Auditory event-related potential abnormalities in bipolar disorder and schizophrenia

Auditory P300 latency prolongation or amplitude reduction has been reported in patients affected by bipolar disorder and in schizophrenia. The purpose of this study was to test whether the auditory P300 and earlier event-related potential (ERP) components elicited during an auditory discrimination task could differentiate between these two disorders. Thirteen patients with manic or mixed bipolar disorder, 12 patients with schizophrenia, and 24 control subjects were evaluated. None of the subjects had a history of alcohol or substance abuse or dependence. ERPs were elicited during an auditory discrimination task in which a subject pressed a key to infrequent 1500 Hz tones interspersed amid a series of 1000 Hz tones. The amplitude and latency of N100 and P200 were measured from ERPs to non-target tones, and N200 and P300 were measured from ERPs to target tones. N100, P200 and N200 amplitudes were reduced in schizophrenia patients, but not in bipolar patients. Both bipolar disorder and schizophrenia patients showed reduced P300 amplitude and prolonged P300 latency. Amplitude reduction in the early ERP components implicates auditory processing deficits in schizophrenia. Both groups showed reductions in P300 amplitude, suggesting a disturbance of the temporal-parietal generators of this component. Prolonged P300 latency is consistent with impaired attentional processing in schizophrenia and symptomatic bipolar disorder patients.

Evaluating and treating anxiety disorders in medical settings

Anxiety disorders and medical illness present to the primary care physician as a common comorbidity. This article aims to review the literature on the prevalence of anxiety disorders in patients presenting to primary care physicians; to address the key issues in assessing the comorbid condition; and to discuss psychological and pharmacological treatment options for patients with a comorbid anxiety disorder and medical illness. Anxiety disorders are highly prevalent within the primary care population, and these disorders significantly impact the patient's course and outcome. Fortunately, primary care physicians have a variety of effective cognitive, behavioral and pharmacological interventions available for managing these patients with comorbid anxiety and medical illnesses.

Role of norepinephrine in the dorsomedial hypothalamic panic response: an in vivo microdialysis study

Blockade of gamma-aminobutyric acid-A (GABA(A)) receptors in the dorsomedial hypothalamus (DMH) elicits a panic-like response that includes increases in heart rate (HR), blood pressure (BP), respiration rate (RR), and anxiety. Norepinephrine (NE) has been postulated to be critical in regulating panic and anxiety responses. Therefore, the first study sought to determine changes in extracellular NE levels within the DMH following acute blockade of GABA(A) receptors in the DMH using in vivo microdialysis. Rats were implanted with femoral arterial catheters and microdialysis probes into the DMH. Following recovery, the DMH of conscious rats were perfused with 100, 150, or 200 microM solutions of the GABA(A) receptor antagonist bicuculline methiodide (BMI) via the microdialysis probe. HR and BP responses were recorded and the changes in extracellular levels of NE in the dialysate samples from the DMH were determined by HPLC. Rats receiving BMI injections showed dose-dependent increases in both the extracellular NE levels in the DMH as well as HR and BP. The second study was conducted to test the functional importance of NE in the DMH to the BMI-induced physiological responses. The effects of BMI microinjection into the DMH were measured at baseline and 10 days after local injection of either vehicle or two doses of 6-hydroxydopamine (6-OHDA), a neurotoxin known to lesion NE terminals. There was a significant loss of tissue NE levels as well as BMI-induced HR, BP and RR responses in the 6-OHDA-treated but not vehicle-treated rats. Thus, blockade of GABA(A) receptors in the DMH results in NE release and the presence of NE appears to be necessary for eliciting the physiological components of the panic-like responses in this region.

Summary of a National Institute of Mental Health workshop: developing animal models of anxiety disorders

RATIONALE

There exists a wide range of animal models and measures designed to assess anxiety or fearfulness. However, the relationship between these models and clinical anxiety symptoms and syndromes is unclear. The National Institute of Mental Health convened a workshop to discuss the relationship between existing behavioral models of anxiety and the clinical profile of anxiety disorders. A second goal of this workshop was to outline various approaches towards modeling components of anxiety disorders.

OBJECTIVES

To briefly describe epidemiological and behavioral manifestations of clinical anxiety syndromes and how they relate to commonly employed animal models of anxiety. To describe approaches and considerations for developing, improving, and adapting anxiety models to better understand the neurobiology of anxiety.

METHODS

Clinicians, psychiatrists and clinical and basic neuroscientists presented data exemplifying different approaches towards understanding anxiety and the role of animal models. Panel members outlined what they considered to be critical issues in developing and employing animal models of anxiety.

RESULTS

This review summarizes the discussions and conclusions of the workshop including recommendations for improving upon existing models and strategies for developing novel models.

CONCLUSIONS

The probability of developing comprehensive animal models that accurately reflect the relative influences of factors contributing to anxiety disorder syndromes is quite low. However, ample opportunity remains to better define and extend existing models and behavioral measures related to specific processes that may be disrupted in anxiety disorders and to develop new models that consider the impact of combined factors in determining anxious behaviors.

Effects of ethanol on startle responding in alcohol-preferring and -non-preferring rats

The objectives of the present study were to determine (a) if differences exist between the selectively bred alcohol-preferring (P) and -non-preferring (NP) lines of rats in the acoustic startle response (ASR) and prepulse inhibition (PPI), and (b) the effects of ethanol on these measures. Alcohol-naïve adult female P and NP rats received a single i.p. injection of saline or ethanol (0.25, 0.5, 1. 0, or 1.5 g/kg) and were placed in the startle apparatus 10 min later. After a 5-min acclimation period, rats received five alternating trials of a startle stimulus alone (SSA) (115-dB white noise) or a PPI trial (90-dB white noise preceding a 115-dB white noise). Analysis of the ASR revealed that P rats exhibited higher startle amplitudes than did NP rats with saline injections. The 0. 5-g/kg ethanol dose reduced the startle amplitude in P, but not NP, rats. The 1.0- and 1.5-g/kg ethanol doses nearly abolished the ASR in the NP line, whereas only the highest ethanol dose had this effect in the P line. Vehicle-treated P and NP rats exhibited comparable PPI levels, but only P rats showed a significant disruption (30%) at the 0.50-g/kg ethanol dose. Neither P nor NP rats were affected by ethanol treatment at the 0.25-g/kg dose. Overall, the results suggest that: (a) the difference in baseline ASR may indicate line differences in the neurocircuitry mediating this response, possibly reflecting higher innate levels of emotional reactivity in the P line; (b) the P line may be more sensitive than the NP line to the effects of ethanol in reducing emotional reactivity; and (c) low-dose ethanol may have a greater disruptive effect on sensorimotor gating mechanisms in the P than NP rat.

LY354740, a potent group II metabotropic glutamate receptor agonist prevents lactate-induced panic-like response in panic-prone rats

LY354740 is a potent and selective agonist at the group II metabotropic glutamate receptors and is shown to be an effective inhibitor of glutamate release with significant anxiolytic and drug withdrawal alleviating properties in certain animal models. Rats with chronic inhibition of GABA synthesis in the dorsomedial hypothalamus (DMH) are highly anxious and exhibit panic-like responses to peripheral lactate infusions similar to patients with panic disorder. Using these panic-prone rats, we tested the efficacy of LY354740 in preventing the lactate-induced panic-like response, comparing it to alprazolam, a clinically effective anti-panic drug. Rats were fitted with femoral arterial and venous catheters and implanted with Alzet pumps infusing the GABA synthesis inhibitor L-allylglycine into the DMH. After four days of recovery, they were confirmed to be panic-prone to lactate infusions as indicated by increases in heart rate, blood pressure, respiratory rate and "anxiety" measured in the social interaction test. Next, they were pretreated with either vehicle, LY354740 (0.3 and 0.6 mg/kg) or alprazolam (0.5 and 1.0 mg/kg) and re-challenged with lactate infusions. LY354740 treatment was equally efficacious as alprazolam in preventing lactate-induced panic attacks in this model. These data suggest that LY354740 could be a novel anti-panic drug, as effective as alprazolam in acute treatment.

Sodium lactate elicits anxiety in rats after repeated GABA receptor blockade in the basolateral amygdala

Repeated administration of the GABA(A) receptor antagonist bicuculline methiodide into the basolateral nucleus of the amygdala at doses subthreshold to eliciting a full response will eventually produce long-term 'priming', such that heart rate, blood pressure as well as anxiety are increased at the lower doses. The present study was conducted in order to determine if the long-term priming of anxiety within the basolateral nucleus is producing a condition similar to that seen in human panic disorder by testing the response elicited by i.v. lactate infusions, since lactate infusions induce a panic attack in patients with panic disorder. Male Wistar rats were fitted with femoral arterial and venous catheters and chronic microinjection cannulae into the basolateral nucleus. Repeated daily injections of a subthreshold dose of bicuculline methiodide into the basolateral nucleus for 4-5 days elicited a primed response, while the same procedure with artificial cerebrospinal fluid vehicle (a-CSF; sham-primed) had no effect. Following priming, rats received both sodium lactate infusions (0.5 N, 10 ml/kg) or 0.9% saline in a random order separated by 48 h. Heart rate and blood pressure were monitored throughout the infusion and the animals were immediately placed in the social interaction test to assess their anxiety response. Only primed and not sham-primed rats responded to a lactate infusion with significant increases in heart rate, blood pressure and experimental anxiety. Thus, rats which are primed with chronic subthreshold GABA receptor blockade in the basolateral nucleus develop a sensitivity to sodium lactate, similar to human panic disorder patients.

Acoustic startle and fear-potentiated startle in alcohol-preferring (P) and -nonpreferring (NP) lines of rats

The objective of the present study was to determine whether alcohol-preferring P and -nonpreferring NP rats differ in their acoustic startle response and in fear-potentiated startle. In Experiment 1, male P and NP rats were tested on the startle response to acoustic stimuli ranging from 90-115 dB. Experiments 2 and 3 examined fear-potentiated startle and extinction of the response. In Experiment 2, rats received two light foot shock training sessions separated by 3-4 h. Testing consisted of ten acoustic startle (115 dB) and fear-potentiated startle (light preceding the acoustic startle) presentations administered every 24 h for 9 consecutive days. To test potentiated startle learning under reduced training conditions, a single training session was administered in Experiment 3, and a single within-session extinction test of 50 startle and 50 potentiated startle trials occurred the following day. Results of Experiment 1 indicated that P and NP rats did not differ in startle at any of the acoustic intensities tested. Following fear-potentiated startle conditioning in Experiment 2, however, both acoustic startle and potentiated startle responding were consistently greater in P than NP rats over most of the first 6 test days with P rats having approximately a 100% greater acoustic startle and 50-100% greater potentiated startle response. Moreover, following a single training session in Experiment 3, only P rats showed significant fear-conditioned startle. Additionally, P rats exhibited a 50-100% elevated acoustic startle response over that observed in NP rats. Taken together, the data indicate that, although experimentally naive male P and NP rats show similar acoustic startle responses, P rats become more responsive to both startle-alone and potentiated startle stimuli following fear conditioning. The change in general startle reactivity of the P rat following aversive conditioning, along with facilitated light foot shock learning, suggests that stress exposure may be an important variable in examining associations between anxiety and alcohol drinking behavior.

Role of corticotropin-releasing factor and urocortin within the basolateral amygdala of rats in anxiety and panic responses

The amygdala is a critical temporal lobe structure involved in the expression of anxiety and stress responses. The basolateral nucleus (BLA) of the amygdala in particular, may play a key role in anxiety. Furthermore, corticotropin-releasing factor (CRF), a 41 amino acid peptide, has been strongly implicated in the regulation of stress and anxiety responses. Centrally administered CRF has been shown to increase the anxiety-like behaviors of rodents in several animal models. A recently cloned related peptide, Urocortin (Ucn), appears to have similar affinity for the CRF1 receptor, but higher affinity at the CRF2 receptor. When microinjected into the BLA, we found Ucn was substantially more potent than CRF in producing anxiogenic-like behavior as assessed in the social interaction test. Furthermore, repetitive administration of subthreshold doses of Ucn and CRF resulted in 'priming'. Once primed, these animals exhibited behavioral and cardiovascular responses to intravenous sodium lactate, a panicogenic agent in susceptible human patients. These results suggest central CRF and Ucn play a role in generating anxiety which may be similar to that seen in pathological conditions such as panic disorder.

Chorioamniotic separation after second-trimester genetic amniocentesis: importance and frequency

PURPOSE

To determine the frequency and importance of chorioamniotic separation (CAS) after second-trimester genetic amniocentesis.

MATERIALS AND METHODS

In part 1 of the study, ultrasonography (US) databases were reviewed for cases of CAS. In part 2, a study population of 388 women undergoing amniocentesis underwent directed US examination for assessment of CAS 15 minutes and/or 2 weeks after amniocentesis. CAS, when present, was graded. A control population consisted of 363 women undergoing amniocentesis in whom the membranes were not assessed.

RESULTS

In part 1, a review of 23,883 records revealed seven cases of complete CAS, with three deaths, two preterm deliveries, and one emergency cesarean section delivery due to fetal distress. In two of these cases, there were extremity deformities at birth. In part 2, CAS was present in 98 (25%) of 388 women at some point. There was no association between CAS and procedural variables. There was no substantial difference in morbidity between patients with and those without CAS, between patients with different grades of CAS, or between the study and control populations.

CONCLUSION

Small degrees of CAS are frequently present after amniocentesis but are not detected because the membranes are not specifically evaluated. Complete CAS is less frequent.

The circumventricular organs form a potential neural pathway for lactate sensitivity: implications for panic disorder

Patients with panic disorder experience panic attacks after intravenous sodium lactate infusions by an as yet unexplained mechanism. Lactate elicits a panic-like response in rats with chronic dysfunction of GABA neurotransmission in the dorsomedial hypothalamus (DMH). The circumventricular organs, organum vasculosum lamina terminalis (OVLT) and subfornical organ (SFO), are potential sites that could detect increases in plasma lactate levels and activate the DMH. To test this, we obtained baseline heart rate (HR) and blood pressure (BP) responses to lactate infusions in rats fit with femoral arterial and venous catheters. Next, unilateral chronic injection cannulae connected to an Alzet infusion pump filled with the GABA synthesis inhibitor L-allylglycine (L-AG) were implanted into the DMH. Another chronic injection cannula was implanted into the region of the OVLT, SFO, or an adjacent control site, the median preoptic area (MePOA). These rats were tested once again with lactate infusions after injection of either artificial cerebrospinal fluid (ACSF) or tetrodotoxin (TTX) into the CVO sites. Injecting TTX into the OVLT completely blocked the lactate-induced response, whereas TTX injections into the SFO or MePOA did not. Also, direct injections of lactate (100 or 500 nl) into the OVLT elicited robust anxiety-like responses in these rats. These results suggest that the OVLT may be the primary site that detects lactate infusions, activating an anxiety-like response in a compromised DMH, and provide the first neuroanatomical basis for lactate response in panic disorder.

Dissociative symptoms in panic disorder

The present study examined the prevalence and correlates of dissociative symptoms in patients with panic disorder and patients with other nonpanic anxiety disorders. A total of 56 patients with anxiety disorders (13 with panic disorder alone, 16 with comorbid panic and other anxiety, and 27 with other anxiety disorders) were assessed with structured clinical interviews and a battery of questionnaires. Although 69% of patients with panic disorder experienced depersonalization or derealization during their panic attacks, panic disorder patients were no more likely to experience dissociative experiences as assessed by the Dissociative Experience Scale than patients with other anxiety disorders. In the entire sample, the prevalence of dissociative experiences was very low and well within nonpathological ranges. The correlates of dissociative symptoms were severity of depression, social anxiety, and personality disorders. The implications of these findings for conceptualizing the nature of dissociative symptoms within an anxiety population are discussed.

Basilar artery response to hyperventilation in panic disorder

OBJECTIVE

The purpose of this study was to measure the response of basilar artery blood flow to hyperventilation in patients with panic disorder.

METHOD

Transcranial Doppler ultrasonography was used to measure basilar artery flow during rest and after hyperventilation in 16 patients with panic disorder and eight normal comparison subjects. The subjects rated their dizziness at each phase.

RESULTS

The patients with panic disorder demonstrated greater reduction in flow rates and greater increases in dizziness than the normal comparison subjects.

CONCLUSIONS

The greater basilar artery sensitivity to hyperventilation shown by panic disorder patients suggests a possible mechanism for the development of neurological symptoms during panic attacks.

Excitatory amino acid receptor antagonists block the cardiovascular and anxiety responses elicited by gamma-aminobutyric acidA receptor blockade in the basolateral amygdala of rats

Blockade of gamma-aminobutyric acid (GABAA) receptors in the anterior basolateral amygdala (BLA) with bicuculline methiodide results in an increase in heart rate, blood pressure and "anxiety" in rats. Glutamate receptors in the BLA are also reported to be involved in eliciting anxiety responses. The purpose of this study was to investigate the interaction between GABAergic inhibition and glutamatergic excitation in the BLA. Male Wistar rts were implanted with femoral arterial catheters and bilateral chronic microinjection cannulae into the BLA. Each animal was injected with either artificial cerebrospinal fluid (100 nl), bicuculline methiodide (10 pmol/100 nl) or bicuculline methiodide + one dose of an antagonist of either the N-methyl-D-aspartate receptor [AP5 (20 and 100 pmol) and dizocilpine (25 and 125 pmol)] or the non-N-methyl-D-aspartate ionotropic receptor [CNQX (10 and 50 pmol) and GYKI 52466 (50 and 250 pmol)]. Increases in heart rate, blood pressure and "anxiety" (as measured in the social interaction test) observed in rats after bicuculline methiodide injections into the BLA were blocked in a dose dependent manner with the concurrent injections of either N-methyl-D-aspartate or non-N-methyl-D-aspartate antagonists, suggesting that activation of both subtypes of glutamate ionotropic receptors may be necessary for the responses elicited by GABAA receptor blockade in the basolateral amygdala.

Excitatory amino acid receptors in the basolateral amygdala regulate anxiety responses in the social interaction test

Blocking GABA(A) receptors in the basolateral amygdala (BLA) elicits increases in heart rate (HR), blood pressure (BP) and anxiety responses by enhancing a glutamate mediated excitation. The present study was conducted to determine the role of the ionotropic glutamate receptors within the BLA in regulating HR, BP and experimental anxiety. Blocking basal glutamate excitation had no significant effect on HR or BP, but did elicit a significant anxiolytic-like effect.

Maltreatment, conscience functioning and dopamine beta hydroxylase in emotionally disturbed boys

OBJECTIVE

Identify associations among early maltreatment, sufficiencies, and psychopathological interferences in the domains of conscience functioning and low serum dopamine beta hydroxylase activity.

METHOD

Nineteen emotionally disturbed boys screened for maltreatment experiences were compared according to age at onset of maltreatment, enzyme activity, and their conscience functioning in the domain of moral valuation. They were also compared in conscience functions to 19 age and sex matched normal counterparts.

RESULTS

Subjects who endured maltreatment prior to 36 months had developmental delays and interferences with functioning in more conscience domains than those who were either spared such experiences or who endured maltreatment later in life. Subjects with low enzyme activity had significantly more interference with authority and peer valuation than subjects with high enzyme activity. Greater interference with valuation was associated with lower enzyme activity and more frequent abuse prior to 36 months.

CONCLUSIONS

Psychosocial sequelae of early maltreatment have been identified in the domains of conscience. An association has been established between pathological interference in the domain of moral valuation and a putative neurobiologic sequelae of early maltreatment. Implications for future research in the psychobiology of maltreatment are discussed.

Monoamines in the dorsomedial hypothalamus of rats following exposure to different tests of "anxiety"

1. Adult male Sprague-Dawley rats were subjected to the fear-potentiated startle, elevated plus-maze and social interaction tests and the levels of norepinephrine, dopamine and serotonin in the dorsomedial hypothalamus were determined by high-performance liquid chromatography. 2. Only rats subjected to the full fear potentiated startle test and not the other tests of anxiety or components (foot shocks or acoustic startle) of fear-potentiated startle showed significant increases in norepinephrine and dopamine levels after 24 hours. 3. A time course experiment specific for the norepinephrine changes in the dorsomedial hypothalamus of fear-potentiated startle rats revealed a significant increase in tissue content as compared to controls at both the 12 and 24 hour post-test time points. 4. Tyrosine hydroxylase activity in the dorsomedial hypothalamus of the fear-potentiated startle rats did not show a significant change from controls. 5. An in vitro release study found a significant decrease in potassium-stimulated release of norepinephrine in the dorsomedial hypothalamus as compared to controls at 24 hours post-test. 6. These results suggest that animals exposed to fear-potentiated startle and not other tests of "anxiety" have a change in tissue catecholamine levels and that the norepinephrine change may be the result of a decrease in release and not an increase in synthesis.

The effects of GABAA receptor blockade in the dorsomedial hypothalamic nucleus on corticotrophin (ACTH) and corticosterone secretion in male rats

Experiments were conducted to test if blockade of GABAA receptors in the dorsomedial hypothalamic nucleus (DMH) of rats, which is known to elicit cardiovascular and anxiety responses, would also elicit changes in the plasma levels of adrenocorticotrophic hormone (ACTH) and corticosterone. Male Sprague-Dawley rats were anesthetized with pentobarbital, fitted with femoral arterial catheters and implanted with microinjection cannulae into the DMH or the sites anterior to the DMH (i.e., closer to the paraventricular nucleus (PVN) of the hypothalamus). The rats were then injected with either artificial cerebrospinal fluid (aCSF; 100 nl) or the GABAA antagonist, bicuculline methiodide (BMI; 50 pmol in 100 nl) and their plasma samples obtained at 5, 30, 60, and 120 min after microinjection. Plasma ACTH and corticosterone were measured by using a radioimmunoassay. Rats injected with BMI, but not aCSF, into the DMH showed significant increases in heart rate (HR, 110 +/- 16 beats/min), blood pressure (BP; 30 +/- 4 mmHg), and plasma levels of both ACTH (64 +/- 10 pg/ml) and corticosterone (170 +/- 25 ng/ml) from baseline. BMI injections into the anterior sites closer to the PVN did not elicit significant increases in HR, BP, or plasma levels of ACTH and corticosterone. These results suggest that a tonic GABAA receptor-mediated inhibition system regulates a coordinated physiological and neuroendocrine response in the DMH and that this neuroendocrine response is not due to diffusion of BMI to the PVN of rats.

Dorsomedial hypothalamic GABA dysfunction produces physiological arousal following sodium lactate infusions

Since impairing gamma-aminobutyric acidA (GABAA) receptor-mediated inhibition in the dorsomedial hypothalamus (DMH) of rats elicits a panic-like response, experiments were conducted to test if rats with GABA dysfunction in the DMH would be vulnerable to precipitation of a panic-like response after intravenous sodium lactate infusions. Rats were implanted with unilateral infusion cannula into the DMH which were connected with Alzet minipumps that chronically infused (3.5 nmol/microliter /h) either a-CSF (vehicle), dl-(racemic), l-(active) or d-(inactive) isomers of allylglycine (AG), an inhibitor of GABA synthesis. Another group of rats had l-allylglycine pumps implanted in the paraventricular nucleus of the hypothalamus (PVN) as anatomical controls. Animals were tested in the social interaction (SI) test and given sodium lactate infusions (10 ml/kg/15 min) before Alzet pump implantations and on days 4, 7, and 14 after pump placement. Rats were also tested in the elevated plus-maze on treatment day 4. Chronic impairment of GABA function in the DMH and not PVN resulted in rats being more anxious in the SI test on treatment days 4, 7, and 14 and in the elevated plus-maze on day 4 compared to a-CSF and d-AG infusions. Further, rats with GABA dysfunction in the DMH, and not PVN, exhibited significant increases in heart rate and blood pressure following IV sodium lactate infusions. There were significant decreases in DMH glutamic acid decarboxylase activity and GABA content in rats receiving 7 days of dl-AG or l-AG infusions. These results indicate that chronic reduction of GABA function in the DMH leads to the development of panic-like disorder in this animal model.

Prevalence and correlates of anger attacks: a two site study

Although anger attacks have been described in depressed outpatients, they have not been well studied in other disorders. In Study 1, we examined the prevalence of anger attacks in 50 outpatients with panic disorder. In Study 2, we replicated the initial findings at an independent site and examined the specificity of anger attacks by comparing their occurrence in patients with panic disorder, patients with other non-panic anxiety disorders and patients with a depressive disorder. At both sites, we also explored the relationship between anger attacks and demographic and clinical characteristics, such as gender, presence and severity of depression, and social anxiety measures. In both sites, the prevalence of anger attacks in patients with panic disorder was approximately one-third. However, anger attacks were not unique to panic disorder, with similar rates emerging for patients with other anxiety disorders. Furthermore, patients with depressive diagnoses had twice the prevalence of anger attacks than did anxiety patients. At both sites, those with anger attacks were significantly more depressed and were likely to have either current or past history of major depression. Anger attacks were not associated with social anxiety measures, but were related to cluster B, cluster C and self-defeating personality disorder traits. Our findings support the notion that anger attacks are best conceptualized as an associated feature of depression.

Regulation of anxiety by GABAA receptors in the rat amygdala

Blockade of GABAergic inhibition in the region of the anterior basolateral amygdala (BLA) of rats elicits physiologic changes associated with a defense reaction. The present study was undertaken to determine whether GABA receptors in the BLA might be involved in regulating experimental anxiety using the social interaction (SI) and conflict test. Guide cannulae were stereotaxically implanted bilaterally in the BLA of rats for intracerebral microinjections. In the BLA, injection of the GABAA receptor antagonists bicuculline methiodide (BMI) and picrotoxin (PIC) produced anxiogenic-like effects in the SI paradigm, as did BMI injection using the conflict paradigm. Injection of the GABAA agonist muscimol (MUS) into the central nucleus of the amygdala (Ce) produced anxiolytic-like effects in the SI test. Microinjection of MUS, baclofen (GABAB agonist), 2OH-saclofen (GABAB antagonist) or strychnine (glycine antagonist) into the BLA or BMI into the Ce elicited no change in experimental anxiety as measured by the SI test. These results suggest that endogenous GABA acts tonically at GABAA receptors in the BLA to inhibit anxiety responses.

Priming of experimental anxiety by repeated subthreshold GABA blockade in the rat amygdala

Blockade of GABAA receptor function in the area of the anterior basolateral amygdala of rats elicits physiological (increases in heart rate and blood pressure) and behavioral changes similar to symptoms of human anxiety states. Repeated subthreshold blockade of GABAA receptors in this region appears to result in a long-term 'priming' of these anxiety-like responses. The present study was conducted to characterize the 'priming' of the heart rate and blood pressure responses and to test if these 'primed' animals would show increases in anxiety responses. Male Wistar rats with arterial catheters placed for physiological measurements were implanted with chronic microinjection cannulae in the anterior basolateral amygdaloid nucleus (BLA) under pentobarbital anesthesia. Repeated daily injections of a subthreshold dose of bicuculline methiodide (GABAA receptor antagonist; BMI) into the BLA elicited 'priming' of physiological responses after 3-5 injections and this response was maintained for at least 6 weeks. The primed animals also showed increased anxiogenic responses to GABAA blockade in the BLA. The 'priming' of anxiety responses were clearly elicited before kindling of seizures as measured by EEG. These results suggest that this 'priming' phenomenon may be similar to kindling and long-term potentiation. This could be one potential mechanism for developing pathological emotional responses, such as chronic, high levels of anxiety.

Serum dopamine beta hydroxylase and maltreatment in psychiatrically hospitalized boys

Fifty boys, hospitalized on a school-age and an adolescent unit in an intermediate length psychiatric hospital, were studied while off psychoactive medication to determine how serum dopamine beta hydroxylase (DBH) activity varies with different childhood maltreatment experiences. Childhood maltreatment was categorized according to onset (before 36 months old, between 36-72 months old and over 72 months old). Childhood maltreatment groups were compared with a group of psychiatrically hospitalized boys who had neither been abused nor neglected. Boys who were younger than 72 months at age of onset of maltreatment had significantly lower DBH activity than those who had experienced maltreatment later in childhood and those who had not been subjected to abuse or neglect. This difference appeared attributable to the DBH activity of school age (but not adolescent) boys who had been abused/neglected before 72 months. Boys with a principal diagnosis of conduct disorder solitary aggressive type had lower DBH activity than boys without this diagnosis regardless of whether or not they had been maltreated. Low serum DBH may be a biological sequela of maltreatment early in life that correlates with the development of conduct disorder solitary aggressive type in boys.