermore, chronic ethanol administration prevents ethanol-induced alterations in PKC expression in the P2 fraction, where PKC interacts with ethanol-responsive ion channels.

Basis of the gabamimetic profile of ethanol

This article summarizes the proceedings of a symposium held at the 2005 Research Society on Alcoholism meeting. The initial presentation by Dr. Wallner provided evidence that selected GABA(A) receptors containing the delta subunit display sensitivity to low intoxicating ethanol concentrations and this sensitivity is further increased by a mutation in the cerebellar alpha6 subunit, found in alcohol-hypersensitive rats. Dr. Mameli reported that ethanol affects gamma-aminobutyric acid (GABA) function by affecting neural circuits that influence GABA release. Dr. Parsons presented data from electrophysiological and microdialysis investigations that ethanol is capable of releasing GABA from presynaptic terminals. Dr. Morrow demonstrated that systemic ethanol increases neuroactive steroids in brain, the absence of which alters various functional responses to ethanol. Dr. Criswell presented evidence that the ability of ethanol to increase GABA was apparent in some, but not all, brain regions indicative of regional specificity. Further, Dr. Criswell demonstrated that neurosteroids alone and when synthesized locally by ethanol act postsynaptically to enhance the effect of GABA released by ethanol in a region specific manner. Collectively, this series of reports support the GABAmimetic profile of acutely administered ethanol being dependent on several specific mechanisms distinct from a direct effect on the major synaptic isoforms of GABA(A) receptors.

Perinatal allopregnanolone influences prefrontal cortex structure, connectivity and behavior in adult rats

Cortical neurosteroid levels vary dramatically across development; during the second week of life elevated levels of allopregnanolone are associated with decreased GABA(A) receptor function. Since GABA(A) receptor modulation plays a role in proliferative regulation in developing neocortex, it is possible that endogenous neurosteroids such as allopregnanolone, acting through GABA(A) receptors, modulate cortical development. We augmented normally low levels with exogenous administration of allopregnanolone (10 mg/kg) during the first week of rodent life. The localization of parvalbumin-labeled cells was markedly altered; the ratio of cell number in the deep (layers V-VI) vs. superficial (layers I-III) layers of adult prefrontal cortex increased two-fold in rats administered allopregnanolone on postnatal day 1 or 5. The mechanism underlying these anatomical changes likely involves GABA(A) receptors because similar changes in interneuron placement were observed after neonatal benzodiazepine administration. Measures of mature cortical function were also altered after neonatal neurosteroid administration, including [(3)H]MK-801 binding, prepulse inhibition and amphetamine-induced locomotor activity. Moreover, neonatal allopregnanolone administration increases the number of parvalbumin-expressing neurons in medial dorsal nucleus of the thalamus while the total neuron number is decreased. These findings suggest that connectivity between the medial dorsal nucleus of the thalamus and prefrontal cortex is likely altered by neonatal neurosteroid administration and may result in a disinhibited frontal cortex. Disinhibition in the prefrontal cortex is associated with behavioral changes relevant to human psychosis and developmental disorders. If neurosteroids play a role in normal development of prefrontal/medial dorsal patency as suggested by these studies, then alterations in neurosteroid levels may contribute to abnormal neurodevelopment.

A gain-of-function mutation in the GABAA receptor produces synaptic and behavioral abnormalities in the mouse

In mammalian species, inhibition in the brain is mediated predominantly by the activation of GABAA receptors. We report here changes in inhibitory synaptic function and behavior in a mouse line harboring a gain-of-function mutation at Serine 270 (S270) in the GABAA receptor alpha1 subunit. In recombinant alpha1beta2gamma2 receptors, replacement of S270 by Histidine (H) results in an increase in sensitivity to gamma-aminobutyric acid (GABA), and slowing of deactivation following transient activation by saturating concentrations of GABA. Heterozygous mice expressing the S270H mutation are hyper-responsive to human contact, exhibit intention tremor, smaller body size and reduced viability. These mice also displayed reduced motor coordination, were hypoactive in the home cage, but paradoxically were hyperactive in a novel open field environment. Heterozygous knockin mice of both sexes were fertile but females failed to care for offspring. This deficit in maternal behavior prevented production of homozygous animals. Recordings from brain slices prepared from these animals revealed a substantial prolongation of miniature inhibitory postsynaptic currents (IPSCs) and a loss of sensitivity to the anesthetic isoflurane, in neurons that express a substantial amount of the alpha1 subunit. The results suggest that the biophysical properties of GABAA receptors are important in determining the time-course of inhibition in vivo, and suggest that the duration of synaptic inhibition is a critical determinant that influences a variety of behaviors in the mouse.

Genetic diversity among sapoviruses

Norovirus and Sapovirus are two genera of the family Caliciviridae that contain viruses that can cause acute gastroenteritis in humans. Noroviruses (NOR) are genetically highly diverse but limited studies of the genetic diversity of sapoviruses (SAP) have been reported. In this study we characterized twenty-five SAP detected in our laboratory from outbreaks or sporadic cases of acute gastroenteritis in children from different geographical locations and in adults involved in a cruise ship outbreak investigation and a nursing home outbreak. Based on significant differences of partial RNA polymerase sequences (278-286 nt), the 25 strains were grouped into 12 genetic clusters, including 9 potential new clusters. Extended sequence analysis of the capsid gene of selected strains representing five potential new clusters supported this grouping. Four strains (Hou7-1181/90, Mex340/90, Cruise ship/00 and Argentina39) had <84% amino acid (aa) identity to each other and to the published sequences in the GenBank. Mex14917/00 was almost identical to Stockholm/97/SE whose RNA polymerase sequence was unknown. Phylogenetic and distance analyses of the capsid region of the four new strains showed that Hou7-1181/90 and Argentina39 represent two new genogroups and Mex340/90 and Cruise ship/00 belong to two new clusters within the London/92 genogroup. Thus, based on the capsid sequences we propose to classify the currently known SAP into nine genetic clusters within five genogroups, including one genogroup that is represented by an animal calicivirus, the porcine enteric calicivirus (PEC).

Chronic ethanol consumption enhances internalization of alpha1 subunit-containing GABAA receptors in cerebral cortex

The molecular mechanisms that underlie ethanol dependence involve alterations in the functional properties and subunit expression of GABAA receptors. Chronic ethanol exposure decreases GABAA receptor alpha1 subunits and increases alpha4 subunit levels in cerebral cortical membranes. This study explored the effect of chronic ethanol exposure on internalization of GABAA/benzodiazepine receptors. Chronic ethanol exposure increased alpha1 subunit levels by 46 +/- 12% and [3H]flunitrazepam binding by 35 +/- 9% in the clathrin-coated vesicle (CCV) fraction. There was a corresponding 34 +/- 8% decrease in alpha1 peptide expression and 37 +/- 6% decrease in [3H]flunitrazepam binding in the synaptic fraction. Chronic ethanol consumption also increased the alpha1 subunit immunoprecipitate in the cytosolic fraction (77 +/- 22%), measured by western blot analysis. Moreover, co-immunoprecipitation of both clathrin and adaptin-alpha with alpha1 subunits was increased in the cytosolic fraction, suggesting that alpha1 subunit endocytosis is enhanced by chronic ethanol consumption. In contrast, alpha4 subunit peptide levels were not altered in the CCV fraction despite a 39 +/- 13% increase in peptide levels in the synaptic fraction of cortex. Moreover, acute ethanol exposure did not alter alpha1 subunit peptide expression or [3H]flunitrazepam binding in the synaptic or CCV fractions. These results suggest that chronic ethanol consumption selectively increases internalization of alpha1 subunit-containing GABAA receptors in cerebral cortex.

Deletion of GABAA receptor alpha 1 subunit-containing receptors alters responses to ethanol and other anesthetics

GABA(A) receptors have been implicated in mediating several acute effects of ethanol including anxiolysis, ataxia, sedation/hypnosis, and anticonvulsant activity. Ethanol sensitivity of neurons has been associated with expression of alpha1 subunit-containing receptors. The objective of this study was to determine the contribution of alpha1 subunit containing receptors to ethanol responses in comparison to neurosteroids and other anesthetics using GABA(A) receptor alpha1 subunit knockout mice. Deletion of alpha1 subunit-containing receptors did not alter the anxiolytic, ataxic, anticonvulsant, or hypnotic effects of ethanol or acute functional tolerance to ethanol but did increase sensitivity to the locomotor-stimulating effects of ethanol. The ability of ethanol to potentiate muscimol-stimulated chloride uptake and ethanol clearance was also not altered following alpha1 subunit deletion. The anticonvulsant and hypnotic effects of neurosteroids as well as their potentiating effect on GABA-mediated Cl(-) uptake were unaltered in alpha1(-/-) mice. The hypnotic effect of pentobarbital, etomidate, and midazolam were reduced, whereas the effect of ketamine was enhanced in alpha1(-/-) mice. Thus, GABA(A) receptor alpha1 subunit-containing receptors appear to influence the motor-stimulating effect of ethanol and the sedative/hypnotic effects of some anesthetics, but not ethanol. These receptors do not appear to be necessary for most ethanol responses, suggesting involvement of other GABA(A) receptor subtypes or other targets altogether.

GABA(A) receptor alpha-1 subunit deletion alters receptor subtype assembly, pharmacological and behavioral responses to benzodiazepines and zolpidem

Potentiation of GABA(A) receptor activation through allosteric benzodiazepine (BZ) sites produces the anxiolytic, anticonvulsant and sedative/hypnotic effects of BZs. Using a mouse line lacking alpha1 subunit expression, we investigated the contribution of the alpha1 subunit to GABA(A) receptor pharmacology, function and related behaviors in response to BZ site agonists. Competitive [(3)H]flunitrazepam binding experiments using the Type I BZ site agonist, zolpidem, and the Type I and II BZ site non-specific agonist, diazepam, demonstrated the complete loss of Type I BZ binding sites in alpha1(-/-) mice and a compensatory increase in Type II BZ binding sites (41+/-6%, P<0.002). Chloride uptake analysis in alpha1(-/-) mice revealed an increase (108+/-10%, P<0.001) in the efficacy (E(max)) of flunitrazepam while the EC(50) of zolpidem was increased 495+/-26% (alpha1(+/+): 184+/-56 nM; alpha1(-/-): 1096+/-279 nM, P<0.01). An anxiolytic effect of diazepam was detected in both alpha1(+/+) and alpha1(-/-) mice as measured on the elevated plus maze; however, alpha1(-/-) mice exhibited a greater percentage of open arm entries and percentage of open arm time following 0.6 mg/kg diazepam. Furthermore, alpha1(-/-) mice were more sensitive to the motor impairing/sedative effects of diazepam (1-10 mg/kg) as measured by locomotor activity in the open field. Knockout mice were insensitive to the anticonvulsant effect of diazepam (1-15 mg/kg, P<0.001). The hypnotic effect of zolpidem (60 mg/kg) was reduced by 66% (P<0.001) in alpha1(-/-) mice as measured by loss of righting reflex while the effect of diazepam (33 mg/kg) was increased 57% in alpha1(-/-) mice (P<0.05). These studies demonstrate that compensatory adaptations in GABA(A) receptor subunit expression result in subunit substitution and assembly of functional receptors. Such adaptations reveal important relationships between subunit expression, receptor function and behavioral responses.

Molecular and pharmacological characterization of GABA(A) receptor alpha1 subunit knockout mice

GABA(A) receptors mediate fast inhibitory neurotransmission in the central nervous system (CNS), and approximately half of these receptors contain alpha1 subunits. GABA(A) receptor alpha1 subunits are important for receptor assembly and specific pharmacological responses to benzodiazepines. Plasticity in GABA(A) receptor alpha1 subunit expression is associated with changes in CNS excitability observed during normal brain development, in animal models of epilepsy, and upon withdrawal from alcohol and benzodiazepines. To examine the role of alpha1 subunit-containing GABA(A) receptors in vivo, we characterized receptor subunit expression and pharmacological properties in cerebral cortex of knockout mice with a targeted deletion of the alpha1 subunit. The mice are viable but exhibit an intention tremor. Western blot analysis confirms the complete loss of alpha1 subunit peptide expression. Stable adaptations in the expression of several GABA(A) receptor subunits are observed in the fifth to seventh generations, including decreased expression of beta2/3 and gamma2 subunits and increased expression of alpha2 and alpha3 subunits. There was no change in alpha4, alpha5, or delta subunit peptide levels in cerebral cortex. Knockout mice exhibit loss of over half of GABA(A) receptors measured by [(3)H]muscimol, [(3)H]2-(3-carboxyl)-3-amino-6-(4-methoxyphenyl)-pyridazinium bromide ([(3)H]SR-95531), and t-butylbicyclophosphoro[(35)S]thionate ([(35)S]TBPS) binding. [(3)H]Ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylate ([(3)H]Ro15-4513) binding is reduced by variable amounts in different regions across brain. GABA(A) receptor alpha1(-/-) mice lose all high-affinity [(3)H]zolpidem binding and about half of [(3)H]flunitrazepam binding in the cerebral cortex. The potency and maximal efficacy of muscimol-stimulated (36)Cl(-) uptake in cerebral cortical synaptoneurosomes are reduced in alpha1(-/-) mice. Furthermore, knockout mice exhibit increased bicuculline-induced seizure susceptibility compared with wild-type mice. These data emphasize the significance of alpha1 subunit expression and its involvement in the regulation of CNS excitability.

From bioactive substances to research on breast-feeding promotion

Despite known health benefits, exclusive breast-feeding for at least 4 months is uncommon in many countries. In Mexico, most mothers initiate breast-feeding but few breast-feed exclusively.

OBJECTIVE

The objective was to examine the effectiveness of home visits by lay peer counselors to increase exclusive breast-feeding among mothers in a periurban area of Mexico.

METHODS

An ethnographic assessment conducted in 1994 that identified key maternal beliefs, practices, and needs was used to guide educational strategies. Lay counselors were recruited from the same community and trained by La Leche League. From March 1995 through September 1996, pregnant women were identified by community census and invited to participate. Women were enrolled into a randomized, controlled study of 3 groups: no intervention (control), 3 visits, and 6 visits during pregnancy and early postpartum. Data collection was performed by a social worker apart from the counselors. Exclusive breast-feeding was defined by WHO criteria.

RESULTS

The study enrolled 130 women; 52 were in the 3-visit group, 44 in the 6-visit group, and 34 in the control group. Study groups did not differ in the maternal characteristics or initiation of breast-feeding (96%). At 3 months postpartum, exclusive breast-feeding was practiced by only 12% of controls vs. 52% in the 3-visit group and 67% in the 6-visit group (P < 0.001, log rank test). In the first 3 months, significantly (P = 0.037) fewer intervention than control infants had an episode of diarrhea (11% vs. 26%, respectively). Intervention effectiveness was independent of maternal factors or birth hospital.

CONCLUSIONS

This unique experimental study demonstrated a dramatic increase in exclusive breast-feeding and a significant reduction in infant illness in an urban community through well-designed maternal support including early intervention and repeated contact.

GABA(A)-receptor delta subunit knockout mice have multiple defects in behavioral responses to ethanol

BACKGROUND

The gamma-aminobutyric acid type A receptors (GABARs) are involved in mediating some of the behavioral effects of beverage alcohol (ethanol). However, the unique pharmacological and behavioral responses conferred by each of the various receptor subunits are not well understood.

METHODS

To address the role of the GABAR delta subunit in mediating ethanol responses, gene knockout mice that lack this subunit were tested for a variety of ethanol-induced behavioral responses.

RESULTS

Our results indicate that, compared with controls, delta-deficient mice (delta-/-) have (1) reduced ethanol consumption, (2) attenuated withdrawal from chronic ethanol exposure, and (3) reduced anticonvulsant (seizure-protective) effects of ethanol. These mice demonstrate a normal anxiolytic response to ethanol and a normal hypothermic response to ethanol, and they develop both chronic and acute tolerance.

CONCLUSIONS

These results further establish the link between GABARs and specific behavioral responses to ethanol and begin to reveal the role of the delta subunit in these responses.

3Alpha-hydroxy-5alpha-pregnan-20-one levels and GABA(A) receptor-mediated 36Cl(-) flux across development in rat cerebral cortex

Despite considerable evidence showing dramatic changes in the plasticity of GABA(A) receptors during neuronal development and studies showing a direct link between neurosteroid concentrations and alterations in GABA(A) receptor expression, little is known about the role of neurosteroids in GABA(A) receptor plasticity early in development. The relationship between changes in brain concentrations of 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone, 3alpha,5alpha-THP) and GABA(A) receptor function in the brain during early development was investigated in rats. The concentration in fetal forebrain of the pregnane metabolite 3alpha,5alpha-THP declined precipitously prior to parturition, before returning to normal (adult male) values on the day of birth (P0). Postnatal cortical 3alpha,5alpha-THP levels remain quite low (<2 ng/g) until postnatal day 10 (PD10) and PD14 when we found elevated cortical 3alpha,5alpha-THP levels (3.3+/-0.8 and 3.8+/-0.9 ng/g, respectively). These levels reverted to basal values by PD15 (0.56+/-0.4 ng/g). We examined GABA(A) receptor-mediated 36Cl(-) flux in cortex of PD7, PD12 and PD16 rat brain. We found a 32% reduction in the stimulation (apparent E(max)) of 36Cl(-) uptake by muscimol in PD12 tissue relative to adult. The potentiating effects of 3alpha,21-dihydroxy-5alpha-pregnane-20-one (tetrahydrodeoxycorticosterone, THDOC) and flunitrazepam were decreased in PD12 tissue. These data provide a better understanding of potential contributions endogenous GABAergic neurosteroids may make to normal neuronal development.

Age-related differences in neurosteroid potentiation of muscimol-stimulated 36Cl(-) flux following chronic ethanol treatment

Alcoholism and alcohol abuse create costly social and economic problems in many nations. Recent studies indicate that alcohol exposure during adolescence may convey unique risks for subsequent neurocognitive deficits and problem drinking. Although GABA(A) receptor function is one of the principle neurochemical targets of ethanol action in the adult brain, little is known about the effects of alcohol on this system during adolescence. Adolescent (30-day-old) and adult (90-day-old) male rats were intermittently exposed to ethanol for 1 month. At various times after the end of the exposure period, synaptoneurosomes were prepared from their cerebral cortices. GABA(A) receptor-mediated 36Cl(-) influx was measured in the absence and presence of the neurosteroid 3alpha,21-dihydroxy-5alpha-pregnan-20-one (THDOC). In tissue from ethanol-exposed animals, sensitization to the potentiating effects of the neurosteroid was apparent 5 and 12 days after ethanol withdrawal. This sensitization was more apparent at the low concentrations of THDOC in animals pretreated with ethanol as adolescents. Sensitization to the potentiating effects of a neurosteroid is an enduring phenomenon, persistent long after the acute phase of ethanol withdrawal, and may be indicative of long-term changes in GABA(A) receptor function. Enhanced neurosteroid sensitization in animals pretreated as adolescents is consistent with the notion that adolescence is a period of unique sensitivity to the effects of ethanol. This uniqueness may now be extended to the chronic effects of ethanol.

The role of GABAergic neuroactive steroids in ethanol action, tolerance and dependence

This article reviews data on ethanol and neurosteroid interactions in the CNS. We discuss how GABAergic neurosteroids, including 3alpha,5alpha-TH PROG and 3alpha,5alpha-TH DOC, produced in response to systemic ethanol administration contribute to several of the effects of ethanol associated with modulation of GABA(A) receptors in rodents. There is an essential correlation between the time course of ethanol-induced 3alpha,5alpha-TH PROG production in the brain and specific behavioral and neural effects of ethanol. Furthermore, the anticonvulsant and inhibitory effects of ethanol on spontaneous neural activity were completely prevented by a key inhibitor of steroid biosynthesis. 3alpha,5alpha-TH PROG influences cognitive processing, spatial learning and memory and alters drinking behaviors in rats. Furthermore, ethanol induction of 3alpha,5alpha-TH PROG is diminished in tolerant and dependent animals. These effects are associated with increases in the sensitivity of GABA(A) receptors to neurosteroids and suggest an important role in ethanol withdrawal. Together, we suggest that 3alpha,5alpha-TH PROG and 3alpha,5alpha-TH DOC contribute to ethanol action and this interaction may represent a new mechanism of ethanol action. The identification of neurosteroid intermediaries involved in ethanol action may lead to important advances in the field and the development of novel therapeutics for alcoholism.

Chronic ethanol consumption differentially alters GABA(A) receptor alpha1 and alpha4 subunit peptide expression and GABA(A) receptor-mediated 36 Cl(-) uptake in mesocorticolimbic regions of rat brain

BACKGROUND

Gamma-aminobutyric acid type A (GABA(A)) receptors in the brain are modulated by chronic ethanol exposure via the regulation of their function and expression throughout the central nervous system. Recent studies show that chronic ethanol exposure alters subsequent ethanol self-administration, effects that are believed to be mediated by subcortical regions of the rat brain including the amygdala (AMG), the nucleus accumbens (NAC), and the ventral tegmental area (VTA).

METHODS

We evaluated GABA(A) receptor subunit expression using subunit specific (alpha1 and alpha4) immunoblotting of small tissue punches from AMG, NAC, and VTA. GABA(A) receptor-mediated 36 Cl- uptake was measured in these brain areas after chronic ethanol consumption for 2 weeks.

RESULTS

Regional differences in the effect of chronic ethanol on alpha1 and alpha4 subunit expression were found. In the AMG, alpha1 and alpha4 subunit expressions were significantly decreased by 21.1 +/- 5.5% and 22.0 +/- 7.1%, respectively. In the NAC, there was a decrease of 28.1 +/- 1.3% in alpha4 subunit expression (p < 0.0001), but no change in alpha1 subunit expression was observed. In the VTA, there were no changes in alpha1 and alpha4 subunit expressions. Muscimol-stimulated Cl- uptake was enhanced in the extended AMG, but not the extended NAC of ethanol-dependent rats. The muscimol concentration response curve was left-shifted with a 74% decrease (p < 0.01) in the EC50 and a 42% increase (p < 0.05) in the Emax in the AMG of ethanol-dependent rats.

CONCLUSIONS

These results suggest that chronic ethanol exposure alters GABA(A) receptor expression in the AMG and NAC. Decreased expression of alpha4 subunits is associated with increases in GABA(A) receptor function in the AMG, but not the NAC. These changes may contribute to alcohol drinking behavior and the development of ethanol dependence.

Asthma and obesity in adolescents: is there an association?

To determine if obesity is more prevalent in adolescents with asthma compared with nonasthmatic adolescents and to determine if obesity is associated with more severe asthma, we studied 265 adolescent asthmatics 12-21 years of age and 482 nonasthmatic adolescents. The prevalence of obesity in the asthmatic group was 20% compared to 17% in the control group. The prevalence of being at risk of overweight was similar for asthmatics (16%) and controls (15%). The prevalence of obesity in moderate to severe asthmatics (21%) was not different from prevalence of obesity in mild asthmatics (19%) or controls (17%). In this study of primarily African-American urban adolescents, obesity was not associated with asthma or more severe asthma.

GABA(A) receptor alpha1 subunit deletion prevents developmental changes of inhibitory synaptic currents in cerebellar neurons

Developmental changes in miniature IPSC (mIPSC) kinetics have been demonstrated previously in cerebellar neurons in rodents. We report that these kinetic changes in mice are determined primarily by developmental changes in GABA(A) receptor subunit expression. mIPSCs were studied by whole-cell recordings in cerebellar slices, prepared from postnatal day 11 (P11) and P35 mice. Similar to reports in granule neurons, wild-type cerebellar stellate neuron mIPSCs at P11 had slow decay kinetics, whereas P35 mIPSCs decayed five times faster. When mIPSCs in cerebellar stellate neurons were compared between wild-type (+/+) and GABA(A) receptor alpha1 subunit-deficient (-/-) littermates at P35, we observed dramatically slower mIPSC decay rates in -/- animals. We took advantage of the greater potency of imidazopyridines for GABA current potentiation with alpha1 subunit-containing receptors to characterize the relative contribution of alpha1 subunits in native receptors on inhibitory synapses of cerebellar granule neurons. Zolpidem-induced prolongation of mIPSC decay was variable among distinct cells, but it increased during development in wild-type mice. Similarly, Zolpidem prolongation of mIPSC decay rate was significantly greater in adult +/+ mice than in knock-outs. We propose that an increased alpha1 subunit assembly in postsynaptic receptors of cerebellar inhibitory synapses is responsible for the fast inhibitory synaptic currents that are normally observed during postnatal development.

Fucosylated human milk oligosaccharides vary between individuals and over the course of lactation

Specific human milk oligosaccharides, especially fucosylated neutral oligosaccharides, protect infants against specific microbial pathogens. To study the concentrations of individual neutral oligosaccharides during lactation, a total of 84 milk samples were obtained from 12 women at 7 time periods during weeks 1-49 postpartum. The neutral oligosaccharides from each sample were isolated, perbenzoylated, resolved, and quantified by reversed-phase high-performance liquid chromatography. The resultant oligosaccharide peaks, identified by co-elution with authentic standards and mass spectrometry, ranged in size from tri- to octasaccharides. The total concentration of oligosaccharides declined over the course of lactation; the mean concentration at 1 year was less than half that in the first few weeks postpartum. One of the 12 donors produced milk fucosyloligosaccharides that were essentially devoid of alpha1,2 linkages (but contained alpha1,3- and alpha1,4-linked fucose) until late in lactation, consistent with the nonsecretor phenotype. In milk samples from the remaining 11 donors, fucosyloligosaccharides containing alpha1,2-linked fucose were prevalent, and their profiles were distinct from those of fucosyloligosaccharides devoid of alpha1,2-linked fucose. The ratio of alpha1,2-linked oligosaccharide concentrations to oligosaccharides devoid of alpha1,2-linked fucose changed during the first year of lactation from 5:1 to 1:1. Furthermore, the absolute and the relative concentrations of individual oligosaccharides varied substantially, both between individual donors and over the course of lactation for each individual. The patterns of milk oligosaccharides among individuals suggest the existence of many genotype subpopulations. This variation in individual oligosaccharide concentrations suggests that the protective activities of human milk could also vary among individuals and during lactation.

Allopregnanolone levels and reactivity to mental stress in premenstrual dysphoric disorder

BACKGROUND

This study was designed to examine basal and stress-induced levels of the neuroactive progesterone metabolite, allopregnanolone, in women with premenstrual dysphoric disorder (PMDD) and healthy control subjects. Also, because evidence suggests that allopregnanolone negatively modulates the hypothalamic-pituitary-adrenal axis, plasma cortisol levels were examined. An additional goal was to investigate the relationship between premenstrual symptom severity and luteal phase allopregnanolone levels.

METHODS

Twenty-four women meeting prospective criteria for PMDD were compared with 12 controls during both the follicular and luteal phases of confirmed ovulatory cycles, counterbalancing phase at first testing. Plasma allopregnanolone and cortisol were sampled after an extended baseline period and again 17 min following the onset of mental stress. Owing to low follicular phase allopregnanolone levels, only luteal phase allopregnanolone and cortisol were analyzed.

RESULTS

During the luteal phase, PMDD women had significantly greater allopregnanolone levels, coupled with significantly lower cortisol levels, during both baseline and mental stress. Moreover, significantly more controls (83%) showed the expected stress-induced increases in allopregnanolone compared with PMDD women (42%). Premenstrual dysphoric disorder women also exhibited a significantly greater allopregnanolone/progesterone ratio than control subjects, suggesting alterations in the metabolic pathways involved in the conversion of progesterone to allopregnanolone. Finally, PMDD women with greater levels of premenstrual anxiety and irritability had significantly reduced allopregnanolone levels in the luteal phase relative to less symptomatic PMDD women. No relationship between symptom severity and allopregnanolone was observed in controls.

CONCLUSIONS

These results suggest dysregulation of allopregnanolone mechanisms in PMDD and that continued investigations into a potential pathophysiologic role of allopregnanolone in PMDD are warranted.

Effects of sweetened ethanol solutions on ethanol self-administration and blood ethanol levels

The enhancement of voluntary self-administration of ethanol by sucrose or saccharin was tested in conjunction with measurements of blood ethanol levels. Adult male rats were given access to both tap water and one of five solutions: 0.125% saccharin, 10% sucrose, ethanol, saccharin+ethanol, or sucrose+ethanol. The rats receiving the sucrose+ethanol solution drank consistently more ethanol (>5 g/kg/day) than did the rats receiving the saccharin+ethanol solution (<3 g/kg/day) or ethanol only (<2 g/kg/day). Both sweetened solutions produced higher ethanol consumption during these periods than ethanol alone. However, no significant differences in blood ethanol levels were found between the sucrose+ethanol and saccharin+ethanol conditions, when tested at different intervals on Day 44 or Day 45 of ethanol consumption. Following 45 days of consumption, no change in the bicuculline seizure threshold was observed in the ethanol-consuming rats compared to the controls. In a separate study using 90 naive rats, rats were gavaged with ethanol (1, 2, or 3 g/kg) containing either 10% sucrose (n=10 for each dose of ethanol), 0.125% saccharin (n=10 for each dose of ethanol), or ethanol alone (n=10 for each dose of ethanol), and blood was collected from the tip of the tail 30, 60, 180, 300, and 540 min later and analyzed for ethanol concentrations. Sucrose significantly decreased the resultant blood ethanol levels at several time points following gavage. These results indicate that sucrose can significantly alter blood ethanol levels and that chronic self-administration of a sweetened ethanol solution for 6 weeks does not produce ethanol dependence.

3alpha-hydroxy-5alpha-pregnan-20-one exposure reduces GABA(A) receptor alpha4 subunit mRNA levels

To examine the direct effects of neurosteroids on gamma-aminobutyric acid type A (GABA(A)) receptor expression, we exposed developing neuronal cells (P19) in vitro to 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP, allopregnanolone). Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed a concentration-dependent decrease in GABA(A) receptor alpha4 subunit mRNA expression that reversed 24 h after steroid withdrawal. These data suggest that variations in neurosteroid levels regulate the pattern of GABA(A) receptor subunit expression and may alter the trophic effects of GABA.

Serum antibody as a marker of protection against natural rotavirus infection and disease

To determine whether naturally acquired serum IgA and IgG antibodies were associated with protection against rotavirus infection and illness, a cohort of 200 Mexican infants was monitored weekly for rotavirus excretion and diarrhea from birth to age 2 years. Serum samples collected during the first week after birth and every 4 months were tested for anti-rotavirus IgA and IgG. Children with an IgA titer >1:800 had a lower risk of rotavirus infection (adjusted relative risk [aRR], 0.21; P<.001) and diarrhea (aRR, 0. 16; P=.01) and were protected completely against moderate-to-severe diarrhea. However, children with an IgG titer >1:6400 were protected against rotavirus infection (aRR, 0.51; P<.001) but not against rotavirus diarrhea. Protective antibody titers were achieved after 2 consecutive symptomatic or asymptomatic rotavirus infections. These findings indicate that serum anti-rotavirus antibody, especially IgA, was a marker of protection against rotavirus infection and moderate-to-severe diarrhea.

Regional variations in the effects of chronic ethanol administration on GABA(A) receptor expression: potential mechanisms

Gamma-aminobutyric acid type A (GABA(A)) receptors in brain adapt to chronic ethanol exposure via changes in receptor function and subunit expression. The present review summarizes currently available data regarding changes in GABA(A) receptor subunit mRNA and peptide expression. Data are presented from various different brain regions and the variations between specific brain regions used to draw conclusions about mechanisms that may underlie GABA(A) receptor adaptations during chronic ethanol exposure. In the whole cerebral cortex, chronic ethanol exposure leads to a reduction of GABA(A) receptor alpha1 subunit mRNA and peptide levels and a near equivalent increase in alpha4 subunit mRNA and peptide levels. This observation is the primary support for the hypothesis that altered receptor composition is a mechanism for GABA(A) receptor adaptation produced by chronic ethanol exposure. However, other brain regions do not display similar patterns of subunit changes. Moreover, subregions within cortex (prefrontal, cingulate, parietal, motor, and piriform) exhibit patterns of changes in subunit expression that differ from whole cortex. Therefore, regional differences in GABA(A) receptor subunit expression are evident following chronic ethanol administration, thus suggesting that multiple mechanisms contribute to the regulation of GABA(A) receptor expression. These mechanisms may include the involvement of other neurotransmitter systems, endogenous steroids and second or third messenger cross-talk.

Ovariectomy has minimal effects on neuroadaptations associated with ethanol dependence in female rats

We previously found gender selective alterations in gene expression for GABA(A) and NMDA receptors associated with the development of ethanol dependence. Males and females have a differing hormonal environment, including steroid hormone derivatives (neuroactive steroids) that exert effects at GABA(A) and NMDA receptors. Therefore, we explored whether the removal of ovarian steroids would alter gender differences in response to chronic ethanol exposure. We found that ovariectomy reduced ethanol drinking levels by 15%, comparable to earlier observations between intact female and male rats. However, investigation of the effects of chronic ethanol exposure on intact versus ovariectomized female rats uncovered few differences in chronic ethanol-induced alterations in selected GABA(A) or NMDA receptor subunit peptide levels. In general, findings for both groups of females were similar to previous observations. There was no reduction in GABA(A) receptor alpha1 subunit levels in cerebral cortex in either intact or ovariectomized female rats, in contrast to the significant reduction observed in male rats. In addition, both intact and ovariectomized female rats had increased levels of the NMDA NR1 subunit in cerebral cortex and hypothalamus, but not in hippocampus, whereas ethanol dependent male rats displayed significant increases in the NR1 subunit only in hippocampus. Radioligand binding analysis with [35S]TBPS found no differences in modulation of the GABA(A) receptor by neuroactive steroids between ethanol dependent male, intact female or ovariectomized female rats. Seizure susceptibility was not different between intact or ovariectomized female rats during ethanol withdrawal. We did observe differential effects on brain allopregnanolone and plasma corticosterone levels between ethanol dependent intact and ovariectomized female rats, suggesting that ovarian steroids influence HPA axis adaptations to prolonged ethanol exposure. Overall, these data suggest that ovarian steroids do not significantly impact the gender selective alterations of GABA(A) and NMDA receptors associated with ethanol dependence.

Transient increase in cerebellar transcriptional activity precedes the expression of GABA(A) receptor alpha6 subunit mRNA during postnatal maturation

The purpose of this study was to investigate the postnatal expression of GABA(A) receptor alpha6 subunit genes in the context of cerebellar differentiation. We examined steady-state levels of GABA(A) receptor alpha1 and alpha6 subunit mRNAs, polyadenylated (polyA+) mRNA and beta-actin mRNA in7-, 14-, 21-, 28-, 35-, 49- and 120-day-old rats. Messenger RNA expression and splicing were evaluated in parallel using Northern blot analysis and in situ hybridization histochemistry. The expression of mature GABA(A) receptor alpha6 subunit mRNA species (2.7 kb) was found 1 week after birth in cerebellar granule cells. Prior to stable expression of the mature alpha6 subunit gene, we detected large alpha6 subunit premessengers (3.8 and 3.5 kb) by Northern blot analysis. These premessenger species were detected in prenatal day (PND) 15 and neonatal rat cerebellum, when the mature alpha6 subunit mRNAs (2.7 kb) were not yet expressed. The maximal expression of mature alpha6 subunit mRNA species was observed at PND 21 when the peak level of cerebellar transcriptional activity was measured by polyA+ RNA levels. In contrast, beta-actin mRNA expression was decreased at PND 21 compared to birth levels. These major transcriptional events take place during a period of about 1 week (between PND 14 and 21), immediately following the most active phase of cell division in the external granule layer and migration of granule cells to the internal granule cell layer. Comparison between the relative abundance of these genes shows that differential regulation of each gene occurs during postnatal development. The induction of GABA(A) receptor alpha6 subunit gene expression is preceded by a reduction in beta-actin mRNA levels and a transient increase in total transcriptional activity. The expression of alpha6 subunit mRNA is maintained at the PND 21 level through adulthood, but the alpha1 subunit mRNA levels decrease drastically within the following week (from PND 21 to 28). These results suggest that tissue-specific expression of the GABA(A) receptor alpha6 subunit gene is correlated with a series of developmentally regulated morphologic and transcriptional events.

Prenatal exposure to the pesticide dieldrin or the GABA(A) receptor antagonist bicuculline differentially alters expression of GABA(A) receptor subunit mRNAs in fetal rat brainstem

We have previously shown that GABA acts as a trophic signal for monoamine neurons in embryonic day 14 (E14) rat brainstem cultures [Liu et al., J Neurosci 1997a; 17:2420-2428]. The organochlorine pesticide dieldrin and the classical GABA(A) receptor antagonist bicuculline interfere with the trophic actions of GABA and alter expression of several GABA(A) receptor subunit mRNA transcripts in these cultures [Liu et al., J Neurosci Res 1997b;49:645-653]. In the present study, we investigated whether prenatal exposure to dieldrin or bicuculline from E12-17 would alter mRNA expression of alpha1, beta3, gamma1, gamma2S and gamma2L GABA(A) receptor subunits in fetal (E17) rat brainstem using competitive RT-PCR to absolutely quantify these transcripts. The effects of dieldrin and bicuculline on expression of GABA(A) receptor subunit transcripts were similar across subunits. Dieldrin and bicuculline decreased expression of alpha1, beta3 and gamma1 transcripts compared to vehicle-injected controls, but did not significantly alter expression of gamma2S and gamma2L transcripts. Taken together, these studies indicate that in utero exposure to organochlorine pesticides acting as GABA(A) receptor antagonists may alter the expression and subunit composition of developing GABA(A) receptors. If these changes persist, they could have long-lasting effects on developing GABAergic neural circuitry, GABA(A) receptor function and GABA-mediated behaviors.

Chronic ethanol consumption alters recovery of spontaneously active medial septal/diagonal band of broca neurons from GABA-microiontophoresis

BACKGROUND

Acute ethanol administration increases GABA-mediated inhibition in a variety of cerebral cortical preparations. Furthermore, chronic ethanol administration blunts ethanol-induced increases in GABA-mediated inhibition and alters GABA A receptor subunit mRNA and peptide expression in the cerebral cortex. The sedative hypnotic effects of ethanol are believed to be modulated by GABA-induced inhibition in medial septum/diagonal band of Broca (MS/DB) neurons, a brain region where acute ethanol administration increases GABA-mediated inhibition of spontaneously active neurons. Chronic ethanol administration produces tolerance to the sedative effects of ethanol. However, it is unknown if chronic ethanol consumption produces alterations in GABA-mediated inhibition in the MS/DB in a manner similar to that found in the cerebral cortex.

METHODS

Animals either consumed ethanol chronically for 14 days via a liquid diet or were pair-fed an equicaloric dextrose-containing control diet. Spontaneously active MS/DB neurons were recorded using multibarrel glass micropipettes while the effect of GABA-microiontophoresis was investigated. The total amount of GABA-mediated inhibition at four ejection currents was analyzed, as was the recovery to spontaneous neural firing rates following GABA inhibition. In a separate group of animals, the medial septum was microdissected, and the relative expression of GABA A receptor alpha1 and alpha4 subunit peptide were analyzed via Western blot analysis.

RESULTS

Chronic ethanol consumption altered recovery of spontaneous neural activity of MS/DB neurons following GABA-microiontophoresis compared to premicroiontophoresis levels. Specifically, the recovery of spontaneous neural activity of MS/DB neurons recorded from animals that chronically consumed ethanol was slower following GABA-microiontophoresis compared to neurons recorded from control animals. This effect was temporary and reversible. Furthermore, the alteration in recovery of spontaneous neural activity was not due to changes in the total amount of inhibition produced by GABA. Finally, there was no significant change in GABA A receptor alpha1 and alpha4 subunit peptide levels in the MS/DB.

CONCLUSIONS

Chronic ethanol consumption alters the frequency of spontaneous MS/DB neural activity following GABA microiontophoresis compared to premicroiontophoresis levels. These data suggest that the kinetics of GABA A receptors in the MS/DB are altered by chronic ethanol consumption independent of changes in the total amount of inhibition or alterations in GABA A receptor alpha1 and alpha4 subunit peptide expression.

Chronic ethanol administration alters immunoreactivity for GABA(A) receptor subunits in rat cortex in a region-specific manner

BACKGROUND

Chronic ethanol administration has a plethora of physiological effects. Among the most consistently observed findings is a change in the expression pattern of gamma-aminobutyric acid type A (GABA(A)) receptor subunits in the rat brain cortex. These findings led to the hypothesis of "subunit substitution" to account for changes in receptor function without changes in receptor number.

METHODS

We used subunit (alpha1 and alpha4) specific antibodies and a combination of immunohistochemistry and immunoblotting to examine subregions of cortex (prefrontal, cingulate, motor, parietal, and piriform) for their response to 2 weeks of forced ethanol administration.

RESULTS

Overall, cortical immunoreactivity for the alpha1 subunit was decreased and for the alpha4 subunit increased whether measured immunohistochemically or by immunoblotting. Piriform cortex exhibited a bidirectional change in GABA(A) receptor alpha1 and alpha4 immunoreactivity, similar to that previously observed in preparations of whole cortex. However, in parietal cortex, declines in alpha1 immunoreactivity (55 +/- 12% control value [CV] and 88.3 +/- 4.3% CV; immunohistochemistry and immunoblotting, respectively) were not accompanied by concomitant increases in alpha4 immunoreactivity (104 +/- 8% CV and 116 +/- 9.3% CV; immunohistochemistry and immunoblotting, respectively). Conversely, alpha4 immunoreactivity increased in cingulate cortex (210 +/- 30% CV and 134 +/- 9.5% CV; immunohistochemistry and immunoblotting, respectively) without a decline in alpha1 immunoreactivity (90 +/- 4% CV and 91.3 +/- 3.9% CV; immunohistochemistry and immunoblotting, respectively). Prefrontal and motor cortex exhibited GABA(A) receptor subunit peptide alterations, but these changes varied with the method of analysis.

CONCLUSIONS

These findings demonstrate that ethanol dependence results in nonuniform changes in GABA(A) receptor subunit peptide levels across the rat brain cortex and suggest that mechanisms which subserve functional changes in receptor activity may vary in accordance with anatomic or cellular differences within the cortex.

Neurosteroid modulation of embryonic neuronal survival in vitro following anoxia

Neurosteroids are synthesized de novo in the brain from cholesterol or peripheral steroid precursors and modulate inhibitory gamma-aminobutyric acid (GABA(A)) and excitatory N-methyl-D-aspartate (NMDA) receptors. Evidence indicates that neurosteroids are neuroprotective and important during neurodevelopment. We tested the hypothesis that neurosteroids increase embryonic neuronal survival following anoxia in rat embryonic day 18 cerebral cortical cultures to examine potential neurosteroid modulation of this insult during early development. Twenty-four hours after plating in serum-free medium, cultures were exposed to DHEA, DHEAS, or allopregnanolone (10(-10), 10(-8), or 10(-6) M), or vehicle, for 24 h (n=9 per treatment condition). Cultures were then subjected to anoxia for 2 h and subsequently reincubated for 24 h prior to neuron immunostaining with microtubule-associated protein 2 (MAP-2) antibody. Supernatant from DHEA and DHEAS-exposed cultures was tested for 17beta-estradiol metabolite formation by radioimmunoassay. DHEA 10(-6) and 10(-8) M significantly increased neuron survival by 85-87% following anoxia. DHEAS 10(-6) M significantly increased neuron survival by 74% following anoxia, but DHEAS 10(-10) M decreased neuron survival after this insult. Allopregnanolone had modest effects on neuron survival that did not attain statistical significance. 17beta-Estradiol concentrations were below the limit of detection in all specimens tested (sensitivity 4.7 nM). Our data indicate that pretreatment with DHEA and DHEAS at physiologically relevant concentrations promotes neuronal survival following anoxia in embryonic rat cerebral cortical cultures, and that these effects are not secondary to 17beta-estradiol metabolite formation. DHEA and DHEAS modulation of anoxia in embryonic neurons may be relevant to disorders of neurodevelopment involving this insult.

Effect of method of defining the active patient population on measured immunization rates in predominantly Medicaid and non-Medicaid practices

OBJECTIVE

To examine the effect of patient selection criteria on immunization practice assessment outcomes.

METHODS

In 3 high- (50%-85%) and 7 low- (<25%) Medicaid pediatric practices in urban eastern Virginia, we assessed immunization rates of children 12 and 24 months old comparing the standard criteria (charts in the active files excluding those that documented the child moved or went elsewhere) with 3 alternative criteria for selecting active patients: 1) follow-up: the chart contained a complete immunization record or the patient was found to be active in the practice through follow-up contact by phone or mail; 2) seen in the past year: the chart indicated that the patient was seen in the practice in the past year; 3) consecutive: patients that were seen consecutively for any reason.

RESULTS

Of the 1823 charts assessed in the high- and low-Medicaid practices, follow-up identified 61% and 83% as active patients; 78% and 95% were ever seen in the past year. At 24 months, mean practice immunization rates were lower for standard (70%) than all 3 alternative criteria (78%-86%). Immunization rate differences between standard and alternative criteria were greater in high- (17%-23%) than low-Medicaid practices (5%-13%).

CONCLUSION

The standard for practice assessment should be based on a consistent definition of active patients as the immunization rate denominator.

Pharmacological characterisation of cortical gamma-aminobutyric acid type A (GABAA) receptors in two Wistar rat lines selectively bred for high and low anxiety-related behaviour

Two Wistar rat lines that have been selectively bred for high-anxiety-related behaviour (HAB) and low-anxiety-related behaviour (LAB) in the elevated plusmaze test may be considered as a genetically prone animal model to study the neurochemical correlates of anxiety-related behaviour. Because there are pronounced differences between the two lines both in baseline levels of open-arm exploration in the elevated plus-maze test and in sensitivity to the anxiolytic effects of 1 mg/kg diazepam, we used these lines to investigate the pharmacology of the benzodiazepine binding site and the GABA binding site of cortical GABAA receptors. No difference in characteristics of flunitrazepam, zolpidem or muscimol binding to cortical GABAA receptors could be detected between the two lines. Although there was an increase in the brain concentration of the anxiolytic neuroactive steroid allopregnanolone, a potent positive allosteric modulator of GABAA receptors, both in HAB and LAB animals after a forced swim stress, allopregnanolone concentrations did not differ between the two lines. Moreover, plasma dehydroepiandrosterone (DHEA) concentrations were similar in HAB and LAB animals. We conclude that anxiety-related behaviour and benzodiazepine sensitivity in these rat lines are likely to be independent of the pharmacology of cortical GABAA receptors.

Olanzapine increases allopregnanolone in the rat cerebral cortex

BACKGROUND

The neurosteroid allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one) has anxiolytic and anticonvulsant properties, potentiating GABA(A) receptor chloride channel function with 20-fold higher potency than benzodiazepines. Behavioral studies demonstrate that olanzapine has anxiolyticlike properties in animals, but the mechanism responsible for these effects is not clear. We examined the effect of acute olanzapine administration on cerebral cortical allopregnanolone and its relationship to serum progesterone and corticosterone levels in rats.

METHODS

Male Sprague-Dawley rats were habituated to intraperitoneal (IP) saline injection for 5 days. On the day of the experiment, rats were injected with olanzapine (0, 2.5, 5.0, or 10.0 mg/kg IP, 10-11 rats per condition). Rats were sacrificed 1 hour later, and cerebral cortical allopregnanolone levels and serum progesterone and corticosterone levels were measured by radioimmunoassay.

RESULTS

Olanzapine increases cerebral cortical allopregnanolone up to fourfold, depending on dose. Positive correlations were observed between cerebral cortical allopregnanolone and serum progesterone levels and between cerebral cortical allopregnanolone and serum corticosterone levels.

CONCLUSIONS

Olanzapine-induced increases in the potent GABA(A) receptor modulator allopregnanolone may alter GABAergic neurotransmission, possibly contributing to antipsychotic efficacy. If allopregnanolone alterations are linked to psychotic symptom relief, neurosteroids may represent molecules for pharmacologic intervention.

Does candidemia predict threshold retinopathy of prematurity in extremely low birth weight (</=1000 g) neonates?

BACKGROUND

Extreme prematurity is a risk factor for both candidemia and threshold retinopathy of prematurity (ROP) and may confound the reported association between these conditions.

OBJECTIVE

To determine if candidemia is an independent risk factor for threshold ROP.

METHODS

A cohort study was conducted of infants weighing </=1000 g at birth using a prospectively maintained neonatal database. The study included infants admitted to the neonatal intensive care unit at </=3 days of age between January 1, 1993 and December 31, 1997. We excluded infants not screened for ROP because they died, were discharged, or transferred. Threshold ROP (ie, requiring ablative therapy within 72 hours of diagnosis) was defined by the criteria of the American Academy of Pediatrics Section on Ophthalmology ROP subcommittee. Candidemia was defined as Candida species growth from at least 1 blood culture. Cox proportional hazards regression was used to determine independent risk factors for threshold ROP.

RESULTS

Six hundred fourteen infants weighing </=1000 g at birth, of which 165 were excluded: 120 died before ROP screening, 40 were admitted >3 days of age, and 5 were discharged or transferred before ROP screening. A total of 449 infants were included in the study; 58 (13%) developed threshold ROP. Candidemia occurred in 58 (13%) infants before developing the worst stage of ROP. Candidemia occurred in 27 of 73 (37%) at 23 to 24 weeks' gestational age (GA), 25 of 197 (13%) at 25 to 26 weeks' GA, and 6 of 129 (5%) at 27 to 28 weeks' GA, 0 of 50 >28 weeks' GA. Similarly, threshold ROP occurred in 25 of 73 (34%) at 23 to 24 weeks' GA, 26 of 197 (13%) at 25 to 26 weeks' GA, and 6 of 129 (5%) at 27 to 28 weeks' GA, and 1 of 50 (2%) >28 weeks' GA. Threshold ROP developed in 19 of 58 (33%) infants with a history of candidemia and 39 of 391 (10%) without candidemia. Proportional hazards analysis indicated that GA in weeks (hazard ratio =.75; 95% confidence interval [CI]:. 61,.93) and non-black ethnicity (hazard ratio = 1.8; 95% CI: 1.05, 3. 08) were significantly associated with threshold ROP. After controlling for GA and other factors, candidemia did not remain significantly associated with threshold ROP (hazard ratio = 1.6; 95% CI:.89, 2.89).

CONCLUSION

Candidemia may not be an independent risk factor for threshold ROP in extremely low birth weight infants. The magnitude of the previously reported association between candidemia and threshold ROP (more than fivefold) is unlikely and much of the clinically observed association appears to be mediated by gestational age.

Outcomes evaluation of a comprehensive intervention program for asthmatic children enrolled in medicaid

OBJECTIVES

To evaluate health care and financial outcomes in a population of Medicaid-insured asthmatic children after a comprehensive asthma intervention program.

DESIGN

Controlled clinical trial.

SETTING

Pediatric allergy clinic in an urban, tertiary care children's hospital.

SUBJECTS

Eighty children, 2 to 16 years old, with a history of frequent use of emergent health care services for asthma. Intervention. Children in the intervention group received asthma education and medical treatment in the setting of a tertiary care pediatric allergy clinic. An asthma outreach nurse maintained monthly contact with the families enrolled in the intervention group.

OUTCOME MEASURES

Emergency department (ED) visits, hospitalizations, and health care charges per patient in the year after enrollment.

RESULTS

Baseline demographics did not differ significantly between the 2 groups. In the year before the study, there were no significant differences between intervention and control children in ED visits (mean, 3.5 per patient), hospitalizations (mean,.6 per patient) or health care charges ($2969 per patient). During the study year, ED visits decreased to a mean of 1.7 per patient in the intervention group and 2.4 in controls, while hospitalizations decreased to a mean of.2 per patient in the intervention group and.5 in the controls. Average asthma health care charges decreased by $721/child/year in the intervention group and by $178/patient/year in the control group.

CONCLUSIONS

A comprehensive asthma intervention program for Medicaid-insured asthmatic children can significantly improve health outcomes while reducing health care costs.asthma education, health care outcomes, Medicaid, asthma outreach, utilization.

Effects of acute and chronic ethanol exposure on spatial cognitive processing and hippocampal function in the rat

Animals, including rats, have a predisposition to process and use spatial information to organize and guide behavior. The hippocampus and related structures are critically involved in this function, and, consequently, it has been proposed that one function of the hippocampus is to construct "spatial cognitive maps" of environments. Lesions to the hippocampus or its connections produce a pattern of alterations in behavior which include shifts from the use of spatial information to guide behavior to the use of cue- or taxon-based information to guide behavior. Recently it was demonstrated that ethanol interacts with a specific group of neurotransmitter systems, i.e., N-methyl-D-aspartate receptors and GABA(A) receptors that exist in high proportions in the hippocampus and related structures. In this review, we seek to summarize the literature demonstrating that one effect of acute and chronic ethanol exposure is to produce behavioral alterations that are strikingly similar to those found following lesions to the hippocampal system. Furthermore, cellular and anatomical alterations resulting from similar ethanol exposure paradigms will be reviewed and offered as possible mechanisms for producing the alterations in behavior. Finally, several unanswered questions concerning the interaction between ethanol and spatial cognitive processing will be identified.

Chronic blockade of N-methyl-D-aspartate receptors alters gamma-aminobutyric acid type A receptor peptide expression and function in the rat

Chronic in vivo or in vitro application of GABA(A) receptor agonists alters GABA(A) receptor peptide expression and function. Furthermore, chronic in vitro application of N-methyl-D-aspartate (NMDA) agonists and antagonists alters GABA(A) receptor function and mRNA expression. However, it is unknown if chronic in vivo blockade of NMDA receptors alters GABA(A) receptor function and peptide expression in brain. Male Sprague-Dawley rats were chronically administered the noncompetitive NMDA receptor antagonist MK-801 (0.40 mg/kg, twice daily) for 14 days. Chronic blockade of NMDA receptors significantly increased hippocampal GABA(A) receptor alpha4 and gamma2 subunit expression while significantly decreasing hippocampal GABA(A) receptor alpha2 and beta2/3 subunit expression. Hippocampal GABA(A) receptor alpha1 subunit peptide expression was not altered. In contrast, no significant alterations in GABA(A) receptor subunit expression were found in cerebral cortex. Chronic MK-801 administration also significantly decreased GABA(A) receptor-mediated hippocampal Cl- uptake, whereas no change was found in GABA(A) receptor-mediated cerebral cortical Cl- uptake. Finally, chronic MK-801 administration did not alter NMDA receptor NR1, NR2A, or NR2B subunit peptide expression in either the cerebral cortex or the hippocampus. These data demonstrate heterogeneous regulation of GABA(A) receptors by glutamatergic activity in rat hippocampus but not cerebral cortex, suggesting a new mechanism of GABA(A) receptor regulation in brain.

P rats develop physical dependence on alcohol via voluntary drinking: changes in seizure thresholds, anxiety, and patterns of alcohol drinking

BACKGROUND

It has been proposed that the alcohol-preferring P rat meets many of the criteria for an animal model of alcoholism. However, the development of alcohol dependence has not been explored in rats that self-administer ethanol for less than 15-20 weeks. The present study investigated the development of physical dependence upon alcohol after 2-6 weeks of voluntary alcohol intake. Changes in bicuculline-induced seizure thresholds, microstructure of alcohol drinking, and anxiety-related behavior were used as indices of alcohol dependence. In addition, we evaluated the microstructure of alcohol drinking associated with the development of physical dependence upon alcohol.

METHODS

Alcohol (10% ethanol solution) was measured in graduated drinking tubes with both alcohol and water available continuously. Microstructure of alcohol intake was monitored by a computerized drinkometer. Physical dependence upon alcohol was determined by measuring bicuculline-induced seizure thresholds after alcohol withdrawal. Anxiety-related behavior of P rats after alcohol withdrawal was determined by the social interaction and elevated plus maze tests.

RESULTS

Initial alcohol intake in the alcohol-preferring P rat was relatively modest (3.9 +/- 0.4 g/kg/day). Four days of forced alcohol exposure (initiation) followed by 6 weeks of voluntary drinking resulted in an increase of alcohol intake to 5.5 +/- 0.2 g/kg/day. Ethanol self-administration for 6 weeks, but not for 2 or 4 weeks, produced a significant reduction (30%; p < 0.05) in bicuculline-induced seizure thresholds during alcohol withdrawal. Alterations in the microstructure of alcohol intake (i.e., 90% increase in the size of alcohol drinking bouts compared to the baseline [p < 0.001] with no change in bout frequency) were associated with the development of alcohol dependence. Termination of alcohol intake after 6 weeks of voluntary alcohol consumption resulted in increased anxiety according to both the social interaction and elevated plus maze tests.

CONCLUSIONS

The results of this study indicate that 6 weeks of voluntary alcohol intake are sufficient for the development of physical dependence upon alcohol in the alcohol-preferring P rats as measured by susceptibility to bicuculline-induced seizures. This time is much shorter than the 15-20 weeks reported earlier. Development of physical dependence to alcohol was associated with an increase in daily alcohol intake (40% over the baseline), an increase in alcohol intake during each drinking bout (90% over the baseline), and elevated anxiety during alcohol withdrawal.

Neuroactive steroid 3alpha-hydroxy-5alpha-pregnan-20-one modulates electrophysiological and behavioral actions of ethanol

Neuroactive steroids are synthesized de novo in brain, yet their physiological significance remains elusive. We provide biochemical, electrophysiological, and behavioral evidence that several specific actions of alcohol (ethanol) are mediated by the neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP; allopregnanolone). Systemic alcohol administration elevates 3alpha, 5alpha-THP levels in the cerebral cortex to pharmacologically relevant concentrations. The elevation of 3alpha,5alpha-THP is dose- and time-dependent. Furthermore, there is a significant correlation between 3alpha,5alpha-THP levels in cerebral cortex and the hypnotic effect of ethanol. Blockade of de novo biosynthesis of 5alpha-reduced steroids using the 5alpha-reductase inhibitor finasteride prevents several effects of ethanol. Pretreatment with finasteride causes no changes in baseline bicuculline-induced seizure threshold but reverses the anticonvulsant effect of ethanol. Finasteride pretreatment also reverses ethanol inhibition of spontaneous neural activity in medial septal/diagonal band of Broca neurons while having no direct effect on spontaneous firing rates. Thus, elevation of 3alpha,5alpha-THP levels by acute ethanol administration represents a novel mechanism of ethanol action as well as an important modulatory role for neurosteroids in the CNS.

Glycine-gated chloride channels in neutrophils attenuate calcium influx and superoxide production

Recently, it was demonstrated that liver injury and TNF-alpha production as a result of endotoxin (lipopolysaccharide, LPS) were attenuated by feeding animals a diet enriched with glycine. This phenomenon was shown to be a result of, at least in part, activation of a chloride channel in Kupffer cells by glycine, which hyperpolarizes the cell membrane and blunts increases in intracellular calcium concentrations ([Ca(2+)](i)) similar to its action in the neuron. It is well known that hepatotoxicity due to LPS has a neutrophil-mediated component and that activation of neutrophils is dependent on increases in [Ca(2+)](i). Therefore, the purpose of this study was to determine if glycine affected agonist-induced increases in [Ca(2+)](i) in rat neutrophils. The effect of glycine on increases in [Ca(2+)](i) elicited either by the bacterial-derived peptide formyl-methionine-leucine-phenylalanine (FMLP) or LPS was studied in individual neutrophils using Fura-2 and fluorescence microscopy. Both FMLP and LPS caused dose-dependent increases in [Ca(2+)](i), which were maximal at 1 microM FMLP and 100 microgram/ml LPS, respectively. LPS increased intracellular calcium in the presence and absence of extracellular calcium. Glycine blunted increases in [Ca(2+)](i) in a dose-dependent manner with an IC(50) of approximately 0.3 mM, values only slightly higher than plasma levels. Glycine was unable to prevent agonist-induced increases in [Ca(2+)](i) in chloride-free buffer. Moreover, strychnine (1 microM), an antagonist of the glycine-gated chloride channel in the central nervous system, reversed the effects of glycine (1 mM) on FMLP- or LPS-stimulated increases in [Ca(2+)](i). To provide hard evidence for a glycine-gated chloride channel in the neutrophil, the effect of glycine on radioactive chloride uptake was determined. Glycine caused a dose-dependent increase in chloride uptake into neutrophils with an ED(50) of approximately 0.4 mM, an effect also prevented by 1 microM strychnine. Glycine also significantly reduced the production of superoxide anion from FMLP-stimulated neutrophils. Taken together, these data provide clear evidence that neutrophils contain a glycine-gated chloride channel that can attenuate increases in [Ca(2+)](i) and diminish oxidant production by this important leukocyte.

Gender impacts behavioral and neurochemical adaptations in ethanol-dependent rats

Previous investigations have found gender differences in the effects of chronic ethanol exposure on ethanol withdrawal behaviors as well as GABA(A) receptor gene expression. The present investigation extended these studies with additional behavioral and neurochemical measures of ethanol dependence and withdrawal. No significant gender differences in the elevated plus-maze assessment of ethanol withdrawal anxiety behaviors were found. However, the neuroactive steroid, 3alpha,5alpha-THP, increased exploratory behavior in ethanol withdrawn female, but not male, rats. GABA(A) receptor binding assays showed potent competition of [35S]TBPS binding by 3alpha,5alpha-THP. Control females displayed a decreased affinity for 3alpha,5alpha-THP compared to control males, as evidenced by a nearly 30% increase in the IC50 value. There was no significant effect of ethanol withdrawal on 3alpha,5alpha-THP modulation of [35S]TBPS binding. However, gender differences were observed in the effects of chronic ethanol exposure on GABA(A) receptor subunit peptide levels in the hypothalamus. Female rats had a significant increase in peptide levels for the alpha2 and alpha3 but not alpha4 subunit, whereas male rats displayed a significant increase in alpha4 and alpha3 but not alpha2 subunits compared to pair-fed control levels. Chronic ethanol-induced alterations in gene expression in the hypothalamus did not coincide with previous findings in the cerebral cortex. In particular, male rats showed an increase in alpha1 subunit peptide levels in the hypothalamus, whereas significant decreases in this subunit have been observed in the cerebral cortex. Both female and male rats showed significant increases in the alpha3 subunit in the hypothalamus but not the cerebral cortex. Taken together, these studies provide additional support for gender-selective effects of chronic ethanol-elicited adaptations at the molecular level.

The extent of drug therapy for attention deficit-hyperactivity disorder among children in public schools

OBJECTIVES

The purpose of this study was to determine the extent of medication use for attention deficit-hyperactivity disorder (ADHD) in southeastern Virginia.

METHODS

Students enrolled in grades 2 through 5 in school districts in city A (n = 5767 students) and city B (n = 23,967 students) were included. Nurses recorded students who received ADHD medication in school.

RESULTS

The proportion of students receiving ADHD medication was similar in both cities (8% and 10%) and was 2 to 3 times as high as the expected rate of ADHD. Receipt of drug therapy was associated with social and educational characteristics. Medication was used by 3 times as many boys as girls and by twice as many Whites as Blacks. Medication use increased with years in school, and by fifth grade 18% to 20% of White boys were receiving ADHD medication. Being young for one's grade was positively associated with medication use (P < .01). The prevalence of ADHD was 12% in district A, 63% in district B.

CONCLUSIONS

These findings suggest that criteria for diagnosis of ADHD vary substantially across US populations, with potential overdiagnosis and overtreatment of ADHD in some groups of children.

Improving immunization rates in private pediatric practices through physician leadership

OBJECTIVE

To determine whether a physician-led quality improvement initiative can improve immunization rates in participating private practices.

DESIGN

Surveys of private pediatric practices at 6-month intervals over an 18-month period.

SETTING

Ten private pediatric practices in Norfolk and Virginia Beach, Va.

PATIENTS

Children aged 9 to 30 months attending the private practices.

INTERVENTIONS

Practice immunization rates were assessed and presented to practices on 4 occasions at 6-month intervals. A physician leader convened an immunization task force meeting following the first 3 assessments to review practice guidelines, examine data, and discuss practice changes.

MAIN OUTCOME MEASURES

Practice immunization rates for patients at age 24 months, with 3- and 12-month immunization rates as secondary outcomes.

RESULTS

The mean practice immunization rate at age 24 months increased significantly (P<.05) from 50.9% at baseline to 69.7%. Rates also increased at age 3 months, from 75.5% to 88.9%, and at age 12 months, from 72.9% to 84.6%. The median age at administration of the fourth dose of diphtheria toxoid, tetanus toxoid, and pertussis vaccine decreased (P<.05) from 17.6 to 16.8 months. Physicians also reported making additional changes, including improved record keeping and screening for immunizations at every visit.

CONCLUSION

A quality improvement initiative enabling physician leadership can improve preschool immunization practices and coverage levels in pediatric practices.

Fluorescence imaging of GABAA receptor-mediated intracellular [Cl-] in P19-N cells reveals unique pharmacological properties

This study describes the pharmacological properties of GABAA receptors expressed in P19-N cells using fluorescence imaging of intracellular chloride with 6-methoxy-N-ethylquinolinium iodide (MEQ). We show that application of the GABA agonist, muscimol (10-200 microM), produces time- and concentration-dependent increases in intracellular [Cl-] that are blocked by bicuculline. Diazepam (10 microM) and pentobarbital (1 mM) potentiate muscimol-stimulation. These receptors exhibit novel pharmacological properties. The neurosteroid, 3alpha-hydroxy-5alpha-pregnane-20-one (1-10 microM) exhibited weak potency in enhancement of muscimol-stimulation. Ethanol (50 and 100 mM) exhibited high efficacy on muscimol responses, a 4- to 5-fold potentiation, respectively, of muscimol (10 microM) alone. GABA and muscimol allosterically modulated specific binding of [3H]flunitrazepam to differentiated P19 cells. Modulation of GABAA receptor mediated increases in intracellular [Cl-] demonstrated stability in response magnitude from 7 to 15 days following removal of retinoic acid. In concert, GABAA receptor subunit mRNA and protein expression patterns in these neuron-like cells were stable over the same period. Using RT-PCR we determined that differentiated P19 cells lack gamma1, gamma2L, alpha6 and delta subunit mRNAs while expressing alpha1, alpha2, alpha3, alpha4, alpha5, beta1, beta2, beta3, gamma2S and gamma3. Furthermore, subunit specific antibody immunocytochemical labeling of cells with a neuronal morphology indicated the presence of alpha1, alpha2, alpha4, and gamma2 subunits (the only subunits tested). Therefore, P19-N cells should prove useful to researchers in need of a model cell culture system in which to study function and regulation of neuronal GABAA receptors.