Biomedical subjects

D Hommer

Publications and source records attributed to D Hommer.

At least 19 recordsLinked to original sources

PubMed2002

Relationship between cortisol and serotonin metabolites and transporters in alcoholism [correction of alcolholism].

BACKGROUND: Stress hormone activation may induce clinical depression via an interference with central serotonergic neurotransmission. In alcoholics, a reduction in serotonin transporters was associated with clinical depression, and an activation of cortisol secretion is frequently found during detoxification. We assessed the interaction between stress hormone activation, serotonin transporters, monoamine metabolites in the cerebrospinal fluid (CSF), and mood states in male and female alcoholics and healthy control subjects. METHODS: The availability of serotonin transporters was measured with [I-123]beta-CIT and SPECT in the raphe area of the brainstem in 31 alcoholics after four weeks of abstinence and in 25 age-matched healthy volunteers. Concentrations of plasma cortisol were measured on the day of the SPECT scan. Within one week after the SPECT scan, we assessed monoamine metabolites and corticotropin-releasing factor (CRF) in the CSF. RESULTS: Clinical depression was associated with a reduction in serotonin transporter availability among male alcoholics. Among male alcoholics and healthy volunteers, CSF 5-HIAA and plasma cortisol concentrations were inversely correlated with the availability of raphe serotonin transporters and positively correlated with the severity of clinical depression. No significant correlations were observed between raphe serotonin transporters and HVA, MHPG and CRF concentrations in the CSF. CONCLUSION: Our findings support the hypothesis of an interaction between reduced serotonin transporters, stress hormone activation and clinical depression. They confirm the hypothesis that serotonergic neurotransmission dysfunction in alcoholism is limited to male alcoholics. The observed interactions between high cortisol concentrations and reduced serotonin transporter availability warrant further studies in major depression and other neuropsychiatric diseases with implied cortisol activation and serotonergic dysfunction.

Adult↗

PubMed2001

Dissociation of reward anticipation and outcome with event-related fMRI.

Reward processing involves both appetitive and consummatory phases. We sought to examine whether reward anticipation vs outcomes would recruit different regions of ventral forebrain circuitry using event-related fMRI. Nine healthy volunteers participated in a monetary incentive delays task in which they either responded to a cued target for monetary reward, responded to a cued target for no reward, or did not respond to a cued target during scanning. Multiple regression analyses indicated that while anticipation of reward vs non-reward activated foci in the ventral striatum, reward vs non-reward outcomes activated foci in the ventromedial frontal cortex. These findings suggest that reward anticipation and outcomes may differentially recruit distinct regions that lie along the trajectory of ascending dopamine projections.

Adult↗

PubMed2001

Negative association of neuroticism with brain volume ratio in healthy humans.

BACKGROUND: Brain volume decreases with normal aging. We sought to determine whether, in addition to age, individual differences in stress reactivity (i.e., neuroticism) would also predict reductions in brain volume. METHODS: Brain volume ratios were calculated for a sample of 86 healthy volunteers, based on segmented brain volumes taken from T(1)-weighted magnetic resonance imaging and corrected for intracranial volume. Standardized self-reported measures of dispositional neuroticism were concurrently obtained by administering the Revised NEO Personality Inventory. RESULTS: After statistically controlling for age and sex, neuroticism showed a significant negative association with the ratio of brain to the remainder of the intracranial volume, but was not related to intracranial volume itself. In particular, subfactors of neuroticism related to the chronic experience of arousing negative emotions were associated with reduced brain ratio. CONCLUSIONS: These results suggest that individual differences in stress reactivity contribute to reductions in brain volume observed during adulthood.

Adult↗

PubMed2001

Anticipation of increasing monetary reward selectively recruits nucleus accumbens.

Comparative studies have implicated the nucleus accumbens (NAcc) in the anticipation of incentives, but the relative responsiveness of this neural substrate during anticipation of rewards versus punishments remains unclear. Using event-related functional magnetic resonance imaging, we investigated whether the anticipation of increasing monetary rewards and punishments would increase NAcc blood oxygen level-dependent contrast (hereafter, "activation") in eight healthy volunteers. Whereas anticipation of increasing rewards elicited both increasing self-reported happiness and NAcc activation, anticipation of increasing punishment elicited neither. However, anticipation of both rewards and punishments activated a different striatal region (the medial caudate). At the highest reward level ($5.00), NAcc activation was correlated with individual differences in self-reported happiness elicited by the reward cues. These findings suggest that whereas other striatal areas may code for expected incentive magnitude, a region in the NAcc codes for expected positive incentive value.

Adult↗

PubMed2001

Evidence for a gender-related effect of alcoholism on brain volumes.

OBJECTIVE: The goal of this study was to compare brain volumes of alcoholic and nonalcoholic men and women and determine if the magnitudes of differences in brain volumes between alcoholic women and nonalcoholic women are greater than the magnitudes of the differences between alcoholic men and nonalcoholic men. METHOD: The study group included 118 subjects: 79 inpatients 30-60 years of age who were alcohol dependent but had no clinically apparent cognitive impairment or medical illness (43 men and 36 women) and 39 healthy comparison subjects of similar age who were not alcoholic (20 men and 19 women). The volume of intracranial contents was segmented into gray matter, white matter, sulcal CSF, and ventricular CSF from a T(1)-weighted magnetic resonance image obtained after the alcoholic subjects had attained 3 weeks of sobriety. RESULTS: Alcoholic women had significantly smaller volumes of gray and white matter as well as greater volumes of sulcal and ventricular CSF than nonalcoholic women. The differences in gray and white matter volumes between alcoholic and nonalcoholic men were significant, but the significance of these differences was of a smaller magnitude than the significance of the differences between alcoholic and nonalcoholic women. Direct comparisons of alcoholic men and women showed that the proportion of intracranial contents occupied by gray matter was smaller in alcoholic women than in alcoholic men. The magnitudes of differences in brain volumes adjusted for intracranial size between alcoholic women and nonalcoholic women were greater than the magnitudes of the adjusted differences between alcoholic men and nonalcoholic men. CONCLUSIONS: These results are consistent with greater sensitivity to alcohol neurotoxicity among women.

Adult↗

PubMed2000

Lactate-induced rage and panic in a select group of subjects who perpetrate acts of domestic violence.

BACKGROUND: Perpetrators of domestic violence frequently report symptoms of autonomic arousal and a sense of fear and/or loss of control at the time of the violence. Since many of these symptoms are also associated with panic attacks, we hypothesized that perpetrators of domestic violence and patients with panic attacks may share similar exaggerated fear-related behaviors. To test this hypothesis, we employed the panicogenic agent sodium lactate to examine the response of perpetrators to anxiety fear induced by a chemical agent. METHODS: Using a double-blind, placebo-controlled design, we infused 0.5 mol/L sodium lactate or placebo over 20 min on separate days to a select group of subjects who perpetrate acts of domestic violence and two nonviolent comparison groups. We compared their behavioral, neuroendocrine, and physiologic responses. RESULTS: Lactate administration elicited intense emotional responses in the perpetrators of domestic violence. Perpetrators evidenced more lactate-induced rage and panic and showed greater changes in speech, breathing, and motor activity than did nonviolent control subjects. There were no significant differences between the groups for any neuroendocrine or physiologic measure. CONCLUSIONS: These results are consistent with our hypothesis that some perpetrators of domestic violence have exaggerated fear-related behavioral responses.

Adult↗

PubMed2000

A relationship between serotonin transporter genotype and in vivo protein expression and alcohol neurotoxicity.

BACKGROUND: Genetic variation of the promoter for the serotonin transporter (5-HTT) gene has been associated with its functional capacity. In vitro, carriers of a short allele (s-carriers) of the 5-HTT promoter display significant reduction in 5-HTT capacity. Dysfunction of 5-HTT has been observed in alcoholic individuals. We assessed whether the allelic constitution of the 5-HTT gene is associated with reduced serotonin transporter availability among alcoholic individuals. METHODS: We genotyped the 5-HTT promoter region and measured the availability of serotonin transporter protein with [I-123]beta-CIT SPECT in the raphe area in 14 abstinent male alcoholic subjects and 8 age-matched control subjects of European American descent. RESULTS: Among control subjects, the ratio of in vivo 5-HTT availability for ll-homozygous individuals relative to s-carriers was comparable to serotonin uptake ratios measured in vitro. There was a significant interaction of diagnosis and 5-HTT promoter genotype on 5-HTT availability (p <.01). Among controls, ll-homozygous individuals displayed a significant increase as compared with s-carriers. The availability of raphe 5-HTT was significantly reduced in ll-homozygous alcoholic individuals and was negatively correlated with their amount of alcohol consumption. Among s-carriers, 5-HTT availability did not differ significantly between control and alcoholic subjects. CONCLUSIONS: Our preliminary findings suggest an association between 5-HTT allelic constitution and in vivo measurements of human serotonin transporter availability, and a potentially selective susceptibility of ll-homozygous individuals to the neurotoxic effects of chronic excessive alcohol consumption.

Adult↗

PubMed2000

FMRI visualization of brain activity during a monetary incentive delay task.

Comparative studies have implicated striatal and mesial forebrain circuitry in the generation of autonomic, endocrine, and behavioral responses for incentives. Using blood oxygen level-dependent functional magnetic resonance imaging, we sought to visualize functional activation of these regions in 12 normal volunteers as they anticipated and responded for monetary incentives. Both individual and group analyses of time-series data revealed significant activation of striatal and mesial forebrain structures (including insula, caudate, putamen, and mesial prefrontal cortex) during trials involving both monetary rewards and punishments. In addition to these areas, during trials involving punishment, group analysis revealed activation foci in the anterior cingulate and thalamus. These results corroborate comparative studies which implicate striatal and mesial forebrain circuitry in the elaboration of incentive-driven behavior. This report also introduces a new paradigm for probing the functional integrity of this circuitry in humans.

Adult↗

PubMed2000

Genotype influences in vivo dopamine transporter availability in human striatum.

In vivo availability of striatal dopamine transporter (DAT) protein has been reported to be reduced among alcoholics, and allelic variation of the DAT gene (SLC6A3) has been associated with severity of alcohol withdrawal. We examined the VNTR polymorphism of the 3' untranslated region of SLC6A3 and DAT protein availability in 14 abstinent alcoholics and 11 control subjects. Single photon emission computed tomography (SPECT) and plasma levels of the radioligand [I-123]beta-CIT were used to quantify DAT protein availability. Individuals with the 9-repeat/10-repeat genotype had a mean 22% reduction of DAT protein availability in putamen compared with 10-repeat homozygous individuals (t = 2.14, df = 23, p < .05). Consistent with earlier studies, alcoholism, per se, was not significantly associated with either DAT availability or DAT genotype. These findings suggest that the VNTR polymorphism of the DAT gene effects translation of the DAT protein. This effect may explain a variety of clinical associations that have been reported with this polymorphism.

3' Untranslated Regions↗

PubMed2000

The suitability of [11C]-alpha-methyl-L-tryptophan as a tracer for serotonin synthesis: studies with dual administration of [11C] and [14C] labeled tracer.

The tracer [11C]-alpha-methyl-L-tryptophan (alphaMTP) has been used to measure brain serotonin synthesis rates with positron emission tomography (PET). To address questions about the accuracy of the kinetic model, [14C]alphaMTP was used to directly measure conversion to [14C]-alpha-methyl-serotonin (alphaM5HT) in monkeys that had been previously studied with PET and [11C]alphaMTP. Four male, fasted, isoflurane-anesthetized rhesus monkeys were studied with [11C]alphaMTP and PET. Immediately after the initial 3-hour scan, a second dose of [11C]alphaMTP was coinjected with 1 mCi of [14C]alphaMTP, and additional PET data were collected. Approximately 90 minutes after the second alphaMTP administration, the animals were killed with an overdose of phenobarbital, and brain samples from 21 regions were taken and analyzed by HPLC. Minimal conversion of alphaMTP to alphaM5HT occurred; HPLC analysis of 14C radioactivity showed that greater than 96% of the total counts were in fractions corresponding to the alphaMTP peak. Brain concentrations of serotonin, tryptophan, 5-hydroxyindole-3-acetic acid, and alphaMTP also were determined fluorometrically using external quantification. Patlak plots generated from PET images acquired over 3 hours showed no time period of linear increase, and final slopes were not significantly different from zero, consistent with the finding of minimal conversion to [14C]alphaM5HT. These data indicate that in the 3-hour period after injection, [11C]alphaMTP is acting predominantly as a tracer of tryptophan uptake, not serotonin synthesis.

Animals↗

PubMed1999

Severity of depression in abstinent alcoholics is associated with monoamine metabolites and dehydroepiandrosterone-sulfate concentrations.

Depressed mood increases the relapse risk of abstinent alcoholics; its neurobiological correlates may include reduced serotonin and norepinephrine turnover rates and increased cortisol concentrations during detoxification stress. Neurosteroids such as dehydroepiandrosterone and its sulfate (DHEA and DHEA-S) may antagonize cortisol action and may have mood-elevating effects on their own. We measured severity of depression with Beck's Depression Inventory (BDI) and Hamilton's Depression Rating Scale (HDRS), plasma concentrations of cortisol, DHEA and DHEA-S, and CSF concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), the norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) and the dopamine metabolite homovanillic acid (HVA) in 21 abstinent alcoholics after 4 weeks of abstinence and in 11 age-matched healthy control subjects. Only CSF MHPG concentrations were reduced in alcoholics compared to control subjects (41.4 +/- 6.6 vs. 53.3 +/- 8.6 pmol/ml). Self-rated depression was significantly correlated with CSF MHPG (Spearman's R = +0.57, P < 0.01), CSF 5-HIAA (R = +0.51, P < 0.05) and plasma cortisol concentrations (R = +0.50, P < 0.05). Negative correlations were found between DHEA-S concentrations and both self-rated depression (R = -0.45, P < 0.05) and observer-rated depression (R = -0.55, P < 0.05). The ratio of DHEA-S to cortisol serum concentrations was also negatively correlated with depression (BDI: R = -0.55, P < 0.01; HDRS: R = -0.63, P < 0.005). Anxiety (Spielberger's State Anxiety Scale) was only associated with CSF MHPG concentrations (R = +0.58, P < 0.01). Our findings point to the importance of noradrenergic dysfunction in the pathogenesis of depression among abstinent alcoholics and indicate that their mood states may also be modulated by a low DHEA-S to cortisol ratio, hypothetically indicative of low stress protection capacities.

Adult↗

PubMed1999

Effects of acute tryptophan depletion on plasma and cerebrospinal fluid tryptophan and 5-hydroxyindoleacetic acid in normal volunteers.

Brain serotonin synthesis and metabolism (turnover), as indicated by CSF concentrations of 5-hydroxyindoleacetic acid (5-HIAA), may depend on plasma concentrations of the essential amino acid L-tryptophan (TRP). We investigated the biochemical effects of acute plasma TRP depletion (ATD) in normal volunteers undergoing a 36-h CSF collection via lumbar drain. Six subjects who were in good health were put on a low-TRP diet (160 mg/day) 24 h before lumbar puncture; this diet was continued for the first 22 h of the CSF collection. At hour 22, subjects ingested a TRP-deficient 15-amino acid drink shown previously to deplete plasma TRP. Total plasma TRP, free plasma TRP, and CSF TRP subsequently decreased 86.3, 86.5, and 92.3%, respectively. CSF 5-HIAA decreased by 32.8%. Plasma total and free TRP concentrations were both decreased at approximately 2 h following ingestion of the TRP-free amino acid drink and were lowest approximately 6 h after ATD; CSF TRP and 5-HIAA were decreased at 2.5 h and approximately 4 h after ATD, respectively. CSF TRP was lowest 8.0 h later. CSF 5-HIAA continued to decrease 14 h after the TRP-deficient amino acid drink was given.

Adult↗

PubMed1999

Effects of alcohol use and gender on the dynamics of EKG time-series data.

Hurst analysis of EKG data obtained from a population of alcoholic (n = 13) and nonalcoholic (n = 48) subjects was undertaken. Potential subjects (n = 120) were screened using the Schedule for Affective Disorders and Schizophrenia and Structured Clinical Interview for DSM-III instruments. Data from subjects with a diagnosis of current alcohol dependence were analyzed. Subjects with diagnoses such as major depression, bipolar disorder or schizophrenia (Axis I diagnoses), or personality disorders (Axis II diagnoses) were excluded from analysis. Subjects undergoing testing were free of alcohol and illicit drugs. Alcoholic subjects had no clinical evidence of alcohol withdrawal symptoms at the time of testing. EKG data were obtained with eyes open or with eyes closed. Approximately 3.5 min of data were obtained for each condition. Alcoholic subjects had less complex heart rate dynamics as evidenced by higher values of H = 0.18 +/- 0.05 (mean +/- SEM), compared with healthy comparison subjects with H = 0.09 +/- 0.02, p < 0.014 for the eyes closed condition, and H = 0.17 +/- 0.05 (mean +/- SEM) compared with healthy comparison subjects with H = 0.07 +/- 0.02,p < 0.011 for the eyes open condition. A gender effect was seen, with female subjects showing evidence of more complex heart rate dynamics than male subjects.

Alcohol Drinking↗

PubMed1998

Brain serotonin synthesis rates in rhesus monkeys determined by [11C]alpha-methyl-L-tryptophan and positron emission tomography compared to CSF 5-hydroxyindole-3-acetic acid concentrations.

Twelve male, fasted, anesthetized rhesus monkeys were studied with positron emission tomography (PET) and [11C]alpha-methyl-L-tryptophan (alpha MTP) to determine serotonin synthesis rates as described by Diksic et al. (1991). It was expected that the serotonin synthesis rates determined for the whole brain would be correlated with CSF 5-hydroxyindole-3-acetic acid concentrations, a measure of central serotonin turnover, because both measures were obtained at steady state. However, no significant correlation was found. During data analysis, it was noticed that the calculated serotonin synthesis rates were significantly correlated to free plasma tryptophan (TP) concentrations (r = 0.88, p < .001). From repeat scans conducted in six monkeys, it was determined that day-to-day variability in free plasma TP and the percentage of protein binding (average percent difference was 48 and 37%, respectively) produced most of the variability in the calculated serotonin synthesis rates (50%); repeat K images, obtained from the PET data alone, differed by only 11%. Calculated serotonin synthesis rates reported for [11C]alpha MTP PET studies of humans (Nishizawa et al. 1997) and dogs (Diksic et al. 1991) were also highly correlated to reported differences in plasma free TP concentrations. It seems that the [11C]alpha MTP model for the computation of serotonin synthesis rates is very dependent on plasma free TP concentration and that it may not accurately determine actual serotonin synthesis rates.

Animals↗

PubMed1998

Reduced central serotonin transporters in alcoholism.

OBJECTIVE: Dysfunction of monoamine uptake mechanisms has been implicated in the pathogenesis of alcohol dependence. The authors explored whether serotonergic dysfunction is associated with anxiety and depression, which increase the risk of relapse in alcoholics. METHOD: The availability of serotonin and dopamine transporters in 22 male alcoholics and 13 healthy male volunteers was measured with the use of [123I] beta-CIT and single photon emission computed tomography, and psychopathological correlates were assessed. RESULTS: A significant reduction (a mean of about 30%) in the availability of brainstem serotonin transporters was found in the alcoholics, which was significantly correlated with lifetime alcohol consumption and with ratings of depression and anxiety during withdrawal. CONCLUSIONS: The findings support the hypothesis of serotonergic dysfunction in alcoholism and in withdrawal-emergent depressive symptoms.

Adult↗

PubMed1998

In vivo association between alcohol intoxication, aggression, and serotonin transporter availability in nonhuman primates.

OBJECTIVE: Studies on brain serotonin metabolism in human and nonhuman primates have indicated that dysfunction of serotonin transmission may play a role in the biological vulnerability to dependence on alcohol. Among young men, low sensitivity to alcohol intoxication predicts subsequent alcohol abuse and dependence. METHOD: The authors used single photon emission computed tomography and the radioligand [(I)123]beta-CIT ([(I)123]methyl 3beta-(4-iodophenyl) tropane-2-carboxylate) to measure the availability of serotonin transporters in 11 male rhesus monkeys, and the monkeys were genotyped for a functional polymorphism of the serotonin transporter gene. The 11 monkeys had experienced parental separation after birth; their behavior and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in CSF had been assessed regularly. RESULTS: In the 5-year-old monkeys, there was a significant negative correlation between beta-CIT binding to serotonin transporters in the brainstem and 5-HIAA concentrations in CSF. Animals with greater beta-CIT binding and low CSF 5-HIAA concentrations displayed greater aggressiveness and were less sensitive to alcohol-induced intoxication. The genetic constitution of the serotonin transporter promoter gene did not significantly contribute to the availability of brainstem serotonin transporters as measured by beta-CIT binding. CONCLUSIONS: In adult nonhuman primates who underwent early developmental stress, variables indicating a low serotonin turnover rate were associated with behavior patterns similar to those predisposing to early-onset alcoholism among humans.

Adult↗

PubMed1997

Effects of m-chlorophenylpiperazine on regional brain glucose utilization: a positron emission tomographic comparison of alcoholic and control subjects.

m-Chlorophenylpiperazine (mCPP) is a mixed serotonin agonist/antagonist used extensively in psychiatric research. Alcoholics show blunted neuroendocrine responses to mCPP, and in some settings mCPP can induce craving for alcohol, particularly among early onset alcoholics. We used 2-[18F]-2-deoxy-D-glucose positron emission tomography to examine the effects of intravenously administered mCPP (0.08 mg/kg) on brain glucose utilization in a group of 18 male alcoholics and 12 healthy male control subjects. Differences between two sequential scans (the first followed placebo and the second followed mCPP) were evaluated statistically with a Gaussian random field-based method. Among healthy volunteers mCPP significantly increased brain glucose metabolism in the right medial and posterior orbital gyrus, the cerebellar hemispheres bilaterally, the left nucleus accumbens, the head of the caudate nucleus bilaterally, the anterior and medial-dorsal nuclei of the thalamus bilaterally, the middle frontal gyrus, the left insular cortex, the left middle temporal gyrus, and the posterior cingulate gyrus. Among alcoholic subjects mCPP significantly increased brain glucose metabolism in larger areas of the cerebellum and posterior cingulate than it did in healthy volunteers, but compared with the healthy volunteers, alcoholics showed a smaller area of mCPP-induced activation in the thalamus, almost no activation in the orbital cortices, and no activation at all in the head of the caudate nucleus or the middle frontal gyrus. These results suggest that a serotoninergic challenge activates basal ganglia circuits involving orbital and prefrontal cortices among healthy volunteers but that the response of these circuits is blunted among alcoholics.

Adult↗

PubMed1996

Decreased corpus callosum size among alcoholic women.

BACKGROUND: Although females appear to be more sensitive to the hepatic consequences of alcoholism, it is not clear if women are more sensitive to the effects of excessive alcohol consumption on the brain than men. SUBJECTS AND METHODS: We compared the cross-sectional area of the corpus callosum in a group of 14 hospitalized alcoholic women and 13 hospitalized alcoholic men with a group of nine nonalcoholic women and 10 nonalcoholic men. All subjects were between the ages of 30 and 50 years. The cross-sectional areas of the corpus callosum and the inner table of the skull were measured on midsagittal T1-weighted magnetic resonance images. RESULTS: Females had smaller intracranial areas than males, but there was no difference in intracranial area between the alcoholics and nonalcoholics. The corpus callosum area was significantly smaller among the alcoholic women compared with either the control women or the alcoholic men. Alcoholic men did not differ from control men in the corpus callosum area. These results did not change when the corpus callosum area was adjusted for intracranial area by analysis of covariance. When the corpus callosum was divided into four segments of equal length, the reduction in area was not localized to any particular region. CONCLUSION: These results suggest an increased sensitivity to alcohol-induced brain damage among alcoholic women compared with alcoholic men.

Adult↗