Human CRH stimulation response during acute withdrawal and after medium-term abstention from alcohol abuse

An opponent process for alcohol addiction based on changes in endocrine gland mass

Consuming addictive drugs is often initially pleasurable, but escalating drug intake eventually recruits physiological anti-reward systems called opponent processes that cause tolerance and withdrawal symptoms. Opponent processes are fundamental for the addiction process, but their physiological basis is not fully characterized. Here, we propose an opponent processes mechanism centered on the endocrine stress response, the hypothalamic-pituitary-adrenal (HPA) axis. We focus on alcohol addiction, where the HPA axis is activated and secretes β-endorphin, causing euphoria and analgesia. Using a mathematical model, we show that slow changes in the functional mass of HPA glands act as an opponent process for β-endorphin secretion. The model explains hormone dynamics in alcohol addiction and experiments on alcohol preference in rodents. The opponent process is based on fold-change detection (FCD) where β-endorphin responses are relative rather than absolute; FCD confers vulnerability to addiction but has adaptive roles for learning. Our model suggests gland mass changes as potential targets for intervention in addiction.

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Addiction involves tolerance and withdrawal over weeks

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Model of the HPA-axis and β-endorphins explains tolerance and withdrawal

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Effects due to changes in the functional mass of endocrine glands

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Fold-change detection makes circuit prone to addiction but boosts learning

A new model for the HPA axis explains dysregulation of stress hormones on the timescale of weeks

Stress activates a complex network of hormones known as the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is dysregulated in chronic stress and psychiatric disorders, but the origin of this dysregulation is unclear and cannot be explained by current HPA models. To address this, we developed a mathematical model for the HPA axis that incorporates changes in the total functional mass of the HPA hormone-secreting glands. The mass changes are caused by HPA hormones which act as growth factors for the glands in the axis. We find that the HPA axis shows the property of dynamical compensation, where gland masses adjust over weeks to buffer variation in physiological parameters. These mass changes explain the experimental findings on dysregulation of cortisol and ACTH dynamics in alcoholism, anorexia, and postpartum. Dysregulation occurs for a wide range of parameters and is exacerbated by impaired glucocorticoid receptor (GR) feedback, providing an explanation for the implication of GR in mood disorders. These findings suggest that gland-mass dynamics may play an important role in the pathophysiology of stress-related disorders.

Alterations in circadian rhythms following alcohol use: A systematic review

Increasing evidence suggest a bidirectional link between disrupted circadian rhythms and alcohol use disorders (AUD). A better understanding of these alcohol-induced changes in circadian rhythms will likely provide important therapeutic solutions. We conducted a systematic review based on the PubMed database examining biological rhythms in all stages of alcohol use: acute alcohol consumption, AUD, alcohol withdrawal, and abstinence. Different changes in circadian rhythms have been observed after a single acute alcohol intake, but also during AUD and alcohol withdrawal. Following a single acute alcohol intake, changes in biological rhythms are dose-dependent, reflected in the melatonin and cortisol secretions, and the core body temperature (CBT) rhythms. These alterations normalize the next morning and appear mostly for acute alcohol intake higher than 0.5 g/kg. These alterations are more severe during AUD and persist over time. In addition, interestingly, opposite patterns of the melatonin physiological ratio between diurnal and nocturnal secretion (N/D ratio < 1) have been observed during AUD and appear to be a marker of chronic daily use. During alcohol withdrawal, circadian rhythms desynchronization correlates with the severity of alcohol withdrawal symptoms and withdrawal complications such as delirium tremens. During abstinence a resynchronization of circadian rhythms of cortisol and CBT appears in most patients about 1 month after alcohol withdrawal. Disruption of melatonin circadian rhythms can persist after 3-12 weeks of abstinence. The circadian genetic vulnerability associated with biological rhythms alterations in alcohol use disorders increases the risk of relapses. Circadian-based interventions could play a critical role in preventing and treating AUD.

Ketamine administration during a critical period after forced ethanol abstinence inhibits the development of time-dependent affective disturbances

Forced abstinence from chronic two bottle-choice ethanol drinking produces the development of negative affective states in female C57BL/6J mice. We previously reported that this disrupted behavior is acutely reversed by administration of ketamine 30 min-prior to testing. Here we assessed whether ketamine can be used as an inoculant against the development of abstinence- dependent affective disturbances. In parallel, we examined the impact of ketamine administration on long-term potentiation (LTP) in the bed nucleus of the stria terminalis (BNST), a region implicated in affective disturbances. We administered ketamine (3 mg/kg i.p.) to female C57BL/6J mice with a history of chronic ethanol drinking at either the onset, two, or 6 days- post-abstinence and observed its impact on affective behavior in the elevated plus maze (EPM), the Novelty Suppressed Feeding Test (NSFT), and the Forced Swim Test (FST). In addition, we assessed BNST synaptic plasticity with field potential electrophysiology two to 3 weeks into abstinence. We found that early abstinence was associated with disrupted behavior on the EPM. Ketamine administered at the onset of forced abstinence prevented both the deficit in early EPM behavior, and the delayed deficits in NSFT and FST. However, ketamine administered either two or 6 days post-abstinence failed to prevent the abstinence-induced affective disturbances. To begin to explore potential alterations in neural circuit activity that accompanies these actions of ketamine, we assessed the impact of ketamine administration at the onset of forced abstinence and measured LTP induction in the BNST. We find that early ketamine administration persistently increased the capacity for LTP within the BNST. These findings suggest a critical period at the onset of forced abstinence in which ketamine inoculation can prevent the development of affective disturbances, in part by enhancing plasticity within the BNST.

Magnocellular hypothalamic system and its interaction with the hypothalamo-pituitary-adrenal axis

The hypothalamo-neurohypophyseal system plays a key role in maintaining homeostasis and in regulation of numerous adaptive reactions, e.g., endocrine stress response. Nonapeptides vasopressin and oxytocin are the major hormones of this system. They are synthesized by magnocellular neurons of the paraventricular and supraoptic hypothalamic nuclei. Magnocellular vasopressin is known to be one of the main physiological regulators of water-electrolyte balance. Its importance for control of the hypothalamo-pituitary-adrenal axis has been widely described. Magnocellular oxytocin is secreted predominantly during lactation and parturition. The complex actions of oxytocin within the brain include control of reproductive behavior and its involvement in central stress response to different stimuli. It's neuroendocrine basis is activation of the hypothalamo-pituitary-adrenal axis: corticotropin-releasing hormone is synthesized in parvocellular neurons of the paraventricular hypothalamic nuclei. The transitory coexpression of vasopressin in these cells upon stress has been described. Glucocorticoids, the end products of the hypothalamo-pituitary-adrenal axis have both central and peripheral actions. Their availability to target tissues is mainly dependent on systemic levels of corticosteroid-binding globulin. Intrinsic expression of this protein in different brain regions in neurons and glial cells has been recently demonstrated. Regulation of the hypothalamo-pituitary-adrenal axis and hypothalamo-neurohypophyseal system is highly complex. The role of both systems in the pathogenesis of various chronic ailments in humans has extensively been studied. Their disturbed functioning seems to be linked to various psychiatric, autoimmune and cardiovascular pathologies.

Modulation of proopiomelanocortin gene expression by ethanol in mouse anterior pituitary corticotrope tumor cell AtT20

In humans, alcoholism is associated with a decrease in basal ACTH and cortisol levels, and blunted pituitary ACTH responses to administered corticotropin-releasing hormone (CRH) during active drinking and after long-term abstinence. Preclinical studies indicate that a persistent decrease in pituitary activation after chronic exposure to ethanol is due to a direct effect of ethanol on the corticotrope of the anterior pituitary. The present studies were undertaken to determine if ethanol has effects on proopiomelanocortin (POMC) gene transcription activity in mouse anterior pituitary corticotrope tumor cell AtT20. We measured the levels of the POMC primary nuclear RNA transcript (PT), processing intermediate, and mature mRNA in the nucleus and the levels of the POMC mRNA in the cytoplasm after treatment of AtT20 cells with 5-15 mM concentrations of ethanol. After 15 mM ethanol for 60 to 120 min, the POMC PT levels were significantly decreased. This decreased POMC gene transcription activity was coupled with a significant reduction of the POMC cytoplasmic mRNA levels. After ethanol for 4h, however, both the decreases were no longer observed. After 8h, a decrease in the ACTH secretion in the medium was found. We further investigated if CRH or glutamate modulates the effects of ethanol on the POMC gene transcription activity. CRH at 10nM after 60 min increased the POMC PT levels, and 15mM ethanol attenuated the effect of CRH on the nuclear transcription activity. Glutamate receptor proteins, including NMDA receptor subtype NR1 (but not NR2A or NR2B) and GluR2, were identified by Western immunoblot analysis in AtT20 cells, with similar sizes to those in mouse hypothalamus. The inhibitory effect of 60 min ethanol at 5 to 15 mM on the POMC PT levels was attenuated by 50 μM L-glutamate. Together, our data showed that: (1) ethanol treatment in intoxicate doses significantly inhibited POMC gene transcription activity in a dose- and time-dependent manner in AtT20 cells, and (2) the POMC gene transcription activity in response to CRH or glutamate was altered by ethanol. Our results suggest that ethanol has an inhibitory effect on the POMC gene transcription activity in the anterior pituitary corticotrope, which may contribute to the persistent decrease in pituitary activation after chronic ethanol exposure.

Alcohol dependence and free-choice drinking in mice

Alcohol dependence continues to be an important health concern and animal models are critical to furthering our understanding of this complex disease. A hallmark feature of alcoholism is a significant increase in alcohol drinking over time. While several different animal models of excessive alcohol (ethanol) drinking exist for mice and rats, a growing number of laboratories are using a model that combines chronic ethanol exposure procedures with voluntary ethanol drinking with mice as experimental subjects. Primarily, these studies use a chronic intermittent ethanol (CIE) exposure pattern to render mice dependent and a 2-h limited access procedure to evaluate drinking behavior. Compared to non-dependent mice that also drink ethanol, the ethanol-dependent mice demonstrate significant increases in voluntary ethanol drinking. The increased drinking significantly elevates blood and brain ethanol concentrations compared to the non-dependent control mice. Studies report that the increased drinking by dependent mice is driven by neuroadaptations in glutamatergic and corticotropin-releasing factor signaling in different brain regions known to be involved in alcohol-related behaviors. The dysregulation of these systems parallels findings in human alcoholics and treatments that demonstrate efficacy in alcoholics can also reduce drinking in this model. Moreover, preclinical findings have informed the development of human clinical trials, further highlighting the translational potential of the model. As a result of these features, the CIE exposure and free-choice drinking model is becoming more widely used and promises to provide more insight into mechanisms of excessive drinking that may be important for developing treatments for human alcoholics. The salient features and possible future considerations for CIE exposure and free-choice drinking in mice are discussed.

Alcohol administration attenuates hypothalamic-pituitary-adrenal (HPA) activity in healthy men at low genetic risk for alcoholism, but not in high-risk subjects

Acute alcohol challenge studies in rodents and naturalistic observations in drinking alcoholics suggest that alcohol stimulates the hypothalamic-pituitary-adrenal (HPA) system. The literature on respective studies in healthy volunteers is more inconsistent, suggesting differential alcohol effects depending on dosage, recent drinking history, family history of alcoholism and alcohol-induced side effects. These papers and the putative pharmacologic mechanisms underlying alcohol effects on the HPA system are reviewed here and compared with a new study, in which we investigated how secretion of adrenocorticotrophin (ACTH) and cortisol is affected by ingestion of 0.6 g/kg ethanol in 33 young healthy socially drinking males with a paternal history of alcoholism (PHP) versus 30 family history negative (FHN) males. Alcohol and placebo were administered in a 2-day, double-blind, placebo controlled crossover design with randomized administration sequence. After administration of placebo, ACTH and cortisol decreased steadily over 130 minutes. In FHN subjects, secretion of both hormones was even more attenuated after alcohol, resulting in significantly lower levels compared with placebo. In PHP subjects, no alcohol effect on hormone secretion could be detected. The ratio of cortisol to ACTH secretion, each expressed as area under the secretion curve, was significantly increased by alcohol in FHN and PHP participants. These results argue against HPA stimulation being a mechanism that promotes the transition from moderate to dependent drinking. The fact that alcohol-induced HPA suppression was not detected in PHP males is consistent with the general concept that subjects at high risk for alcoholism exhibit less-pronounced alcohol effects.

Mifepristone pretreatment reduces ethanol withdrawal severity in vivo

BACKGROUND

Prolonged ethanol (EtOH) intake may perturb function of the hypothalamic-pituitary-adrenal axis in a manner that promotes dependence and influences EtOH withdrawal severity. Prior in vivo and in vitro studies suggest that corticosteroids, in particular, may be elevated during EtOH intoxication and withdrawal, suggesting that intracellular glucocorticoid receptors (GRs) may promote the development of EtOH dependence.

METHODS

Adult male Sprague-Dawley rats were subjected to a 4-day binge-like EtOH administration regimen (3 to 5 g/kg/i.g. every 8 hours designed to produce peak blood EtOH levels (BELs) of <300 mg/dl). Subgroups of animals received s.c. injection of the GR antagonist mifepristone (20 or 40 mg/kg in peanut oil at 0800 hours on each of the 4 days prior to withdrawal). BELs were assessed at 0900 and 1500 hours on Days 2 (D2) and 4 (D4) of the regimen. BEL, blood corticosterone levels (BCLs), and EtOH withdrawal-associated behavioral abnormalities were assessed 10 to 12 hours after the final EtOH administration.

RESULTS

Daily mean EtOH doses for D1 to D4 of the regimen were 14.4, 9.9, 7.1, and 8.6 g/kg, respectively. The EtOH gavage regimen produced mean BELs of 255 mg/dl at 0900 on D2 and 156.2 mg/dl at 0900 on D4 of the regimen. Withdrawal from the EtOH exposure regimen, beginning 10 hours after the last EtOH administration, produced significant elevations in BCL and behavioral abnormalities including tremors, stereotypy, and "wet dog shakes." Mifepristone administration did not alter food intake or weight during the 4-day regimen, nor were there drug-dependent differences in BEL or BCL on withdrawal day. Although mifepristone produced no significant changes in behavior of EtOH-naïve animals, pretreatment with mifepristone (40 mg/kg) significantly reduced the severity of EtOH withdrawal.

CONCLUSIONS

Findings suggest that activation of GRs promotes neuroadaptation to binge-like EtOH exposure, contributing to the development of EtOH dependence. Further, GRs may represent therapeutic targets to be exploited in reducing the severity of EtOH withdrawal.

Adolescent alcohol exposure alters the rat adult hypothalamic-pituitary-adrenal axis responsiveness in a sex-specific manner

Exposure to alcohol during adolescence exerts long-term effects on the adult brain stress circuits, causing many changes that persist into adulthood. Here we examined the consequences of adolescent intermittent ethanol (AIE, administered from postnatal day (PND) 28-42) on the hypothalamic-pituitary-adrenal (HPA) axis-related brain circuitry of rats challenged with intragastric (ig) administration of alcohol in adulthood (PND 70-71). Both male and female adolescent rats were exposed to alcohol vapors, while controls did not receive the drug, to assess whether AIE alters adult alcohol response in a sex-specific manner. We demonstrated that AIE increased paraventricular nucleus (PVN) Avp mRNA levels during late (PND 42) but not middle (PND 36) adolescence in males. While an alcohol challenge administered to 70-71-day-old rats increased Crf mRNA levels in males and Avp mRNA levels in females, AIE blunted both effects. These results suggest that AIE produced long-lasting changes in the responsiveness of the HPA axis to a subsequent alcohol challenge in a sex-specific manner. Furthermore, AIE altered adrenergic brain stem nuclei involved in stress responses in adulthood, resulting in increased numbers of phenylethanolamine N-methyltransferase (PNMT) neurons in male C2 and female C1 regions. This tended to enhance activation of the male C2 nucleus upon alcohol challenge. Collectively, these results suggest that AIE exerts long-term effects on the ability of the PVN to respond to an alcohol challenge in adulthood, possibly mediated by catecholaminergic input from the brain stem to the PVN.

HPA-axis activity in alcoholism: examples for a gene-environment interaction

Genetic and environmental influences are both known to be causal factors in the development and maintenance of substance abuse disorders. This review aims to focus on the contributions of genetic and environmental research to the understanding of alcoholism and how gene-environment interactions result in a variety of addiction phenotypes. Gene-environment interactions have been reviewed by focusing on one of the most relevant environmental risk factors for alcoholism, stress. This is examined in more detail by reviewing the functioning of the hypothalamic-pituitary-adrenal (HPA) axis and its genetic and molecular components in this disorder. Recent evidence from animal and human studies have shown that the effects of stress on alcohol drinking are mediated by core HPA axis genes and are associated with genetic variations in those genes. The findings of the studies discussed here suggest that the collaborations of neuroscience, psychobiology and molecular genetics provide a promising framework to elucidate the exact mechanisms of gene-environment interactions as seen to convene upon the HPA axis and effect phenotypes of addiction.

Cortisol awakening response in abstinent alcohol-dependent patients as a marker of HPA-axis dysfunction

Hypothalamo-pituitary-adrenocorticoid (HPA)-axis reactivity to psychosocial or pharmacological stimulants is diminished in alcohol-dependent patients during early abstinence but recovers after several months of abstention. In order to assess the physiological reactivity in the morning we used the cortisol awakening response (CAR) in saliva to compare 24 early abstainers (mean 21.9+/-7.6, range 10-36 days) with 12 alcohol-dependent patients with longer abstention periods (mean 116.8+/-45.7, range 59-230 days) and looked for an association with sleep, especially rapid eye movement (REM) sleep of the preceding night. Both groups did not differ with respect to age, duration of alcohol dependence, daily drinking dosage before detoxification, body mass index, depressivity, level of anxiety, daily cigarette consumption or sleep quality during the preceding 14 days. Sleep in the night before cortisol assessment did not differ with respect to total sleep time (412.4+/-35.9 vs. 407.0+/-38.7 min). Immediately upon awakening and 15, 30, 45 and 60 min later, specimens of salivary cortisol were collected. While starting from equal levels upon awakening longer abstaining patients with alcohol dependence showed a stronger CAR (ANOVA with repeated measurement, time x group effect: F=4.33, p<0.01) with distinctly higher cortisol levels 45 and 60 min after awakening (T=3.79, p<0.001 and T=3.06, p<0.005, respectively). Across both groups the time spent in REM-sleep only correlated with cortisol levels upon awakening (r=0.33, p<0.05). Our data indicate that CAR is a useful tool for investigating alterations in the HPA-axis regulation in abstaining alcohol-dependent patients.

Adrenocorticotropic Hormone/Cortisol Response to Physical Exercise in Abstinent Alcoholic Patients

BACKGROUND

Alterations in the hypothalamic-pituitary-adrenal (HPA) axis in alcoholic patients have been reported in various experimental conditions.

METHODS

To establish whether alcoholism affects the HPA axis activation during physical exercise, 10 recent abstinent alcoholic patients (age range: 33-45 years; duration of alcohol dependence: range 4-6 years) were tested by exercising on a bicycle ergometer. Ten age-matched healthy nonalcoholic men participated as controls. The workload was gradually increased at 3-minute intervals until exhaustion and lasted about 15 minutes for all subjects. Alcoholic patients were tested at 3 time points, at 4, 6, and 8 weeks after alcohol withdrawal, whereas controls were tested only once. Main outcome measurements were circulating levels of adrenocorticotropic hormone (ACTH) and cortisol and physiological variables during physical exercise [heart rate, blood pressure, ventilation, frequency of breathing, tidal volume, oxygen consumption (VO2), carbon oxide production (VCO2), and respiratory exchange ratio (R)].

RESULTS

Similar basal and exercise-induced changes in physiological variables were observed in controls and alcoholic patients in all tests. Basal levels of ACTH and cortisol were similar in all tests performed on alcoholic patients and on normal controls. In normal subjects, exercise induced a significant increase in plasma ACTH and serum cortisol levels, with peak levels at 20 minutes for ACTH (84% higher than baseline) and at 30 minutes for cortisol (70% higher than baseline). After 4 weeks of abstinence, slight but not significant ACTH/cortisol responses to physical exercise were observed in alcoholic patients (mean peaks were 10 and 18% higher than baseline, respectively, for ACTH and cortisol). By contrast, when the exercise test was repeated after 6 weeks abstinence, ACTH/cortisol levels rose significantly versus baseline (mean peak levels of ACTH and cortisol were 48 and 38% higher than baseline, respectively, for ACTH and cortisol). However, the hormonal responses were significantly lower than in the normal controls. At 8 weeks of abstinence, ACTH/cortisol responses were significantly higher than 2 weeks previously, and were not distinguishable from the increments observed in the normal controls (76 and 68% higher than baseline, respectively, for ACTH and cortisol).

CONCLUSIONS

In concurrence with previous reports showing alterations of the HPA axis in the central nervous system in alcohol-dependent subjects, these data show a defect of the neuroendocrine mechanism(s) underlying the ACTH/cortisol response to physical exercise for at least a month after alcohol withdrawal, with reconstitution of a normal hormonal response at 8 weeks.

Cortisol concentrations, stress-coping styles after withdrawal and long-term abstinence in alcohol dependence

Alcohol-dependent patients face a substantial risk of relapse after detoxification. A major risk factor for relapse is stress which is reflected biologically by various physiological changes that include an activation of the hypothalamic-pituitary-adrenal (HPA) axis and release of glucocorticoids. The prospective study examined cortisol concentrations and stress-coping styles in relation to abstinence 1 year following discharge from treatment. Cortisol concentrations were measured in the plasma of 46 alcohol-dependent patients (12 women) on initial presentation for treatment (day 1), and again in plasma and in cerebrospinal fluid (CSF) after 6 weeks of abstinence (day 40). These results were compared with those of 26 age- and sex-matched, healthy control subjects. After withdrawal, the patients completed a comprehensive baseline assessment including a stress-coping questionnaire (Stressverarbeitungsfragebogen SVF120) and were monitored for 1 year after discharge. Negative stress-coping styles (e.g. flight, resignation) positively correlated with higher cortisol concentration in plasma and in CSF after withdrawal (day 40). Compared with relapsers after 1 year, abstainers had significantly lower levels for cortisol in CSF, whereas the stress-coping styles did not differ between abstainers and relapsers in this sample. These findings suggest that relatively stable personality traits like stress-coping styles have no measurable influence on abstinence. The lower cortisol concentration in CSF as an indicator for HPA axis functioning is associated with long-term abstinence in detoxified alcoholics.

Endocrine alterations during a detoxification treatment with carbamazepine in male alcoholics

This study aimed to evaluate the prevalence and time-course of endocrine alterations in male alcohol addicts during a detoxification treatment and to examine a possible relation between endocrine alterations and depressive symptoms and overall mental distress. Blood samples were drawn in 54 male alcohol addicts on admission, at day 7 of treatment and at day 14 on discharge. Endocrine analysis was performed for cortisol, luteinizing hormone, prolactin, androgens, free testosterone and 17beta-estradiol. Psychometric measures (Beck's depression inventory and the symptom checklist-90-R) were taken on admission and on discharge and were correlated with endocrine measures. Cortisol plasma levels were substantially increased at the beginning of the detoxification, whereas all other endocrine parameters were within the normal range. Although subjects depicted mild to moderate levels of depressive symptoms and mental distress, there were no correlations with endocrine variables. Further analysis revealed a high variation in sex steroid levels with approximately 55% of participants showing initial (n = 19) or developing (n = 11) hypogonadal values during detoxification. In conclusion, chronic alcohol consumption induces disturbances of gonadal function which are reversible in the majority of cases. However, few patients develop a hypogonadal state during detoxification. Initially increased cortisol levels indicate a bodily stress response with the onset of alcohol withdrawal but are not related to mental disturbances.

Dissection of hypothalamic-pituitary-adrenal axis pathology in 1-month-abstinent alcohol-dependent men, part 2: response to ovine corticotropin-releasing factor and naloxone

BACKGROUND

Pituitary and adrenal responsiveness is suppressed in abstinent alcohol-dependent individuals. To clarify the specific organizational disruption in hypothalamic-pituitary-adrenal functioning during early abstinence, the authors separately assessed each level of the stress-response axis. In this second of a two-part study, ovine corticotropin-releasing factor (oCRH) was used to stimulate the pituitary corticotrophs, and naloxone was used to activate the axis at the hypothalamic level. In addition, pulsatile characteristics of corticotropin and cortisol were assessed over a 12-hr period (0800 to 2000 hr).

METHODS

Eleven abstinent alcohol-dependent men and 10 healthy comparison participants were assessed. All participants were between the ages of 30 and 50 years, and alcohol-dependent patients were abstinent from 4 to 6 weeks. Basal concentrations of corticotropin and cortisol were obtained every 10 min from 0800 to 2000 hr and subjected to pulsatile analysis. Plasma corticotropin and cortisol concentrations were then obtained every 5 to 10 min after low-dose, intravenously administered doses of oCRH (0.4 microg/kg) or naloxone (0.125 mg/kg). Medications were administered at 2000 hr and the two challenge studies were separated by 48 hr.

RESULTS

Pulsatile analysis revealed that the mean corticotropin amplitude was increased in alcohol-dependent patients relative to controls (p <0.05). Other pulsatile characteristics of corticotropin and all cortisol pulsatile measures were not significantly different between the two groups. The integrated cortisol response to oCRH was significantly lower in alcohol-dependent patients compared with controls (p <0.01), but the integrated corticotropin response was not significantly different. In contrast, neither the corticotropin nor the cortisol response to naloxone was significantly different between groups.

CONCLUSIONS

Adrenocorticoid hyposensitivity persists after oCRH infusion for at least 1 month after cessation of drinking, whereas hyporesponsiveness of the pituitary corticotrophs to CRH seems to resolve with continued abstinence. The authors suggest that adrenocortical hyporesponsiveness during prolonged abstinence may impact relapse risk.

ENDOCRINOLOGY OF THE STRESS RESPONSE

The stress response is subserved by the stress system, which is located both in the central nervous system and the periphery. The principal effectors of the stress system include corticotropin-releasing hormone (CRH); arginine vasopressin; the proopiomelanocortin-derived peptides alpha-melanocyte-stimulating hormone and beta-endorphin, the glucocorticoids; and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks, and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development and may account for a number of endocrine, metabolic, autoimmune, and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors, and the timing of the stressful events, given that prenatal life, infancy, childhood, and adolescence are critical periods characterized by increased vulnerability to stressors.

Corticotropin-releasing factor overexpression decreases ethanol drinking and increases sensitivity to the sedative effects of ethanol

RATIONALE

Corticotropin-releasing factor (CRF) may play a significant role in drug and alcohol abuse.

OBJECTIVE

To evaluate the role of CRF in these processes, we examined several ethanol (EtOH) related behaviors in mice that carry a transgene that causes overexpression of CRF.

METHODS

We examined voluntary EtOH drinking, loss of the righting reflex (LORR), EtOH-induced conditioned taste aversion (CTA), and EtOH clearance in littermate transgenic (TG) and non-transgenic (non-TG) mice. In addition, because preliminary results indicated that age exacerbated differences in EtOH consumption between the two genotypes, we performed a cross-sectional and longitudinal evaluation of this trait at two ages ( approximately 100 and 200 days old).

RESULTS

We found that TG mice consumed significantly less EtOH and had a lower preference for EtOH-containing solutions compared with their non-TG littermates. We also found that the older drug-naive TG mice drank less EtOH as compared with the younger mice of the same genotype; however, the same relationship did not exist for drug-naive non-TG mice. Prior experience in drinking EtOH when 100 days old led to decreased EtOH drinking when 200 days old in both genotypes. Duration of LORR was longer in the TG mice, EtOH-induced CTA was marginally greater in non-TG mice at the highest dose tested, and there were significant but small differences in EtOH clearance parameters.

CONCLUSIONS

These data show that CRF overexpressing mice voluntarily consume less EtOH. This difference is associated with greater sensitivity to the sedative-hypnotic effects of EtOH, but not with increased sensitivity to the aversive effects of EtOH.

Endocrine response to surgical stress and postoperative confusion in depressed patients with alcohol abuse

Both alcohol drinking and depression are risk factors for postoperative confusion and are associated with alteration of pituitary-adrenal function. We investigated the incidence of postoperative confusion, plasma cortisol and ACTH response to surgical stress in depressed patients with alcohol abuse. We studied sixty depressed patients with and without alcohol abuse who underwent abdominal surgery. Postoperative confusion occurred in 4 of 30 patients (13%) in depressed patients without alcohol abuse, 10 of 30 patients (33%) in depressed patients with alcohol abuse. Plasma cortisol concentrations (27.2 +/- 7.0, 28.3 +/- 8.2, 29.2 +/- 4.1, 28.0 +/- 6.3 and 27.9 +/- 5.7 microg dl(-1)) 15, 60 min after the skin incision, 60 min after the end of surgery, the next day and the third day after surgery in depressed patients with alcohol abuse were significantly higher than that (20.1 +/- 6.4, 21.7 +/- 9.6, 22.3 +/- 8.0, 21.9 +/- 6.7 and 20.3 +/- 5.4 microg dl(-1)) in depressed patients without alcohol abuse. In depressed patients with alcohol abuse, plasma cortisol concentrations (34.9 +/- 7.1, 33.2 +/- 5.8 and 33.4 +/- 5.5 microg dl(-1)) 60 min after the end of surgery, the next day and third day after surgery in postoperatively confused depressed patients were significantly higher than those (26.4 +/- 6.3, 25.4 +/- 5.0 and 25.2 +/- 4.9 microg dl(-1)) of nonconfused depressed patients. In conclusion, the incidence of postoperative confusion was significantly higher in depressed patients with alcohol abuse than in depressed patients without alcohol abuse. Increased plasma cortisol concentrations after surgery were associated with postoperative confusion in depressed patients with alcohol abuse.

Decreased proopiomelanocortin mRNA in lymphocytes of chronic alcoholics after intravenous human corticotropin releasing factor injection

BACKGROUND

Alcohol abuse may involve an altered neuroendocrine response that mediates lymphocyte-derived proopiomelanocortin (POMC) production and inflammation. We investigated POMC messenger RNA (mRNA) expression in human lymphocytes ex vivo and their relation to plasma ACTH and immunoreactive beta-endorphin (IR-beta-EP) after intravenous injection of human corticotropin releasing factor (hCRF) in chronic alcoholics (n = 12) and nonalcoholics (n = 12) before surgery. Lipopolysaccharide-stimulated interleukin (IL)-1 receptor antagonist (IL-1 Ra) as a marker for chronic inflammation was determined.

METHODS

Chronic alcohol abuse was diagnosed according to DSM-IV criteria and alcohol consumption >60 g/day. A reverse transcription-polymerase chain reaction method with total RNA and subsequent solid phase minisequencing was used to quantify lymphocytic POMC mRNA after intravenous hCRF injection. Plasma ACTH, cortisol, and lipopolysaccharide-stimulated IL-1 Ra of monocytes were measured by enzyme-linked immunosorbent assay, and plasma IR-beta-EP was measured by using radioimmunoassay.

RESULTS

Baseline values of POMC mRNA content in lymphocytes and IL-1 Ra of chronic alcoholics were significantly increased compared with nonalcoholics (p < 0.01). Thirty minutes after intravenous hCRF injection, a significant increase of lymphocytic POMC mRNA was measured (p < 0.05) in nonalcoholics, whereas in chronic alcoholics a significant decrease was observed (p < 0.05).

CONCLUSIONS

Chronic alcoholic patients had an altered neuroendocrine immune axis before intravenous hCRF administration and were not able to adjust to intravenous CRF injection by increasing lymphocytic POMC mRNA expression.

Increased salivary cortisol concentrations during chronic alcohol intoxication in a naturalistic clinical sample of men

BACKGROUND

Cortisol, the primary glucocorticoid in humans, is intimately involved in the regulation of such varied and critical biological processes as emotion, cognition, reward, immune functioning, and energy utilization. A persistent increase in cortisol concentration as a result of chronic intoxication could therefore result in alcohol-related disorders such as sleep disruption, cognitive deficits, diabetes, and mood disturbances. Although moderate levels of acute alcohol ingestion are reported to produce an increase in cortisol levels, it is uncertain whether cortisol remains persistently increased during long-term chronic intoxication.

METHODS

Salivary cortisol and breath alcohol concentrations (BAC) were obtained on 73 subjects with primary alcohol dependence on initial presentation for treatment and 22 alcohol-dependent subjects participating in a residential treatment program.

RESULTS

Both intoxicated alcohol-dependent subjects (n = 38) and nonintoxicated subjects in acute alcohol withdrawal (n = 30) demonstrated significantly increased salivary cortisol concentrations compared with abstinent subjects (n = 27; p < 0.001). Nonintoxicated subjects in acute withdrawal demonstrated significantly increased salivary cortisol concentrations compared with highly intoxicated subjects (BAC >100 mg/dl) but were similar to subjects with lower levels of intoxication (BAC, 10-100 mg/dl).

CONCLUSIONS

Chronic alcohol-dependent subjects experience continuously increased concentrations of cortisol during both intoxication and withdrawal. Increased levels of cortisol during chronic intoxication seem to progressively increase with the onset of withdrawal. This suggests a daily cycle of hypercortisolemia during the active drinking phase, with further increases on the cessation of drinking and the emergence of withdrawal symptoms. Persistently increased levels of cortisol may extract a costly allostatic load, resulting in significant central nervous system and peripheral organ morbidity.

Pediatric stress: hormonal mediators and human development

Stress activates the central and peripheral components of the stress system, i.e., the hypothalamic-pituitary-adrenal (HPA) axis and the arousal/sympathetic system. The principal effectors of the stress system are corticotropin-releasing hormone (CRH), arginine vasopressin, the proopiomelanocortin-derived peptides alpha-melanocyte-stimulating hormone and beta-endorphin, the glucocorticoids, and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development, and may account for a number of endocrine, metabolic, autoimmune and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors and the timing of the stressful event(s), given that prenatal life, infancy, childhood and adolescence are critical periods characterized by increased vulnerability to stressors. The developing brain undergoes rapid growth and is characterized by high turnover of neuronal connections during the prenatal and early postnatal life. These processes and, hence, brain plasticity, slow down during childhood and puberty, and plateau in young adulthood. Hormonal actions in early life, and to a much lesser extent later, can be organizational, i.e., can have effects that last for long periods of time, often for the entire life of the individual. Hormones of the stress system and sex steroids have such effects, which influence the behavior and certain physiologic functions of individuals for life. Exposure of the developing brain to severe and/or prolonged stress may result in hyperactivity/hyperreactivity of the stress system, with resultant amygdala hyperfunction (fear reaction), decreased activity of the hippocampus (defective glucocorticoid-negative feedback, cognition), and the mesocorticolimbic dopaminergic system (dysthymia, novelty-seeking, addictive behaviors), hyperactivation of the HPA axis (hypercortisolism), suppression of reproductive, growth, thyroid and immune functions, and changes in pain perception. These changes may be accompanied by abnormal childhood, adolescent and adult behaviors, including excessive fear ('inhibited child syndrome') and addictive behaviors, dysthymia and/or depression, and gradual development of components of the metabolic syndrome X, including visceral obesity and essential hypertension. Prenatal stress exerted during the period of sexual differentiation may be accompanied by impairment of this process with behavioral and/or somatic sequelae. The vulnerability of individuals to develop varying degrees and/or components of the above life-long syndrome is defined by as yet unidentified genetic factors, which account for up to 60% of the variance. CRH has marked kindling and glucocorticoids have strong consolidating properties, hence both of these hormones are crucial in development and can alone produce the above syndrome. CRH and glucocorticoids may act in synergy, as in acoustic startle, while glucocorticoids may suppress or stimulate CRH, as in the hypothalamus and amygdala, respectively. A CRH type 1 receptor antagonist, antalarmin, inhibits both the development and expression of conditioned fear in rats, and has anxiolytic properties in monkeys. Profound stressors, such as those from sexual abuse, may elicit the syndrome in older children, adolescents and adults. Most frequently, chronic dysthymia and/or depression may develop in association with gastrointestinal complaints and/or the premenstrual tension syndrome. A lesser proportion of individuals may develop the classic posttraumatic stress disorder, which is characterized by hypocortisolism and intrusive and avoidance symptoms; in younger individuals it may present as dissociative personality disorder.

Corticotropin-releasing factor testing reveals a dose-dependent difference in methadone maintained vs control subjects

Opiate addiction is associated with abnormal function of the stress-responsive hypothalamic-pituitary-adrenal (HPA) axis. In general, addiction and withdrawal are associated with abnormal HPA responsivity as demonstrated by baseline, dexamethasone, and metyrapone testing. Following stabilization in methadone maintenance treatment, normalization of HPA axis responsivity is observed. To further investigate HPA axis function associated with heroin addiction and its treatment, saline placebo and human corticotropin-releasing factor (hCRF) were administered intravenously in two doses, one dose lower (0.5 microg/kg) and one dose higher (2.0 microg/kg) than the dose used in standard clinical diagnostics (100 microg), to 16 normal male volunteer controls (NV) and eight male stable-dose methadone-maintained former heroin addicts without ongoing drug or alcohol abuse or dependence (MM). Plasma adrenocorticotrophic hormone (ACTH) and cortisol levels were determined at serial time points. There was no difference in hormonal measurements between the two groups following placebo. NV as well as MM displayed a dose-response effect in plasma ACTH and cortisol levels. MM displayed a significantly greater increase in plasma ACTH levels than the NV following high-dose but not low-dose hCRF (p <0.05). There was no significant difference in plasma cortisol levels between the two groups following high-dose hCRF. Thus, despite earlier documented normalization of behavioral function and of several measures of neuroendocrine function during long-term methadone maintenance, some abnormalities in HPA axis responsivity that may be a consequence of heroin exposure, or that may have existed prior to the addiction, can persist during stable methadone treatment.

Alcohol and withdrawal: from animal research to clinical issues

The withdrawal syndrome in alcohol-dependent patients appears to be a major stressful event whose intensity increases with repetition of detoxifications according to a kindling process. Disturbances in the balance between excitatory and inhibitory neural processes are reflected in a perturbed physical state while disturbances in the balance between positive and negative reinforcements are reflected in a perturbed mood state. Our purpose is to link the different behavioral outcomes occurring during withdrawal with specific biological brain mechanisms from the animal to the human being. Better understanding of the various biological mechanisms underlying withdrawal from alcohol will be the key to design and to apply appropriate pharmaceutical management, together with appropriate therapy aimed at inducing protracted abstinence.

Hypothalamic-pituitary-adrenal system adaptation to detoxification in alcohol-dependent patients is affected by family history of alcoholism

BACKGROUND

Alcohol withdrawal profoundly affects the hypothalamic-pituitary-adrenocortical (HPA) system. We investigated whether a family history of alcoholism modulates HPA response to pharmacologic intervention during detoxification in alcohol-dependent patients.

METHODS

Sixteen family history negative (FH-N) and 19 family history positive (FH-P) alcohol-dependent patients were admitted for withdrawal. All 35 patients were investigated 1 week after remission of withdrawal symptoms; 17 patients were also tested during acute withdrawal. Dexamethasone 1.5 mg was given orally at 11 PM, followed by 100 microg corticotropin-releasing hormone (hCRH) administered intravenously at 3 PM the following day. Plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations were determined at 0, 30, 45, 60, and 75 min after CRH.

RESULTS

During withdrawal, cortisol but not ACTH secretion was increased in patients compared with 19 control subjects matched for age and gender. After withdrawal, cortisol was normal in FH-P but still increased in FH-N patients versus control subjects, and ACTH was marginally decreased in FH-P patients only. Both hormones were increased in FH-N versus FH-P patients.

CONCLUSIONS

Recovery from alcohol withdrawal-induced impairment of HPA system regulation occurs earlier in FH-P than FH-N patients, indicating that the efficacy of central neuroadaptation to this ethanol-related stimulus may be related to genetic factors.

Psychopathology of alcoholics during withdrawal and early abstinence

Epidemiologic surveys show a high lifetime co-morbidity with psychiatric disorders (e.g., depression and anxiety) in alcoholics. However, alcoholics frequently complained about psychopathologic symptoms, particularly during alcohol withdrawal. There is some evidence that symptomatology decreases spontaneously with prolonged abstinence. Thus, the question arises whether high levels of psychopathology could be accounted for by withdrawal effects. This study was aimed at examining the impact of the alcohol withdrawal severity (assessed by the AWS scale) on psychopathologic symptoms. The psychopathologic profile of 110 alcoholics as measured by the Symptom Checklist-90 revised (SCL-90-R) was compared to that of 253 patients with adjustment, anxiety or depressive disorders (according to ICD-10 criteria). No relationship between the severity of alcohol withdrawal and psychopathology could be found which might hint at two different neurobiological processes underlying these phenomena. The comparison with patients suffering from depression or anxiety disorders revealed that the global symptom severity of alcoholics undergoing withdrawal was similar, but recovery was achieved more rapidly than in the other groups. On the other hand, the self-rated psychopathologic symptom profile of alcoholics was rather similar to that of patients with adjustment disorders. While about one-quarter of the alcoholics reported severe psychopathology on admission, only about 10% showed symptomatology at discharge about three weeks later, predominantly depression or anxiety. These results underline the notion that much of the psychopathology described by alcoholics decreases within 2-3 weeks after withdrawal without specific treatment.

Inhibition of the cortisol response to surgical stress in chronically depressed patients

STUDY OBJECTIVE

To evaluate whether the pituitary-adrenal and catecholamine response to surgical stress is modified in chronically depressed patients.

DESIGN

Prospective, controlled study.

PATIENTS

25 ASA physical status I and II depressed patients taking chronic antidepressant therapy and 25 control patients undergoing orthopedic surgery of the extremities.

INTERVENTIONS

All patients received anesthesia induction with thiopental 5 mg/kg and suxamethonium 1 mg/kg intravenously (IV) and were maintained with 1.5% to 2.0% isoflurane in nitrous oxide (70%) and oxygen (30%).

MEASUREMENTS AND MAIN RESULTS

Plasma cortisol concentration (27.7 +/- 3.6 microg/dL) in chronic depressed patients at 60 minutes after the skin incision was not significantly higher than that (23.9 +/- 2.7 microg/dL) before the induction, although plasma cortisol concentration in the control group significantly increased. Plasma norepinephrine concentration at 60 min after the skin incision in depressed patients with more symptoms of depression was significantly higher than that of patients with less symptoms of depression.

CONCLUSION

The cortisol response to surgical stress in depressed patients was inhibited and norepinephrine response to surgical stress was increased in depressed patients with more symptoms of depression.

Genetics of alcohol withdrawal

Alcohol withdrawal is a clinically and etiologically heterogeneous syndrome caused by a complex interaction of environmental (e.g., amount of ethanol) and genetic factors. Multiple genes are considered to be involved in various components of the syndrome, each of them contributing only modestly to withdrawal vulnerability. Association studies using candidate genes of the dopamine, serotonin, gabaergic and opioidergic systems are reviewed and methodological limitations are discussed.

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.

The rationale for corticotropin-releasing hormone receptor (CRH-R) antagonists to treat depression and anxiety

Neuroendocrine studies strongly suggest that dysregulation of the hypothalamic pituitary-adrenocortical (HPA) system plays a causal role in the development and course of depression. Whereas the initial mechanism resulting in HPA hyperdrive remains to be elucidated, evidence has emerged that corticosteroid receptor function is impaired in many patients with depression and in many healthy individuals at increased genetic risk for an depressive disorder. Assuming such impaired receptor function, then central secretion of CRH would be enhanced in many brain areas, which would account for a variety of depressive symptoms. As shown in rats and also in transgenic mice with impaired glucocorticoid receptor function, antidepressants enhance the signaling through corticosteroid receptors. This mechanism of action can be amplified through blocking central mechanisms that drive the HPA system. Animal experiments using antisense oligodeoxynucleotides directed against the mRNA of both CRH receptor subtypes identified the CRH1 receptor as the mediator of the anxiogenic effects of CRH. Studies in mouse mutants in which this receptor subtype had been deleted extended these findings as the animals were less anxious than wild-type mice when experimentally stressed. Thus, patients with clinical conditions that are causally related to HPA hyperactivity may profit from treatment with a CRH1 receptor antagonist.

Neuroendocrinology and pathophysiology of the stress system

The human organism is in a state of dynamic equilibrium, homeostasis. The stress system is activated when homeostasis is challenged by extrinsic or intrinsic forces, the stressors. This system, whose central component is the central nervous system (CNS) and includes corticotropin-releasing hormone (CRH) and noradrenergic neurons, respectively, in the hypothalamus and the brain stem, has as its peripheral limbs the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic (sympathetic) nervous system. Normal development and preservation of life and species are dependent on a normally functioning stress system. Maladaptive neuroendocrine responses, i.e., dysregulation of the stress system, may lead to disturbances in growth and development, and cause psychiatric, endocrine/metabolic, and/or autoimmune diseases or vulnerability to such diseases.

The effects of alcoholism on the hypothalamic-pituitary-adrenal axis: interaction with endogenous opioid peptides

BACKGROUND

Abnormal baseline hypothalamic-pituitary-adrenal axis function and dexamethasone suppressibility seen in withdrawing alcoholics returns to normal on abstinence, but some studies report blunting of the ACTH response to CRH persisting during the early abstinence phase. Reduced central levels of endogenous opioid peptides have been postulated to have an aetiological role in alcohol addiction.

AIMS

To evaluate hypothalamic-pituitary-adrenal axis function in a group of recently abstinent alcoholics using basal hormone data, naloxone (an opioid receptor antagonist), and ovine CRH.

SUBJECTS

Nine alcoholics (age 41.4 +/- 3.1 years) studied more than one week after the acute withdrawal period but within 6 weeks of cessation of drinking, and nine age and sex matched non-alcoholic controls.

PROTOCOL

Cortisol, ACTH, CRH and AVP levels were measured every 20 minutes for 2 hours between 0900 and 1100h Twenty mg naloxone i.v. was administered at 1100h (0 minutes) and further samples for the above hormones were taken at 15, 30, 45, 60, 90 and 120 minutes. On a separate occasion, again at 1100h, oCRH 1 microgram/kg (n = 7 alcoholics, n = 6 controls) was administered, with samples for cortisol, ACTH and AVP taken at the same times.

STATISTICS

Results were examined by analysis of variance for repeated measures (ANOVA), while incremental hormone response and area under the secretory curve (AUC) in alcoholics versus controls were compared by the two-tailed Student's t-test. Linear regression analysis was carried out to examine the relation between basal cortisol and hormone responses to naloxone and oCRH.

RESULTS

Basal hormone levels did not differ between the groups. The alcoholics had a blunted ACTH incremental response to naloxone (11.4 +/- 3.0 vs 21.1 +/- 2.5 pmol/l, P < 0.05) but the cortisol response was not significantly different (205 +/- 51 vs 305 +/- 42 nmol/l, P = 0.15). The alcoholics also had a blunted ACTH incremental response to oCRH (28.7 +/- 4.2 vs 41.2 +/- 3.7 pmol/l, P = 0.052) and by ANOVA a significant main effect of group (alcoholic vs control) was seen (P < 0.02) for the ACTH response to oCRH. There was no difference between the groups in the cortisol incremental response to oCRH. In the control subjects, a negative correlation was found between basal cortisol and the cortisol increment (r = -0.82, P < 0.05) and ACTH increment (r = -0.81, P = 0.052) following oCRH, while in contrast, basal cortisol correlated positively with cortisol increment (r = 0.72, P < 0.05) following naloxone. There was also a trend for basal cortisol to correlate positively with ACTH increment following naloxone in the controls (r = 0.63, P < 0.07). In the alcoholics, the normal negative effect of basal cortisol on the cortisol increment after oCRH was reversed, with a positive correlation between basal cortisol and cortisol increment (r = 0.75, P = 0.05).

CONCLUSIONS

Recently abstinent alcoholics with normal basal HPA axis hormone levels have a blunted ACTH response to naloxone and oCRH. While reduced levels of central endogenous opioid peptides may be a factor in the blunted ACTH response to naloxone in the alcoholics, it is proposed that the alcoholics have reduced pituitary responsiveness to CRH. This may be via a direct pituitary effect of the chronic ethanol exposure or by a reduction in hypothalamic-hypophyseal vasopressin levels.

Hypothalamic-pituitary-gonadal axis, prolactin, and cortisol in alcoholics during withdrawal and after three weeks of abstinence: comparison with healthy control subjects

Serum concentrations of luteinizing hormone, follicle-stimulating hormone, testosterone, androstenedione, estradiol, sex hormone-binding globulin, cortisol, and prolactin were measured in 12 male chronic alcoholics once during withdrawal and once after 21 days of abstinence. The results were compared with those of 14 healthy volunteers. During withdrawal, luteinizing hormone, estradiol, and cortisol levels were significantly enhanced. Estradiol and cortisol concentrations fell significantly during abstinence, whereas luteinizing hormone concentrations remained elevated. The results may be interpreted as follows: the well-known inhibitory effect of alcohol on the biosynthesis of testosterone may have led to a compensatory increase in luteinizing hormone secretion, so that normal serum concentrations of testosterone were maintained. On the other hand, peripheral conversion from androstenedione to estradiol via aromatase pathways seemed to be enhanced in chronic alcoholics, at least during withdrawal. Whether this marked increase in estradiol concentrations is implicated in different clinical and psychological symptoms seen in chronic alcoholics remains to be investigated.

Corticotropin-releasing factor and neuropeptide Y: role in emotional integration

The amygdala complex integrates stressful stimuli and is critical in transducing their aversive value into autonomic, endocrine and behavioural responses. Stimulation within the amygdala complex produces signs of fear without a relevant external object, while lesions in this region abolish normal fear responses. In a manner characteristic of phylogenetically old limbic brain areas, the complex neurochemical anatomy of the amygdala involves a large number of phylogenetically old peptide mediators. The distribution and connectivity of these peptide systems have been extensively studied, but less is known about their functional role. Recent evidence suggests that two neuropeptides, corticotropin-releasing factor (CRF) and neuropeptide Y (NPY) exert a reciprocal regulation of responsiveness to stressful stimuli, possibly via an interaction of these two systems in the amygdala.

Hypothalamic-pituitary function during alcohol exposure and withdrawal and cocaine exposure

This chapter examines the neuroendocrine effects of acute exposure to and withdrawal from alcohol and cocaine, with special emphasis on the hypothalamic-pituitary-adrenal (HPA) axis. We present the results from two preliminary controlled inpatient studies that document HPA dysfunction during acute exposure to alcohol and cocaine and during withdrawal from alcohol. We discuss the methodological approach of these studies in comparison to related attempts in the literature to use measures of thyroid and prolactin regulation to predict risk of relapse to alcohol and cocaine use, respectively. Our data and the results of related studies are presented in the context of a proposed index of HPA axis dysfunction that may provide a useful clinical measure of susceptibility to relapse during protracted abstinence from alcohol or cocaine.

Psychiatric implications of altered limbic-hypothalamic-pituitary-adrenocortical activity

Hormones of the limbic-hypothalamic-pituitary-adrenocortical (LHPA) system are much involved in central nervous system regulation. The major LHPA neuropeptides, corticotropin-releasing hormone (CRH), vasopressin (AVP) and corticotropin (ACTH) do not only coordinate the neuroendocrine response to stress, but also induce behavioral adaptation. Transcription and post-translational processing of these neuropeptides is regulated by corticosteroids secreted from the adrenal cortex after stimulation by ACTH and other proopiomelanocortin derived peptides. These steroids play a key role as regulators of cell development, homeostatic maintenance and adaptation to environmental challenges. They execute vitally important actions through genomic effects resulting in altered gene expression and nongenomic effects leading to altered neuronal excitability. Since excessive secretory activity of this particular neuroendocrine system is part of an acute stress response or depressive symptom pattern, there is good reason to suspect that central actions of these steroids and peptides are involved in pathophysiology determining the clinical phenotype, drug response and relapse liability. This overview summarizes the clinical neuroendocrine investigations of the author and his collaborators, while they worked at the Department of Psychiatry in Mainz. The major conclusions from this work were: (1) aberrant hormonal responses to challenges with dexamethasone, ACTH or CRH are reflecting altered brain physiology in affective illness and related disorders; (2) hormones of the LHPA axis influence also nonendocrine behavioral systems such as sleep EEG; (3) physiologically significant interactions exist between LHPA hormones, the thyroid, growth hormone, gonadal and other neuroendocrine systems; (4) hormones of the LHPA axis constitute a bidirectional link between immunoregulation and brain activity; and (5) future psychiatric research topics such as molecular genetics of affective disorders, familial risk studies, drug response analysis and neurobiology of aging will benefit from extended knowledge of neural corticosteroid effects at a clinical, cellular, and molecular level.