Quantification of active caspase 3 in apoptotic cells

We describe an enzyme-linked immunosorbent assay (ELISA) for quantifying relative amounts of active caspase 3 in apoptotic cells. Covalent modification of caspase 3 active sites with a biotinylated inhibitor differentiates active from latent caspases. Capture on an ELISA plate with an antibody specific for caspase 3 makes the assay specific for caspase 3. Detection is with horseradish peroxidase (HRP)-conjugated streptavidin that binds to the biotinylated inhibitor covalently bound to caspase 3. Using the assay we detected 6.6 ng active caspase 3 per 10(6) apoptotic staurosporine-treated Jurkat cells. Specificity of the assay for caspase 3 was demonstrated by lack of signal with purified caspases 2, 7, 8, and 10 that were modified by a biotinylated inhibitor. Specificity was also demonstrated by lack of signal with apoptotic MCF-7 cells which do not express caspase 3. The ability to discriminate between active and latent caspase 3 was shown by Western blotting with HRP-streptavidin and anti-caspase 3. Although latent caspase 3 was captured it was not covalently modified with the biotinylated inhibitor. The basic principle of using a covalent inhibitor to identify active enzymes and an antibody to differentiate between enzymes with similar activities has potential for quantifying active members of many classes of enzymes.

Involvement of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and p53 in neuronal apoptosis: evidence that GAPDH is upregulated by p53

We recently reported that cytosine arabinoside (AraC)-induced apoptosis of cerebellar neurons involves the overexpression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The present study was undertaken to investigate whether p53 and/or Bax overexpression participates in the AraC-induced apoptosis of cerebellar granule cells and, if so, the relationship between p53 induction and GAPDH overexpression in these cells. AraC-induced apoptosis of cerebellar granule cells was preceded by an increase in levels of p53 mRNA and protein detected between 1 and 8 hr after treatment. The mRNA level for a p53 target gene, Bax, was also increased. The increase in GAPDH mRNA lasted longer than that of either p53 or Bax, and the level of GAPDH protein in the particulate fraction increased after induction of GAPDH mRNA. The antisense oligonucleotide to p53 protected granule cells from AraC-induced chromatin condensation, internucleosomal cleavage, and apoptotic death. The inhibition of p53 expression by the p53 antisense oligonucleotide not only blocked the expression of Bax but also partially suppressed the increased GAPDH mRNA and protein levels. Conversely, the suppression of GAPDH expression and subsequent attenuation of apoptosis of granule cells by GAPDH antisense oligonucleotide did not influence the expression of p53 or Bax. Cerebellar granule cells prepared from p53 knock-out mice were resistant to AraC toxicity, and the p53 gene knock-out suppressed AraC-upregulated GAPDH expression. Moreover, infection of PC12 cells with an adenoviral vector containing p53 gene dramatically increased GAPDH expression and triggered cell apoptosis. These results suggest that AraC-induced apoptosis of cerebellar granule cells involves the expression of both GAPDH and p53 and that, similar to Bax, GAPDH is upregulated by p53 after exposure to the apoptotic insult.

Nuclear translocation of glyceraldehyde-3-phosphate dehydrogenase isoforms during neuronal apoptosis

Treatment with cytosine beta-D-arabinoside (AraC; 300 microM) induced a time-dependent accumulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein in nuclei purified from cultured cerebellar granule cells, with a concomitant degradation of lamin B1, a nuclear membrane protein and a substrate of CPP32/caspase-3. Moreover, Asp-Glu-Val-Asp-fluoromethyl ketone (DEVD-fmk), a CPP32-selective antagonist, dose-dependently suppressed AraC-induced apoptosis of these neurons. Nuclear accumulation of GAPDH protein was associated with a progressive decrease in the activity of uracil-DNA glycosylase (UDG), one of the nuclear functions of GAPDH. The nuclear dehydrogenase activity of GAPDH was initially increased after treatment and then decreased parallel to UDG activity. Six GAPDH isoforms were detected in the nuclei of AraC-treated cells. The more alkaline isoforms, 1-3, constituted the bulk of the nuclear GAPDH, and the remaining isoforms, 4-6, were the minor species. Levels of all six isoforms were increased after treatment with AraC for 16 h; a 4-h treatment increased levels of only isoforms 4 and 5. Thus, it appears that various GAPDH isoforms are differentially regulated and may have distinct apoptotic roles. Pretreatment with GAPDH antisense oligonucleotide blocked the nuclear translocation of GAPDH isoforms, and the latter process occurred concurrently with a decrease in cytosolic GAPDH isoforms. Sodium nitroprusside-induced NAD labeling of nuclear GAPDH showed a 60% loss of GAPDH labeling after AraC treatment, suggesting that the active site of GAPDH may be covalently modified, denatured, or improperly folded. The unfolded protein response elicited by denatured GAPDH may contribute to AraC-induced neuronal death.

"You're out of your mind!": Humor as a face-saving strategy during neuropsychological examinations

This article presents a sociolinguistic analysis of humor as a face-saving device in a memory clinic. Data for this article were transcripts of audiotaped clinical examinations between 4 clinicians and 17 patients, conducted at the Memory and Alzheimer's Clinic at the University of California, San Francisco. The study focused on the functions of humor and the complexity involved in examining those functions. Four aspects of humor were examined: (a) who initiates humor, (b) what topics the humor is based on, (c) what the function of the humor is, and (d) who the focus of the humor is. Results indicated that dementia patients initiated a greater number of humor exchanges than did clinicians or third-party observers. In particular, patients initiated a greater number of a specific kind, called dominant humor, with which the initiator controls the interaction. In spite of the power differential between patients and clinicians, dementia patients asserted some dominance over a face-threatening situation. These findings imply the need for further research on nurturing, as well as communicative training of family and caregivers of dementia patients to enhance successful communication and thus successful life experiences for these patients.

Subcellular distribution of glyceraldehyde-3-phosphate dehydrogenase in cerebellar granule cells undergoing cytosine arabinoside-induced apoptosis

We have previously shown that cytosine arabinoside (AraC)-induced apoptosis of cerebellar granule cells (CGCs) results in an increase of a 38-kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12). Antisense oligonucleotides to GAPDH mRNA afford acutely plated CGCs significant protection against AraC-induced apoptosis. We used differential centrifugation to examine which subcellular components are affected. Treated and untreated cells were sonicated in 0.32 M sucrose and sequentially centrifuged at 1,000, 20,000, and 200,000 g, to obtain crude nuclear, mitochondrial, microsomal, and cytosolic fractions. Western blotting showed that the levels of GAPDH protein were markedly increased in the 1,000- and 20,000-g pellets. The levels in the cytosolic supernatant were decreased dramatically by AraC in acutely plated CGCs but not in cells 24 h after plating. It is noteworthy that although GAPDH protein in the pellet fractions increased, the dehydrogenase activity of GAPDH decreased. Two other dehydrogenases, lactate dehydrogenase (EC 1.1.1.27) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49), were not similarly affected, suggesting that the effect was GAPDH specific. These observations suggest that GAPDH levels change in specific organelles during apoptosis for reasons that are separate from its function as a glycolytic enzyme. The accumulation of GAPDH protein in specific subcellular loci may play a role in neuronal apoptosis.

Antagonists have a greater selectivity for muscarinic receptor subtypes in intact cerebellar granule cells than in membranes

A comparison of muscarinic acetylcholine receptor (mAChR) antagonist binding properties was made between intact cerebellar granule cell cultures and membranes prepared from these cells. [3H]quinuclidinyl benzylate (QNB) binding displacement by four mAChR antagonists was measured and the selectivities for m2- or m3-mAChRs estimated by curve fitting. For each antagonist, the preparation of membranes caused a subtype selective decrease in receptor affinity, as compared to intact cell binding. The m2-selective antagonists had lower affinities in membranes for m2- but not for m3-mAChR, while the m3-selective antagonists had lower affinities for m3- but not for m2-mAChR. As a result, the m2-mAChR selectivity of AF-DX 116 and methoctramine in membranes was 66- and 1.7-fold less than in intact cells, and the m3-mAChR selectivity of 4-DAMP and pFHHSiD was 2.4- and 3.9-fold less in membranes than in intact cells. The m3-mAChR selectivity of 4-DAMP in intact cells was unaffected by cytoskeletal depolymerization with cytochalasins and colchicine. We suggest that the changes in selectivity seen with cell disruption may be due to a loss of cellular factors which regulate receptor properties. Antagonists binding to receptors on intact cells may cause subtype-specific changes in the interaction of the mAChR with these factors. These data suggest that mAChR antagonist binding selectivity needs to be re-examined in intact cell systems.

A pilot study of a computerized assessment (AGE-PC) for the elderly in general practice

A pilot project was undertaken in Liverpool UK, to investigate whether data useful for both general practice and public health purposes could be collected by primary care personnel using a computerized semi-structured interview (AGE-PC) for assessment of patients aged 75 and over. A high degree of variation between practices was found in the proportion of elderly assessed with AGE-PC largely related to motivation to undertake assessments and methods employed to approach patients. Considerable differences between and within practices were evident in staff attitudes to the need for detailed formal assessments and the use of computers. Several aspects of the AGE-PC package itself were identified as requiring modification including streamlining data transfer methods, adding facilities for analysis and giving users a degree of choice over content of the assessment. This technique does offer a potentially efficient means of collecting very detailed standardized data for intra- or inter-practice analysis while at the same time generating a comprehensive report for individual patients. However, in the context of the over-75 assessments it was too time-consuming. Possible future strategies are discussed such as using an initial screening stage with a self-report questionnaire to reduce numbers needing full assessment and the use of the package for the community care assessments. The pilot project highlighted some of the potential advantages and disadvantages of collecting data from primary health care for public health purposes.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood pressure as a risk factor for depression in elderly people: a prospective study

A total of 1070 men and women aged 65 years and over living in the community in Liverpool were interviewed using the Geriatric Mental State. Diagnoses of depression at case and subcase level were made using the GMS-AGECAT package from an initial interview and at follow-up three years later. Data relating to blood pressure at year 0 was available on 748 subjects. Men not taking anti-hypertensives or antidepressants with diastolic blood pressure greater than 85 mmHg were significantly less likely to be subcases than men with low or normal diastolic pressure. People in this group were also significantly less likely to be cases 3 years later. There were no other significant findings. These results do not support an association between low blood pressure and coincidental or future subcase- or case-level depressive illness.

Interactions of ginsenosides with ligand-bindings of GABA(A) and GABA(B) receptors

1. Total saponin fraction decreased the affinity of specific [3H]muscimol binding without changes in Bmax. Ginsenoside Rb1 Rb2, Rc, Re, Rf and Rg1 inhibited the specific [3H]muscimol binding to the high-affinity site. 2. Total saponin fraction increased the affinity of specific [3H]flunitrazepam binding. Ginsenoside Re and Rf enhanced specific [3H]flunitrazepam binding. 3. Total saponin fraction decreased the affinity of specific [35S]TBPS binding without changes in Bmax. Ginsenosides did not affect specific or non-specific [35S]TBPS binding. 4. Total saponin fraction decreased the affinity of specific [3H]baclofen binding without changes in Bmax. Ginsenoside Rc inhibited specific [3H]baclofen binding.

Binding characteristics of [3H]flunitrazepam in pentobarbital-withdrawal rats

The effects of chronic pentobarbital (PB) treatment on the binding characteristics of [3H]flunitrazepam (FLU) in rat brain were examined. Saline or sodium PB (500 micrograms/10 microliters/hr) was infused into the lateral cerebral ventricles of rats for 6 days using osmotic pumps. Immediately before withdrawal, there were no significant differences in [3H]FLU binding constants (KD and Bmax) between saline and PB groups. However, 24 hr withdrawal caused an increase in Bmax with no changes in KD. The enhancement of [3H]FLU binding by in vitro addition of chloride ions and PB was not affected after the PB infusion. The PB enhancement of [3H]FLU binding was inhibited by the convulsant, picrotoxinin. PB withdrawal did not cause significant differences in the binding constants of [3H]Ro 15-1788, a benzodiazepine (BZ) antagonist, between the saline and PB groups. Pretreatment of membranes with 0.02 mM of 3-[(3-cholamidopropyl)-dimethylammonio]-1- propanesulfonate (CHAPS), a zwitterionic detergent, caused decreases in both KD and Bmax in FLU binding in PB-withdrawal membrane, but not in the saline-treated membrane. The enhancement of [3H]FLU binding by chloride ions and PB was not affected by the CHAPS treatment. These results suggest that the change in BZ receptors induced by PB withdrawal is functionally linked to the GABA-BZ-barbiturate receptor complex and that PB withdrawal induces some conformational changes in BZ receptors.

Ontogeny of GABAA receptor subunit mRNAs in rat spinal cord and dorsal root ganglia

Relatively little is known about the development of GABAA receptor subunits and their gene expression in mammalian spinal cord. The expression of mRNAs encoding 13 GABAA receptor subunits (alpha 1-6, beta 1-3, gamma 1-3, and delta) in embryonic, postnatal, and adult rat spinal cord and dorsal root ganglia (DRG) cells were studied by in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Both techniques revealed the presence of all subunit mRNAs originally found in the rat brain, except for alpha 6, which was not detectable, and delta, which was weakly detected only by RT-PCR. Two anatomically distinctive sets of subunit mRNAs were found by in situ hybridization within the ventricular zone (VZ) and mantle zone (MZ). The trio of alpha 4, beta 1, and gamma 1 subunit mRNAs emerged exclusively in neuroepithelial cells at embryonic day 13 (E13) and remained detectable in the VZ until E17. In the MZ, beta 3 subunit mRNA was first detected at E12, while alpha 2, alpha 3, alpha 5, beta 2, gamma 2, and gamma 3 transcripts appeared at E13. Expressions of the subunit mRNAs in the MZ rapidly increased and expanded in a ventrodorsal sequence from motoneurons to dorsal horn neurons before reaching a peak in the late embryonic/early postnatal period. The mRNA expressions declined during postnatal development, by region-selective depletion, with alpha 4, alpha 5, beta 1, beta 2, gamma 1, and gamma 3 subunit mRNAs becoming barely detectable. In contrast, alpha 2, alpha 3, beta 3, and gamma 2 transcripts persisted into adulthood with distinct anatomical distributions. RT-PCR analysis revealed unique developmental patterns in the intensities of PCR products, most of which were in good agreement with developmental changes in the densities of hybridized mRNA signals. However, RT-PCR amplified minute amounts of mRNAs for alpha 1, alpha 4, alpha 5, beta 1, beta 2, gamma 1, gamma 3, and delta subunits in adults, which were not found in film autoradiograms, but could be detected in a few grain-positive cells in emulsion-dipped sections. DRG cells expressed alpha 2, alpha 3, alpha 5, beta 2, beta 3, and gamma 2 subunit mRNAs during embryogenesis but only alpha 2, beta 3, and gamma 2 subunit mRNAs were reliably detected in the adult.(ABSTRACT TRUNCATED AT 400 WORDS)

Agonist-induced down-regulation and antagonist-induced up-regulation of m2- and m3-muscarinic acetylcholine receptor mRNA and protein in cultured cerebellar granule cells

Cerebellar granule cells express m2- and m3-muscarinic acetylcholine receptors (mAChRs) and their corresponding mRNA with m3-mAChR being the predominant receptor subtype. After stimulation with the mAChR agonist, carbachol, m2- and m3-mAChR mRNA levels were decreased in a time- and concentration-dependent manner with the maximal down-regulation at 2 and 8 hr, respectively. Immunoprecipitation studies revealed that amounts of m2- and m3-mAChR protein also decreased at 8 and 24 hr, respectively. The carbachol-induced down-regulation of m3-mAChR mRNA was associated with a decrease in the transcription rate, but a substantial enhancement of the mRNA stability. Upon removal of carbachol after treatment for 8 hr, the levels of m3-mAChR mRNA and mAChR binding sites returned to their original values with a t1/2 of approximately 80 min and 6 hr, respectively. The carbachol-elicited loss of m2- and m3-mAChR mRNA was blocked by their corresponding receptor subtype-specific antagonists, AF-DX 116 (m2-selective) and 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) (m3-selective), and was concurrent with an increase in c-fos mRNA levels. Exposure of granule cells to the nonselective mAChR antagonist, atropine, caused a time- and concentration-dependent increase in the level of both m2- and m3-mAChR mRNA and mAChR binding sites. At 24 hr, immunoprecipitable m3-mAChR protein was predominantly increased. The atropine-induced up-regulation of m3-mAChR mRNA was concurrent with a marked enhancement of the mRNA stability and its transcription rate. The elevated levels of m3-mAChR mRNA and binding sites declined to their untreated values after the removal of atropine. Treatment with AF-DX 116 and 4-DAMP also produced an increase in the level of m2- and m3-mAChR mRNA and their corresponding immunoprecipitable receptor protein. These results demonstrate that the mAChR agonist and antagonist induce a down- and up-regulation of mAChR expression, respectively, through receptor-mediated mechanisms in cerebellar granule cells. Moreover, at least for m3-mAChR mRNA, the agonist- and antagonist-induced effects are reversible and associated with corresponding changes in the transcription rate of this receptor mRNA species.

The prevalence of dementia, depression and neurosis in later life: the Liverpool MRC-ALPHA Study

Prevalence rates for psychiatric disorders in the elderly are presented from the initial cross-sectional stage of a longitudinal community study of the incidence of dementia in the city of Liverpool. Together with five other centres in the UK the MRC-ALPHA project forms part of the MRC multicentre incidence study of dementia and cognitive decline. An age- and sex-stratified random sample of 5222 subjects aged > or = 65 was interviewed at home using the Geriatric Mental State-AGECAT package to provide computer diagnoses. The overall age-standardized prevalence rates for organic disorder (4.7%) depressive illness (10.0%) and the neuroses (2.5%) are consistent with levels found in previous smaller studies that have used GMS-AGECAT. Each of these diagnoses is more common in females than males. A rise in organic disorder with age is confirmed as continuing into the oldest age groups for both sexes. An apparent decline with age observed for depression and neurosis diagnoses disappears when organic cases are excluded from the analysis.

Induction of tolerance to and physical dependence on pentobarbital continuous intracerebroventricular administration

A new model of barbiturate tolerance and dependence was developed using i.c.v. infusion of pentobarbital. Male Harlan Sprague-Dawley rats weighing 250 to 300 were implanted with i.c.v. cannulae and infused with sodium pentobarbital (500 micrograms/10 microliters/hour) for 6 days. The pentobarbital-infused group had a shorter duration of pentobarbital-induced loss of righting reflex than the saline-infused group. When i.c.v. pentobarbital- and saline-infused rats were injected with sodium pentobarbital (60 mg/kg i.p.), the time course of pentobarbital levels in the serum and in the brain were not significantly different. The infusion of pentobarbital also did not induce hepatic drug-metabolizing enzymes. The depth of thiopental-induced hypothermia was decreased by i.c.v. pentobarbital infusion. During the course of the infusion, the basal body temperature of the pentobarbital-infused rats did not change. Two days after the infusion was discontinued, the basal body temperature was elevated. The increase in body temperature lasted for 8 days. Twenty-four hours after the infusion was discontinued, the pentobarbital-infused rats had a significantly shorter onset of t-butylbicyclophosphorothionate (TBPS)-induced convulsions. These studies show that i.c.v. infusion can be used to induce pentobarbital tolerance and dependence. This model has the advantage that issues related to induction of hepatic drug-metabolizing enzymes are eliminated, and it may be useful in the study of barbiturate addiction.

Prospective data on the prevalence of abnormal involuntary movements among elderly people living in the community

Trained raters from the Liverpool Continuing Health in the Community study interviewed 1070 people over the age of 65 in 1982-1983 using the Geriatric Mental State (GMS) examination. Three years later the cohort was re-interviewed, this time by psychiatrists trained in the GMS, who used the GMS and the History and Aetiology Schedule (HAS). The cohort had fallen in size to 875, because of mortality; 701 were re-interviewed. The cohort was followed up again 6 years after the first interview by trained nurse raters using the GMS (A3) and the Mini-Mental State Examination. Cases of mental disorder identified by the computer diagnostic program AGECAT were re-interviewed by psychiatrists along with a number of controls using the GMS and the HAS on the remaining 450 individuals. Observational behavioural ratings from the GMS and summary sheets were analysed along with AGECAT diagnoses and data on medication gained at the 3 assessments. The community prevalence of tardive dyskinesia and other movement disorders in elderly people over a 6-year follow-up appears to be very low (the community prevalence of tardive dyskinesia being 0.22% and akathisia 1.57%), is usually associated with organic mental disorder (and consequently higher mortality) and is furthermore not usually associated with antipsychotic medication.

Risk factors for depression in elderly people: a prospective study

In 1982-1983 a random sample of 1486 people aged 65 years and above was generated from general practitioner lists; 1070 were interviewed in the community using the Geriatric Mental State and a Social History questionnaire. The cohort was followed up by interview 3 years later. At year 3 the diagnostic computer program AGECAT diagnosed 44 incident cases of depression. Information from the depressed group's initial and further interviews was compared with a control group (which excluded cases of affective or organic mental illness). Univariate analysis yielded three factors that were significantly associated with the development of depression 3 years later: a lack of satisfaction with life; feelings of loneliness; and smoking. Multivariate analysis confirmed their independent effects and revealed 2 further factors attaining significance: female gender and a trigger factor, bereavement of a close figure within 6 months of the third-year diagnosis. Some other factors traditionally associated with depression, such as poor housing, marital status and living alone, failed to attain significance as risk factors.

Alzheimer's disease, other dementias, depression and pseudodementia: prevalence, incidence and three-year outcome in Liverpool

A group of 1070 community-living persons aged 65 and over was assessed using the GMS-AGECAT package and other interviews at years 0 and 3. Year 3 interviewers were 'blind' to the findings at year 0, and the prevalence of organic disorders and depression was very similar in both years. According to the results at year 3, minimum and maximum prevalence figures for dementia at year 0 were 2.4% and 3.8% for moderate to severe and 0.4% and 2.4% for mild or early cases, with a best estimate of 3.5% and 0.8%, or 4.3% overall, divided into: senile, Alzheimer's type 3.3%; vascular 0.7%; and alcohol-related 0.3%. The overall incidence of dementia, clinically confirmed by six-year follow-up, was 9.2/1000 per year (Alzheimer type 6.3, vascular 1.9, alcohol related 1.0). Three years later, 72.0% of those with depressive psychosis and 62.3% of those with depressive neurosis were either dead or had some kind of psychiatric illness. Nearly 60% of milder depressive cases (7.2% of the total sample) had either died or developed a chronic mental illness. The outcome of depressive pseudodementias is equivocal so far. Findings at year 3 provide validation of AGECAT computer diagnosis against outcome; organic and depression diagnoses are seen to have important implications for prognosis.

The natural history of neurotic disorder in an elderly urban population. Findings from the Liverpool longitudinal study of continuing health in the community

A random community sample of 1070 subjects aged 65 years and over was interviewed at home using the GMS-AGECAT package and followed up three years later. Neurotic symptoms were common, but symptoms sufficient to reach 'case' level were much less frequent. The overall prevalence of neurotic 'cases' was 2.4% in year 0 and 1.4% in year 3. The incidence was estimated as a minimum of 4.4 per 1000 per year over the age of 65. Women were more likely to be 'cases' than men but not 'subcases', and there was a general decline in prevalence with increasing age, particularly for 'subcases'. Anxiety was the commonest neurotic subtype. After three years, 'cases' were shown not to persist, but this did not reflect wellness. There was a tendency still to have some symptoms, but the predominant symptom appeared to change, suggesting a possible chronic neurotic disorder with changing presentation over time. Depressive symptoms were closely associated with this presentation, suggesting that depression may be an important and integral part of a general, changing neurotic disorder.

Geriatric Mental State-AGECAT: prevalence, incidence and long-term outcome of dementia and organic disorders in the Liverpool study of continuing health in the community

The GMS-AGECAT package was used in the initial assessment and 3-year follow-up of a random sample of 1,070 elderly people living in the community. A prevalence of 4.3% is found for dementia after confirmation of diagnoses by outcome at year 3. The overall incidence of dementia was 9.2/1,000 per year after partial adjustments for outcome of year 6. Incidence per year for sub-types of dementia were AD 6.3/1,000, vascular 1.9/1,000, and alcohol-related 1.0/1,000.

Alpha: the Liverpool MRC Study of the incidence of dementia and cognitive decline

The design and methods of this longitudinal study of dementia which is underway are described. An age- and sex-stratified random sample of 6,000 elderly community subjects are being re-assessed after a 2-year interval using the GMS-AGECAT package. Alpha forms part of the MRC funded UK multicentre incidence study and an international network of collaborative studies using comparable measures.

Effects of pentobarbital tolerance and dependence on convulsant and GABAA receptor antagonist binding

Experiments were performed which examined the effects of pentobarbital tolerance and dependence on GABAA receptor antagonist binding. In rats implanted with pentobarbital pellets for 7 days, followed by 24 hours of withdrawal, there was a significant decrease in the latency of TBPS-induced seizures and an increase in [35S]TBPS binding in the frontal cortex. The pentobarbital tolerant rats had a significant increase in the low affinity KD of [3H]SR95531 binding. Removal of the pellets for 24 hours caused a reversal of the effect on the low affinity KD and caused a decrease in the number of low affinity binding sites. In vitro addition of pentobarbital to binding assays produced a decrease in the number of high affinity [3H]SR95531 binding sites without changing low affinity binding. In the cerebellum, the binding in none of the treatment groups was significantly different from placebo. These observations suggest that pentobarbital tolerance and withdrawal cause changes in the properties of the GABAA receptor antagonist binding site which are different from those caused by in vitro exposure to the drug.

Effects of pentobarbital tolerance to and dependence on GABAB receptor-binding

Effects of pentobarbital pellet implantation on [3H]baclofen binding in the frontal cortex of cerebellum of rat brains were examined. In the frontal cortex, pentobarbital tolerance caused an increase in the number of binding sites (Bmax) without changing their affinity (KD). Twenty-four hours after withdrawal of the pentobarbital pellets, there was a significant increase in the KD and Bmax values. Cerebellar binding, in contrast, was not significantly changed in any of the treatment groups. Addition of 1 mM of pentobarbital directly to binding assays using cortical membrane produced as increase in KD without a change in Bmax. In vitro, pentobarbital affected neither the KD nor the Bmax in the cerebellar [3H]baclofen binding. These results suggest that like the GABAA receptor, [3H]baclofen binding to the GABAB receptor in rat frontal cortex was affected by pentobarbital tolerance and dependence, and that there are regional differences in the properties of the GABAB receptor.

Heavy drinking as a risk factor for depression and dementia in elderly men. Findings from the Liverpool longitudinal community study

A random community sample of subjects aged 65 and over was re-interviewed after three years by psychiatrists using the GMS and HAS. The relationship between drinking history and current psychiatric morbidity was examined. Men with a history of heavy drinking for five years or more at some time in their lives were found to have a greater than fivefold risk of suffering from a psychiatric disorder at the time of the interview. Among this group past alcohol consumption was significantly higher for those with a current psychiatric diagnosis compared with those who were well. This association between heavy alcohol consumption in earlier years and psychiatric morbidity in later life is not explained by current drinking habits.

Pentobarbital tolerance and withdrawal: correlation with effects on the GABAA receptor

A model for the development of pentobarbital tolerance and dependence was characterized and correlated with changes in radioligand binding to the GABAA-benzodiazepine receptor chloride channel complex. While one day of pentobarbital exposure decreased the duration of loss of righting reflex, tolerance to the hypothermic effects of thiopental and barbital took 7 days to develop, indicating that pharmacokinetic and pharmacodynamic tolerance are separable. Increased sensitivity to pentylenetetrazol-induced seizures was first observed after 3 days of pentobarbital exposure, suggesting brain areas involved in seizure control develop tolerance to, and dependence on pentobarbital faster than those involved in temperature regulation. Acute exposure to pentobarbital in vivo did not affect cortical binding of [3H]muscimol in vitro, while tolerance caused a decrease in binding due to an increase in the low-affinity site KD. Pentobarbital tolerance also caused a decrease in the cortical binding of the benzodiazepine, [3H]flunitrazepam. These observations suggest that the acute effects of barbiturates on the GABAA receptor complex are reversible, while tolerance causes receptor modifications which may be related to the development of physical dependence.

Barbiturates and the GABAA receptor complex

The GABA synapse plays an important role in the pharmacologic effects of barbiturates and the mechanisms involved in barbiturate tolerance and dependence. A synopsis of the effects which have been reported to date is found in Tables 1 and 2. Although the acute changes in neurotransmitter uptake and release are nonselective, a lag in the ability of the GABA synapse to compensate for discontinuation of barbiturate exposure may be important in the symptoms of withdrawal. Barbiturates cause changes in the properties of many receptors, but manipulations of the GABAA receptor in vivo correlate with changes in the therapeutic and toxicologic responses to barbiturates, indicating that the GABAA receptor complex plays a pivotal role in the effects of barbiturates. Experiments done in several laboratories show that barbiturate tolerance and dependence cause subtle changes in the properties of the GABAA receptor complex. These observations suggest that decreased GABA-stimulated chloride channel activity and reduced ability to modulate it may be important in causing barbiturate tolerance and the symptoms observed in withdrawal. Selection of drug-resistant rodent strains suggests that there may be genetic factors involved in drug tolerance and dependence. The complexity of the responses of the GABA synapse to both acute and prolonged exposure to barbiturates indicates that it is a valuable model for understanding how the central nervous system responds to drugs and the mechanisms involved in drug addiction.

Binding characteristics of t-[35S]butylbicyclophosphorothionate in discrete brain regions of rats made tolerant to and dependent on pentobarbital

The effects of acute and continuous pentobarbital administration by pellet implantation on binding characteristics of t-[35S]butylbicyclophosphorothionate ([35S]TBPS) in discrete regions of rat brains were examined. Acute administration of pentobarbital (60 mg/kg, s.c.) affected neither the KD nor the Bmax values of [35S]TBPS binding in any of the regions studied. The cerebella of pentobarbital-tolerant rats had an increased density of [35S]TBPS binding sites with no change in their apparent affinity. There were no significant changes in the binding characteristics in the frontal cortex (FC), the striatum (ST), and the substantia nigra (SN) of these animals. Twenty-four hours after removal of the pentobarbital pellets, a significant decrease in the latency of onset of first twitch response induced by pentylenetetrazol (PTZ) (50 mg/kg, i.p.) was observed. In addition, the density of [35S]TBPS binding sites was significantly increased in the FC, the SN, and the cerebellum but not in the ST. In all brain regions studied, placebo pellet implantation and pentobarbital tolerance and dependence caused no changes in the apparent affinity of [35S]TBPS binding or the IC50 of pentobarbital for the inhibition of [35S]TBPS binding. These results suggest that [35S]TBPS binding was significantly increased following the withdrawal of the pentobarbital pellets without altering intrinsic coupling activity of barbiturate recognition sites and convulsant binding sites and that these increases in [35S]TBPS binding are related to the increased susceptibility to seizures induced by PTZ in rats made dependent on pentobarbital.