Platelet Adenylyl Cyclase Activity Research Articles

Commentary on: Predictive value of health-related quality of life in progression of disability and depression in persons with multiple sclerosis: a 3-year study

Tepavcevic et al. [1] have provided interesting data in their recent article. Interestingly, a number of new biomarkers may help in detection and assessment of depression. One emerging marker is platelet GSK3B activity. Patients with severe depression tend to demonstrate higher GSK3B activity [2]. Similarly, patients with co-existing impairment of cognition secondary to depression demonstrate higher GSK3B activity. Assessment of platelet adenylyl cyclase activity is another way to diagnose depression. In general, altered platelet adenylyl cyclase activity is observed in patients with more severe degree of depression [3]. Another emerging marker is interleukin-18. It is especially sensitive in detecting post-stroke depression. Serum interleukin-18 is usually measured a week after the stroke [4]. Interestingly, the risk of depression even half a year after the stroke can be predicted by assessing serum interleukin-18 levels. Beta-arrestin signaling complex is another emerging biomarker of depression [5]. Assessment of thyroid peroxidase antibody level is another way to assess for possible depression. This is an especially sensitive test to predict the chances of postpartum depression [6]. Similarly, elevated copper levels are seen in patients with depression making it a possible biomarker. Levels as high as 21 % above normal have been seen in depression patients [7]. Similarly, assessment of serum zinc levels helps in detecting treatment resistance in patients with depression [8]. The above examples briefly highlight the emerging new biomarkers of depression. Hopefully, the coming few years will see increased application of these markers.

Antidepressant-like behavioral and neurochemical effects of the citrus-associated chemical apigenin

Apigenin is one type of bioflavonoid widely found in citrus fruits, which possesses a variety of pharmacological actions on the central nervous system. A previous study showed that acute intraperitoneal administration of apigenin had antidepressant-like effects in the forced swimming test (FST) in ddY mice. To better understand its pharmacological activity, we investigated the behavioral effects of chronic oral apigenin treatment in the FST in male ICR mice and male Wistar rats exposed to chronic mild stress (CMS). The effects of apigenin on central monoaminergic neurotransmitter systems, the hypothalamic–pituitary–adrenal (HPA) axis and platelet adenylyl cyclase activity were simultaneously examined in the CMS rats. Apigenin reduced immobility time in the mouse FST and reversed CMS-induced decrease in sucrose intake of rats. Apigenin also attenuated CMS-induced alterations in serotonin (5-HT), its metabolite 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA) levels and 5-HIAA/5-HT ratio in distinct rat brain regions. Moreover, apigenin reversed CMS-induced elevation in serum corticosterone concentrations and reduction in platelet adenylyl cyclase activity in rats. These results suggest that the antidepressant-like actions of oral apigenin treatment could be related to a combination of multiple biochemical effects, and might help to elucidate its mechanisms of action that are involved in normalization of stress-induced changes in brain monoamine levels, the HPA axis, and the platelet adenylyl cyclase activity.

Antidepressant-like effects of the mixture of honokiol and magnolol from the barks of Magnolia officinalis in stressed rodents

Honokiol and magnolol are the main constituents simultaneously identified in the barks of Magnolia officinalis, which have been used in traditional Chinese medicine to treat a variety of mental disorders including depression. In the present study, we reported on the antidepressant-like effects of oral administration of the mixture of honokiol and magnolol in well-validated models of depression in rodents: forced swimming test (FST), tail suspension test (TST) and chronic mild stress (CMS) model. The mixture of honokiol and magnolol significantly decreased immobility time in the mouse FST and TST, and reversed CMS-induced reduction in sucrose consumption to prevent anhedonia in rats. However, this mixture was unable to affect ambulatory or rearing behavior in the mouse open-field test. CMS induced alterations in 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) levels in various brain regions of rats. An increase in serum corticosterone concentrations and a reduction in platelet adenylyl cyclase (AC) activity were simultaneously found in the CMS rats. The mixture of honokiol and magnolol at 20 and 40 mg/kg significantly attenuated CMS-induced decreases of 5-HT levels in frontal cortex, hippocampus, striatum, hypothalamus and nucleus accumbens. And it markedly increased 5-HIAA levels in frontal cortex, striatum and nucleus accumbens at 40 mg/kg and in frontal cortex at 20 mg/kg in the CMS rats. A subsequent reduction in 5-HIAA/5-HT ratio was found in hippocampus and nucleus accumbens in the CMS rats receiving this mixture. Furthermore, the mixture of honokiol and magnolol reduced elevated corticosterone concentrations in serum to normalize the hypothalamic–pituitary–adrenal (HPA) hyperactivity in the CMS rats. It also reversed CMS-induced reduction in platelet AC activity, via upregulating the cyclic adenosine monophosphate (cAMP) pathway. These results suggested that the mixture of honokiol and magnolol possessed potent antidepressant-like properties in behaviors involved in normalization of biochemical abnormalities in brain 5-HT and 5-HIAA, serum corticosterone levels and platelet AC activity in the CMS rats. Our findings could provide a basis for examining directly the interaction of the serotonergic system, the HPA axis and AC-cAMP pathway underlying the link between depression and treatment with the mixture of honokiol and magnolol.

A Sex-Specific Role of Type VII Adenylyl Cyclase in Depression

Major depression represents a complex mental disorder. The identification of biological markers that define subtypes of major depressive disorder would greatly facilitate appropriate medical treatments, as well as provide insight into etiology. Reduced activity of the cAMP signaling system has been implicated in the etiology of major depression. Previous work has shown low adenylyl cyclase activity in platelets and postmortem brain tissue of depressed individuals. Here, we investigate the role of the brain type VII isoform of adenylyl cyclase (AC7) in the manifestation of depressive symptoms in genetically modified animals, using a combination of in vivo behavioral experiments, gene expression profiling, and bioinformatics. We also completed studies with humans on the association of polymorphisms in the AC7 gene with major depressive illness (unipolar depression) based on Diagnostic and Statistical Manual of Mental Disorders IV criteria. Collectively, our results demonstrate a sex-specific influence of the AC7 gene on a heritable form of depressive illness.

Agonist and Antagonist Effects of 15R-Prostaglandin (PG) D2and 11-Methylene-PGD2on Human Eosinophils and Basophils

Prostaglandin (PG) D2 acts through both the DP(1) receptor, which is coupled to adenylyl cyclase, and the DP2 receptor (chemoattractant receptor-homologous molecule expressed on Th2 cells), which is present on eosinophils, basophils, and Th2 cells and results in cell activation and migration. The most potent prostanoid DP2 agonist so far reported is 15R-methyl-PGD2, in which the hydroxyl group has the unnatural R configuration. In contrast, the corresponding analog possessing the natural 15S configuration is approximately 75 times less potent. This raised the question of whether the isoprostane 15R-PGD2 might have potent DP2 receptor-mediated biological activity. We therefore chemically synthesized 15R-PGD2 and investigated its biological activity. This compound elicited DP2 receptor-mediated CD11b expression in human basophils and eosinophils and induced actin polymerization and migration in eosinophils with a potency about the same as that of PGD2. In contrast, it had only a weak effect on DP1 receptor-mediated adenylyl cyclase activity in human platelets. We also investigated the effects of modification of the 9-hydroxyl and 11-oxo groups of PGD2. Both PGK2, in which the 9-hydroxyl group is replaced by an oxo group, and 11-deoxy-11-methylene PGD2, in which the 11-oxo group is replaced by a CH2 group, have little or no DP1 or DP2 agonist activity. However, the 11-methylene analog is a DP2 antagonist (IC50, approximately 2 microM). We conclude that 15R-PGD2, which may be generated by oxidative stress, is a potent and selective DP2 agonist and that modification of the 11-oxo group of PGD2 can result in DP2 antagonist activity.

Platelet Adenylyl Cyclase Activity: A Biological Marker for Major Depression and Recent Drug Use

Adenylyl cyclase (AC) is an enzyme that can regulate the physiologic effects of numerous drugs and hormones through the production of cyclic adenosine-3',5'-monophosphate (cAMP). Some studies suggest that certain measures of AC activity are lower among depressed subjects. We examined the relationship between various measures of AC activity and major depression, taking into account potential confounders, such as drug use and gender. We assessed the relationship between platelet levels of AC activity and lifetime diagnosis of major depression among 1481 participants (226 subjects with a history of major depression and 1255 control subjects) in an international, cross-sectional study initiated by the World Health Organization and the International Society on Biomedical Research on Alcoholism. After accounting for recent drug use, subjects with a history of major depression had markedly lower mean levels for all measures of platelet AC activity compared with control subjects. The adjusted odds ratios for major depression comparing the bottom to the top quartile of AC activity were 2.69 for basal (95% confidence interval [CI] 1.30-5.56), 3.72 for cesium fluoride-stimulated (95% CI 1.54-8.98), 6.20 for forskolin-stimulated (95% CI 2.04-18.80), and 2.20 for Gpp(NH)p-stimulated (95% CI 1.03-4.70). Subjects with major depression have lower platelet AC activity levels, and this relationship is dramatically attenuated by various types of drug use.

Molecular and biochemical evidence for the presence of Type III adenylyl cyclase in human platelets

The isoform(s) of adenylyl cyclase (AC) present in human platelets has not been identified, and evidence supporting a role for AC in platelet aggregation is equivocal. We recently characterized deaggregation as an active component of the platelet aggregation response that may be an important determinant of the extent and duration of aggregation. G i -coupled receptors are linked to the inhibition of AC and are targets of antiplatelet drugs. They also affect platelet aggregation by modulating deaggregation, suggesting a role for AC in modulating this response. The purpose of this study was to identify the AC isoform(s) present in human platelets and to identify its physiological modulators. RT-PCR screening of platelet, buffy coat layer cell and bone marrow megakaryocyte cDNA, and Western blot analysis with AC type III (AC-III) antibodies identified AC-III in platelets and in megakaryocytes. Human platelet AC-III was cloned and expressed in HEK293 cells and its characteristics compared to native platelet AC. Both platelet AC and cloned AC-III required Mg 2+ for activity, were insensitive to Ca 2+ and were G s - and G i -coupled. Zn 2+ and SQ22536 inhibited platelet AC activity. The affinity of SQ22536 was increased with Mg 2+ -related stimulation of AC, while that of Zn 2+ was unchanged, which is consistent with a non-competitive interaction between the two metal ions on AC. The Zn 2+ chelator TPEN reversed the inhibitory effects of Zn 2+ . This study identified AC-III as the predominant AC isoform in human platelets, the activity of which may affect the extent and duration of the net aggregation response by modulating deaggregation.

Platelet Adenylyl Cyclase Activity as a State or Trait Marker in Alcohol Dependence: Results of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence

Background There has been considerable interest in identifying biochemical markers indicative of a genetic predisposition to alcohol dependence (“trait markers”), as well as biochemical markers of recent alcohol drinking (“state markers”). Platelet adenylyl cyclase activity has been suggested as a trait and/or as a state marker related to alcohol dependence. We have now measured platelet adenylyl cyclase activity in more than 1400 well-characterized subjects, which allows us to investigate the influence of a broad range of factors on this activity. Methods Subjects were recruited as part of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence and were interviewed by using the WHO/ISBRA Interview Schedule. Adenylyl cyclase activity (basal, cesium fluoride [CsF]-, forskolin- and Gpp(NH)p-stimulated activities) was measured in platelet samples that were obtained at the time of interview. Data were analyzed by multivariate regression analyses. Results The multivariate analyses revealed that recent abstinence from alcohol was associated with diminutions in platelet adenylyl cyclase activities. A positive family history of alcohol dependence was associated with higher levels of adenylyl cyclase activities, and there was a significant interaction between the effect of alcohol consumption in the past month and family history of alcohol dependence; that is, the influence of alcohol consumption depended on whether the individual had a positive family history. A history of marijuana abuse also was associated with higher levels of platelet adenylyl cyclase activities, and a history of major depression was associated with lower levels of forskolin- and CsF-stimulated activities. Sex, race, and site of recruitment also affected some adenylyl cyclase activities, but there was no significant association of alcohol dependence or abuse with any of the platelet adenylyl cyclase activities. Discussion The large population and extensive characterization of subjects in this study provided an advantage over previous studies in which only the association of a few individual factors with adenylyl cyclase activity was investigated. The results demonstrate that although platelet adenylyl cyclase activity could be useful as a trait marker of alcohol dependence, its reliability in this regard is diminished by the influence of recent alcohol drinking and other variables. The associations between platelet adenylyl cyclase activities and marijuana abuse, as well as a history of depression, suggest that it may be worthwhile to study the genetic association of adenylyl cyclases (e.g., polymorphisms in the genes that code for particular adenylyl cyclase isoforms) with a predisposition to depression as well as to alcohol or marijuana abuse/dependence.

Platelet Adenylyl Cyclase Activity as a State or Trait Marker in Alcohol Dependence: Results of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence

There has been considerable interest in identifying biochemical markers indicative of a genetic predisposition to alcohol dependence ("trait markers"), as well as biochemical markers of recent alcohol drinking ("state markers"). Platelet adenylyl cyclase activity has been suggested as a trait and/or as a state marker related to alcohol dependence. We have now measured platelet adenylyl cyclase activity in more than 1400 well-characterized subjects, which allows us to investigate the influence of a broad range of factors on this activity. Subjects were recruited as part of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence and were interviewed by using the WHO/ISBRA Interview Schedule. Adenylyl cyclase activity (basal, cesium fluoride [CsF]-, forskolin- and Gpp(NH)p-stimulated activities) was measured in platelet samples that were obtained at the time of interview. Data were analyzed by multivariate regression analyses. The multivariate analyses revealed that recent abstinence from alcohol was associated with diminutions in platelet adenylyl cyclase activities. A positive family history of alcohol dependence was associated with higher levels of adenylyl cyclase activities, and there was a significant interaction between the effect of alcohol consumption in the past month and family history of alcohol dependence; that is, the influence of alcohol consumption depended on whether the individual had a positive family history. A history of marijuana abuse also was associated with higher levels of platelet adenylyl cyclase activities, and a history of major depression was associated with lower levels of forskolin- and CsF-stimulated activities. Sex, race, and site of recruitment also affected some adenylyl cyclase activities, but there was no significant association of alcohol dependence or abuse with any of the platelet adenylyl cyclase activities. The large population and extensive characterization of subjects in this study provided an advantage over previous studies in which only the association of a few individual factors with adenylyl cyclase activity was investigated. The results demonstrate that although platelet adenylyl cyclase activity could be useful as a trait marker of alcohol dependence, its reliability in this regard is diminished by the influence of recent alcohol drinking and other variables. The associations between platelet adenylyl cyclase activities and marijuana abuse, as well as a history of depression, suggest that it may be worthwhile to study the genetic association of adenylyl cyclases (e.g., polymorphisms in the genes that code for particular adenylyl cyclase isoforms) with a predisposition to depression as well as to alcohol or marijuana abuse/dependence.

15-Deoxy-delta 12,14-prostaglandins D2 and J2 are potent activators of human eosinophils.

15-Deoxy-Delta(12,14)-PDJ(2) (15d-PGJ(2)) is a degradation product of PGD(2) that has been proposed as an anti-inflammatory compound because of its various inhibitory effects, some of which are mediated by peroxisome proliferator-activated receptor-gamma. In contrast to its reported inhibitory effects on macrophages and other cells, we found that this compound is a potent activator of eosinophils, inducing calcium mobilization, actin polymerization, and CD11b expression. It is selective for eosinophils, having little or no effect on neutrophils or monocytes. 15d-PGJ(2) has an EC(50) of approximately 10 nM, similar to that of its precursor, PGD(2). The concentrations of 15d-PGJ(2) required to activate eosinophils are thus much lower than those required for its anti-inflammatory effects (usually micromolar). 15-Deoxy-Delta(12,14)-prostaglandin D(2) (15d-PGD(2)) is also a potent activator of eosinophils, with an EC(50) about the same as that of PGD(2), whereas Delta(12)-PGJ(2) is slightly less potent. Eosinophils pretreated with PGD(2) no longer respond to 15d-PGJ(2), and vice versa, but in both cases the cells still respond to another eicosanoid proinflammatory mediator, 5-oxo-6,8,11,14-eicosatetraenoic acid. This indicates that the effects of 15d-PGJ(2) are mediated by the DP(2)/chemoattractant receptor-homologous molecule expressed on Th2 cells that has recently been identified in eosinophils. 15d-PGJ(2) is selective for the DP(2) receptor, in that it has no effect on DP(1) receptor-mediated adenylyl cyclase activity in platelets. We conclude that 15d-PGJ(2) and 15d-PGD(2) are selective DP(2) receptor agonists that activate human eosinophils with potencies at least 100 times greater than those for the proposed anti-inflammatory effects of 15d-PGJ(2) on other cells.

WHP/ISBRA study on state and trait markers in alcoholism.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Boris Tabakoff. The presentations were (1) Overview of the WHO/ISBRA study on state and trait markers in alcoholism, by Boris Tabakoff; (2) Biochemical markers of acute and chronic drinking: Results of the WHO/ISBRA study, by Anders Helander; (3) The impact of country of recruitment and body mass index on biological marker dose-response curves in the WHO/ISBRA Study, by Kate M. Conigrave; (4) Relationship of body water to carbohydrate-deficient transferrin measures, by Larry Martinez; and (5) Platelet adenylyl cyclase activity as a trait marker of alcohol dependence, by Paula L. Hoffman.

WHO/ISBRA Study on State and Trait Markers in Alcoholism

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Boris Tabakoff. The presentations were (1) Overview of the WHO/ISBRA study on state and trait markers in alcoholism, by Boris Tabakoff; (2) Biochemical markers of acute and chronic drinking: Results of the WHO/ISBRA study, by Anders Helander; (3) The impact of country of recruitment and body mass index on biological marker dose‐response curves in the WHO/ISBRA Study, by Kate M. Conigrave; (4) Relationship of body water to carbohydrate‐deficient transferrin measures, by Larry Martinez; and (5) Platelet adenylyl cyclase activity as a trait marker of alcohol dependence, by Paula L. Hoffman.

Platelet Adenylyl Cyclase Activity as a Trait Marker of Alcohol Dependence

There is compelling evidence that genetic factors play a major role in the development of alcohol dependence. Platelet adenylyl cyclase (AC) activity has been proposed as a biochemical marker for differentiating alcohol-dependent and nondependent subjects, but the sensitivity and specificity of this marker have not been ascertained. The objective of this study was to determine the sensitivity and specificity of platelet AC activity in identifying alcohol-dependent subjects and to ascertain the effect of medical/ psychiatric variables, drinking and smoking history, and age and body weight on AC activity. The cross-sectional study was conducted from 1995 to 1998. Participants were 210 Australian White men who were community volunteers and alcohol treatment inpatients in Sydney, Australia. There were 41 nondrinkers, 140 drinkers, and 29 men who were entering alcohol treatment. The main outcome measure was platelet AC activity. Classification variables were plasma ethanol, gamma-glutamyltransferase, aspartate aminotransferase, serum carbohydrate-deficient transferrin (CDT), and urinary 5-hydroxytryptophol/5-hydroxyindoleacetic acid (5-HTOL/5-HIAA) levels, and World Health Organization/International Society for Biomedical Research on Alcoholism Interview Schedule variables, which included alcohol use and dependence criteria. Among subjects who reported abstinence for at least 4 days, both cesium fluoride (CsF)- and forskolin-stimulated platelet AC activities were significantly lower in those with a lifetime history of alcohol dependence compared with those with no such history (p < 0.005 and p < 0.05, respectively). The sensitivity and specificity of CsF-stimulated AC activity to discriminate individuals with a lifetime history of alcohol dependence were 75% and 79%, respectively. Similar values for sensitivity and specificity for CsF-stimulated AC activity were calculated when discriminating current alcohol dependence in the subjects in our sample. Irrespective of the history of alcohol dependence, persons who had consumed alcohol recently (within the last 3-4 days) showed significantly higher mean basal, CsF-stimulated, and forskolin-stimulated AC activity (p < 0.001), as did those who had elevated 5-HTOL/5-HIAA ratios or CDT levels, indicative of recent (heavy) drinking. The "normalization" of platelet AC activity to baseline levels after an individual stops drinking may be related to the generation of new platelets during the abstinence period. Conduct disorder and antisocial personality disorder were not associated with low AC activity, but low forskolin-stimulated AC activity was associated with major depression. We found that CsF- and forskolin-stimulated platelet AC activity discriminates between subjects with and without alcohol dependence in a population of subjects who had not consumed significant quantities of ethanol recently. Recent alcohol consumption is a confounding variable that can alter the measured levels of AC activity. Forskolin-stimulated platelet AC activity also may be influenced by a history of major depression.

Platelet Adenylyl Cyclase Activity as a Trait Marker of Alcohol Dependence

Background: There is compelling evidence that genetic factors play a major role in the development of alcohol dependence. Platelet adenylyl cyclase (AC) activity has been proposed as a biochemical marker for differentiating alcohol-dependent and nondependent subjects, but the sensitivity and specificity of this marker have not been ascertained. The objective of this study was to determine the sensitivity and specificity of platelet AC activity in identifying alcohol-dependent subjects and to ascertain the effect of medical/psychiatric variables, drinking and smoking history, and age and body weight on AC activity. Methods: The cross-sectional study was conducted from 1995 to 1998. Participants were 210 Australian White men who were community volunteers and alcohol treatment inpatients in Sydney, Australia. There were 41 nondrinkers, 140 drinkers, and 29 men who were entering alcohol treatment. The main outcome measure was platelet AC activity. Classification variables were plasma ethanol, γ-glutamyltransferase, aspartate aminotransferase, serum carbohydrate-deficient transferrin (CDT), and urinary5-hydroxytryptophol/5-hydroxyindoleacetic acid (5-HTOL/5-HIAA) levels, and World Health Organization/International Society for Biomedical Research on Alcoholism Interview Schedule variables, which included alcohol use and dependence criteria. Results: Among subjects who reported abstinence for at least 4 days, both cesium fluoride (CsF)- and forskolin-stimulated platelet AC activities were significantly lower in those with a lifetime history of alcohol dependence compared with those with no such history (p < 0.005 and p < 0.05, respectively). The sensitivity and specificity of CsF-stimulated AC activity to discriminate individuals with a lifetime history of alcohol dependence were 75% and 79%, respectively. Similar values for sensitivity and specificity for CsF-stimulated AC activity were calculated when discriminating current alcohol dependence in the subjects in our sample. Irrespective of the history of alcohol dependence, persons who had consumed alcohol recently (within the last 3–4 days) showed significantly higher mean basal, CsF-stimulated, and forskolin-stimulated AC activity (p < 0.001), as did those who had elevated 5-HTOL/5-HIAA ratios or CDT levels, indicative of recent (heavy) drinking. The “normalization” of platelet AC activity to baseline levels after an individual stops drinking may be related to the generation of new platelets during the abstinence period. Conduct disorder and antisocial personality disorder were not associated with low AC activity, but low forskolin-stimulated AC activity was associated with major depression. Conclusions: We found that CsF- and forskolin-stimulated platelet AC activity discriminates between subjects with and without alcohol dependence in a population of subjects who had not consumed significant quantities of ethanol recently. Recent alcohol consumption is a confounding variable that can alter the measured levels of AC activity. Forskolin-stimulated platelet AC activity also may be influenced by a history of major depression.

Platelet Adenylyl Cyclase Activity as a Biochemical Trait Marker for Predisposition to Alcoholism

Previous studies demonstrated a reduced Gs-protein stimulated adenylyl cyclase activity in the brain and blood cells of alcoholics. We investigated this phenomenon in platelets of children of alcoholics (COA), i.e., of children at high risk for the acquisition of alcoholism and (as yet) not regularly consuming alcohol. Gs-protein mediated stimulation of adenylyl cyclase by 30 mM NaF and 50 microM forskolin stimulated adenylyl cyclase activity were assessed in platelet membranes of 23 (male and female) COA and 20 control children. Gs-protein stimulated cAMP production by NaF, unlike that induced by direct stimulation of adenylyl cyclase with forskolin, in platelet membranes of COA was profoundly lower than in platelet membranes of control children. Moreover, such a reduced Gs-protein functioning was only observed in platelet membranes of COA with a multigenerational family history of alcoholism. A reduction of Gs-protein stimulated adenylyl cyclase activity in platelets may represent a sensitive and gender-independent trait marker for predisposition to alcoholism, rather than a state marker for alcoholism.

Platelet Adenylyl Cyclase Activity as a Biochemical Trait Marker for Predisposition to Alcoholism

Platelet Adenylyl Cyclase Activity as a Biochemical Trait Marker for Predisposition to Alcoholism

Platelet Adenylyl Cyclase Activity as a Biochemical Trait Marker for Predisposition to Alcoholism

Platelet Adenylyl Cyclase Activity as a Biochemical Trait Marker for Predisposition to Alcoholism

Effects of Abstinence and Family History for Alcoholism on Platelet Adenylyl Cyclase Activity

Platelet adenylyl cyclase (AC) activity was measured in 32 alcohol-dependent subjects and 27 control subjects who were categorized as either family history-positive (FHP) or family history-negative (FHN) for alcoholism. The interview and blood sample collections were performed shortly after cessation of heavy drinking in the alcoholic group, and repeat blood samples were obtained at the end of the first and second weeks of monitored abstinence. Control subjects received the same interview and provided blood samples at the time of the interview. When subjects were not segregated for FHP or FHN status, there were no statistically significant differences in basal, cesium fluoride (CsF)-, or forskolin-stimulated mean AC activities between the controls and the alcoholics, at study entry or with 1 or 2 weeks of abstinence. On the other hand, over the 2-week course of sobriety from heavy drinking, the CsF-stimulated AC activity of FHP alcohol-dependent subjects decreased significantly (p = 0.03). FHP alcohol-dependent subjects after 2 weeks of sobriety had significantly lower mean CsF-stimulated AC activity than FHN controls (p = 0.04), whereas the FHN alcoholic subjects' CsF-stimulated AC activity did not differ significantly from FHN controls at this point in time. When all subjects were pooled and then categorized as either FHP or FHN, there was a significant difference in mean CsF-stimulated AC activity (p = 0.02) between the FHP and FHN subject groups. Genetic factors and abstinence appear to have roles in determining low platelet AC activity in alcoholic and nonalcoholic subjects. CsF-stimulated platelet AC activity, in particular, appears to act as a trait marker for a genetic vulnerability to developing alcoholism, but recent heavy drinking in male alcoholics is a factor that can mask differences between FHP and FHN subjects.

Effects of Abstinence and Family History for Alcoholism on Platelet Adenylyl Cyclase Activity

Platelet adenylyl cyclase (AC) activity was measured in 32 alcohol-dependent subjects and 27 control subjects who were categorized as either family history-positive (FHP) or family history-negative (FHN) for alcoholism. The interview and blood sample collections were performed shortly after cessation of heavy drinking in the alcoholic group, and repeat blood samples were obtained at the end of the first and second weeks of monitored abstinence. Control subjects received the same interview and provided blood samples at the time of the interview. When subjects were not segregated for FHP or FHN status, there were no statistically significant differences in basal, cesium fluoride (CsF)-, orforskolin-stimulated mean AC activities between the controls and the alcoholics, at study entry or with 1 or 2 weeks of abstinence. On the other hand, over the 2-week course of sobriety from heavy drinking, the CsF-stimulated AC activity of FHP alcohol-dependent subjects decreased significantly (p = 0.03). FHP alcohol-dependent subjects after 2 weeks of sobriety had significantly lower mean CsF-stimulated AC activity than FHN controls (p = 0.04), whereas the FHN alcoholic subjects' CsF-stimulated AC activity did not differ significantly from FHN controls at this point in time. When all subjects were pooled and then categorized as either FHP or FHN, there was a significant difference in mean CsF-stimulated AC activity (p = 0.02) between the FHP and FHN subject groups. Genetic factors and abstinence appear to have roles in determining low platelet AC activity in alcoholic and nonalcoholic subjects. CsF-stimulated platelet AC activity, in particular, appears to act as a trait marker for a genetic vulnerability to developing alcoholism, but recent heavy drinking in male alcoholics is a factor that can mask differences between FHP and FHN subjects.

An Initial Study of the Relationship Between Platelet Adenylyl Cyclase Activity and Alcohol Use Disorder Criteria

Low platelet adenylyl cyclase (AC) activity has been previously proposed to be a trait marker reflecting a genetic predisposition to alcohol dependence. To determine whether low platelet AC activity in alcohol-dependent subjects may be related to specific diagnostic criteria of DSM-IV and ICD-10 alcohol use disorders, we analyzed responses obtained in structured clinical interviews of 36 subjects who were determined to be alcohol-dependent Platelet AC activity when stimulated by guanylyl-imidodiphosphate [Gpp(NH)p] or forskolin was significantly lower in alcohol-dependent subjects as a group, compared with controls. When we analyzed the responses of the alcohol-dependent subjects to questions used to establish the diagnosis of alcohol abuse/dependence and dichotomized the subjects by positive or negative responses, we found that Gpp(NH)p- and forskolin-stimulated platelet AC activities were significantly lower among those alcohol-dependent subjects who had positive responses to questions related to drinking despite negative effects on mood ("Did you ever continue to drink even though you knew it was making you feel depressed, uninterested in things, or suspicious or distrustful of other people?"), drinking despite negative effects on health ("Did you ever continue to drink even though you knew it was causing you a health problem or making a health problem worse?"), or violence when drinking ("Did you get into physical fights while drinking or right after drinking?"). The alcohol-dependent subjects who had negative responses to these questions exhibited Gpp(NH)p- and forskolin-stimulated platelet AC activity that did not differ significantly from values in control subjects. The DSM-IV diagnosis of antisocial personality disorder did not distinguish alcohol-dependent subjects with regard to platelet AC activity. Gpp(NH)p and forskolin-stimulated AC activity may distinguish certain subtypes of alcoholics (i.e., those who develop negative mood in response to drinking, those who continue drinking despite health effects, and those who become violent while drinking).