Mental health support for and telehealth use by Australians living with borderline personality disorder during the onset of the COVID-19 pandemic: A national study

Objective

To investigate mental health service use and telehealth experience of people living with BPD in Australia during the first year of the COVID-19 pandemic.

Methods

An online survey was used to collect data from people who self-identified with a diagnosis of BPD.

Results

One hundred and sixty-nine survey responses were included in the analysis. More than half of participants acknowledged receiving information from their health service about resources that they could use if they become distressed. More than 70% of participants used telehealth for receiving mental health services; the majority used telehealth to consult a psychologist or to obtain prescriptions. Telehealth sessions were conducted over the phone, via videoconferencing, or using a mix of the two. While using telehealth, some participants found it more difficult to control their impulses to self-harm, to express thoughts about self-harm and suicide, to control feelings of anger, and to establish and maintain agreed treatment boundaries. Thematic analysis of participants' experiences of telehealth identified five main themes: Communication challenges, Technology challenges, Privacy concerns, Benefits of telehealth, and Personal preferences.

Conclusion

The study findings revealed a variety of positive and negative consumer experiences. While the majority of participants found telehealth somewhat benefitted their mental health, challenges were also reported which raise concerns about the broader utility and effectiveness of telehealth.

Late manifestation of borderline personality disorder: Characterization of an under-recognized phenomenon

Although uncommon, borderline personality disorder (BPD) may manifest for the first time later in life. A retrospective clinical file audit was used to identify the clinical manifestation of BPD for the first time at or above the age of 30, and to examine whether particular clinical and psychosocial factors may be associated with a later-in-life manifestation of BPD. Twenty-three cases of late manifestation BPD were identified. People with late manifestation of BPD had similar risk factors and vulnerabilities, including childhood trauma, to the broader BPD population. They were distinguished by having higher levels of education, employment, and long-term intimate relationships. Interpersonal problems, loss of employment and reminders of past sexual trauma were key precipitating factors. The findings underscore the legitimacy of a late-manifestation diagnosis of BPD by demonstrating that BPD does not present exclusively during adolescence and early adulthood. BPD may present for the first time in later life in response to loss of protective factors or triggering of past trauma. This understanding may reduce misdiagnosis or delayed diagnosis, prescription of inappropriate treatments or delays in receiving BPD-appropriate treatments.

Emergency department utilisation by patients with a diagnosis of borderline personality disorder: An acute response to a chronic disorder

OBJECTIVE

Patients with borderline personality disorder (BPD) are likely to attend the ED while experiencing crises and associated self-injury and suicidality. Our study describes the prevalence, features, and outcomes associated with ED presentations by patients diagnosed with BPD in Outer Eastern Melbourne, Australia.

METHODS

A retrospective electronic audit of 157 364 ED attendances identified 700 unique BPD-related ED presentations between May 2015 and April 2016. For the purpose of comparison, 583 (81% female) of these 700 cases were matched with 'depression only' cases. ED re-presentation data were also extracted.

RESULTS

The 583 matched BPD patients attended ED a total of 2807 times during the audit year compared with 1092 attendances for matched depression-only patients. BPD patients were more likely to: arrive by ambulance (50%); have comorbid substance abuse (44%); have a psychotic (15%) or bipolar disorder (17%); be under the care of a psychiatrist (31%); be case-managed (42%); and be admitted to an inpatient unit (21%). ED doctors saw 38% of BPD or depression patients within the recommended time according to their triage category. The majority (73%) of BPD patients attended ED more than once during the audit year (average 4.81 ± 6.63 times; range 2-78).

CONCLUSION

Repeated ED attendance of a subset of patients diagnosed with BPD highlights both the severity of their presentation and the inadequacy of community mental health services for meeting their complex needs. Development of effective ED referral pathways with follow-up to engage patients in BPD-appropriate treatment will reduce the likelihood of crises and reliance on hospital EDs for acute episodic care.

Development and Preliminary Evaluation of a Rapid Screening Tool for Detecting Borderline Personality Disorder in People Aged over 60 Years

OBJECTIVES

Screening and diagnostic instruments for Borderline Personality Disorder (BPD) are not validated in people aged over 60. We report a pilot study examining the sensitivity and specificity of a de-novo screening instrument in older adults.

METHODS

The BPD-OA screening tool incorporates DSM 5 and literature describing the expression of BPD in older adults. This study was conducted using a case control design. The Diagnostic Interview for Borderlines-Revised (DIB-R) and the McLean Screening Instrument for BPD (MSI-BPD) were used as comparators. Comprehensive assessment by psychiatric teams determined participants to be (i) BPD-positive (n = 22) or (ii) BPD-negative (gender matched; n = 21).

RESULTS

The BPD-OA was the most sensitive instrument for discriminating older adult BPD from non-BPD participants (sensitivity = 0.82). No significant relationship was found between the BPD-OA score and age in BPD-diagnosed participants (r = -0.181, n = 21, p = .432). Participant age explained 3.2% of the variance in BPD-OA scores. Of the 21 BPD-negative participants, eight false positives experienced prominent mood disorders (specificity = 0.62).

CONCLUSIONS

The BPD-OA screening tool is clearly superior to instruments validated for use in younger people. Further refinement and evaluation will enhance its sensitivity and specificity.

CLINICAL IMPLICATIONS

Detection of BPD in older adult care settings will improve outcomes for patients, families, and staff through better understanding and appropriate management and treatment strategies.

Disjunction in the subjective and objective measurement of co-occurring depression in borderline personality disorder - Implications for diagnosis

OBJECTIVE

Research and clinical experience suggest that people with borderline personality disorder (BPD) are more likely to report greater severity of depressive symptoms than is objectively measured by their clinician. The prominence of low mood in association with BPD can result in the treatment of depressive symptoms being prioritised over the diagnosis and treatment of BPD.

METHOD

This study investigated the utility of validated clinician-administered and self-report depression rating scales during psychiatric assessment of 49 clients diagnosed with BPD.

RESULTS

Considerable discrepancies emerged between client and clinician ratings of depression, with client-rated scales generating significantly higher depression scores. Both client-rated and clinician-rated depression scores were positively influenced by the severity of BPD symptoms.

CONCLUSIONS

These findings raise questions about the interpretation of rating scales in clinical decision-making and highlight inherent uncertainty when diagnosing major depressive disorder in people who have borderline personality disorder. The accurate diagnosis of low mood has significant implications for the treatment and management of both disorders.

The impact of COVID-19 lockdown on the well-being of clients of a specialist personality disorder service

OBJECTIVE

The aim of this study was to investigate the well-being of people with severe borderline personality disorder (BPD) during the first wave of COVID-19 social restrictions.

METHOD

Clients of an outpatient specialist personality disorder clinic (n = 77) were invited to the study. An online survey was conducted including a range of open-ended questions exploring well-being and the Coronavirus Anxiety Scale (CAS) which assesses 'coronaphobia'. Qualitative data were analysed using inductive content analysis with NVivo software. CAS data were analysed descriptively using SPSS version 25.

RESULTS

Thirty-six surveys were completed (48% response rate). Many participants experienced significant challenges to their overall well-being during lockdown although some reported improvements in psychosocial functioning. Three participants (8.3%) experienced clinically significant 'coronaphobia'.

CONCLUSION

The self-reported physical and mental health of participants with BPD demonstrated resilience, suggesting that the capacity to maintain treatment via telehealth helped to mitigate many of the adverse aspects of social restrictions. This study was conducted during the first wave of social restrictions; subsequent studies will reveal longer-term effects of extended community lockdowns.

Discriminative stimulus properties of the 5-HT1A receptor biased agonists NLX-101 and F13714, in rats trained to discriminate 8-OH-DPAT from saline

NLX-101 and F13714 are selective, full efficacy, biased agonists of the serotonin (5-HT1A) receptor. NLX-101 preferentially activates cortical postsynaptic 5-HT1A receptors, whereas F13714 preferentially activates raphe nuclei presynaptic 5-HT1A receptors. We compared NLX-101 and F13714 for their efficacy and potency to substitute for the discriminative cue produced by the prototypical, nonbiased 5-HT1A receptor agonist 8-OH-DPAT (racemate). Male and female Sprague-Dawley rats were trained to discriminate 8-OH-DPAT (0.1 mg/kg i.p., 20 min pretreatment) from saline using a classical two-lever drug-discrimination procedure. 8-OH-DPAT (0.01 and 0.05 mg/kg i.p.) dose-dependently substituted for the training dose, with about 50% responding on the 8-OH-DPAT-associated lever at 0.05 mg/kg. F13714 fully and very potently substituted for the training dose of 8-OH-DPAT from 0.018 mg/kg i.p., whereas NLX-101 only achieved full substitution at 0.5 mg/kg i.p., a dose which is known to also activate presynaptic 5-HT1A receptors. The 5-HT1A receptor partial agonist, buspirone, partially substituted (~80%) at 1 and 2 mg/kg i.p., doses which also decreased response rates. F13714 decreased response rates at 0.05 mg/kg. The selective 5-HT1A receptor antagonist WAY-100 635 (1 mg/kg s.c., 40 min pretreatment) elicited almost no responding on the 8-OH-DPAT-associated lever by itself, but blocked the discriminative stimulus effects produced by administration (20 min pretreatment) of 8-OH-DPAT (0.1 mg/kg), F13714 (0.025 mg/kg), NLX-101 (0.5 mg/kg) or buspirone (1 mg/kg). These data suggest that the discriminative cue produced by 0.1 mg/kg i.p. 8-OH-DPAT results from activation of presynaptic 5-HT1A receptors. They also further demonstrate the distinct profiles in behavioral models of 5-HT1A receptor-biased agonists.

Psychotherapy via Telehealth during the COVID-19 Pandemic in Australia–Experience of Clients with a Diagnosis of Borderline Personality Disorder

OBJECTIVE: To investigate the transition to, and experience of, telehealth in people with a diagnosis of borderline personality disorder (BPD). METHOD: A cross-sectional study using an online survey was conducted in a specialist clinic for personality disorders in March-May 2020. RESULTS: Thirty-seven clients (48% response rate) completed the survey. Two participants (5.4%) were decided not to receive treatment via telehealth. Transitioning from in-person to telehealth, the majority of participants had few or no technical issues (51.4%). Telephone, video-conferencing and a mix of telephone and video-conferencing were used. Positive and negative experiences were endorsed asking about the effectiveness of telehealth. While some participants were whether unsure (32%) or not (19%) interested in telehealth following pandemic, half acknowledged the presence of telehealth (54.8%) and wanted to have the option of telehealth following pandemic (48.6%). CONCLUSIONS: Despite some shortcomings associated with telehealth, almost every client continued to attend appointments and half of the study participants wanted to have the option of telehealth in the future. Healthcare policymakers and mental health managers should consider the challenges described in this study while developing telehealth guidelines to best support people experiencing problems living with the psychiatric diagnoses of BPD.

Telehealth Psychotherapy for Severe Personality Disorder during COVID-19: Experience of Australian Clinicians

OBJECTIVE: Restrictions on social interaction during the COVID-19 pandemic necessitated a rapid transition to telehealth to continue providing psychotherapy to people diagnosed with personality disorder. This naturalistic cross-sectional study evaluated the experiences of clinicians using telehealth for the first time to treat clients diagnosed with a severe personality disorder (complex and/or high risk presentation). METHODS: Thirty clinicians working at a specialist clinic for personality disorders completed an online survey during May-June 2020 in Melbourne, Australia. RESULTS: Despite having some initial technical issues, most participants rapidly and successfully connected with clients via phone and/or video-conference, recommencing individual and group evidence-based psychotherapies. Appointments were kept more reliably than when in-person treatment was offered. Issues around privacy, confidentiality, risk, quality of interaction, and treatment boundaries were raised, highlighting the need for specific guidelines and formal processes. However, clinicians’ awareness of some of the benefits of telehealth was evident, with most looking forward to using telehealth for some aspects of their work with clients and more generally into the future. CONCLUSIONS: This experience with delivering psychotherapy using telehealth during COVID restrictions suggests that it is an acceptable platform that can be managed safely for treating patients with severe mental illness in the short term at least. This outcome encourages the pursuit of efficacy studies to evaluate telehealth as a more equitable and accessible treatment modality.

Coroners' investigations of suicide in Australia: The hidden toll of borderline personality disorder

Borderline Personality Disorder (BPD) is associated with a high risk of death by suicide. Our study describes a population-based analysis of Coroners' investigations of suicides where there was evidence of a BPD diagnosis. We utilised the Victorian Suicide Register to identify suicides occurring between 2009 and 2013 where evidence of a BPD diagnosis was recorded. Of the 2870 suicides during this period, 181 (6.3%) had a BPD diagnosis recorded. Evidence of other diagnosed personality disorders was recorded in an additional 14 (0.5%) suicides and BPD was suspected in another 72 (2.5%) suicides. Information coded in the 181 diagnosed BPD suicides was compared with the 2689 suicides without a BPD diagnosis. Compared to the 'no BPD suicide group', the 'BPD suicide group' was younger, comprised a smaller proportion of women, had greater diagnostic complexity, a higher proportion of death by drug overdose, and a higher proportion of social and contextual stressors. 99% of people with a BPD diagnosis who died from suicide had contact with emergency and mental health services within 12 months of death; 88% sought help from these services within 6 weeks of death. These findings demonstrate the magnitude of this most severe outcome of mental illness, confirming that BPD belongs in the same category as schizophrenia, bipolar disorder and depressive disorder with respect to suicide representation. The help-seeking behaviours evident in almost all cases highlight a critical window of opportunity for providing timely support and treatment to help avert future deaths.

An exploration of self-compassion and self-criticism in the context of personal recovery from borderline personality disorder

OBJECTIVES:

A lack of compassion for oneself, or harsh self-criticism, is associated with a range of psychiatric disorders including borderline personality disorder (BPD). Personal recovery in the context of a mental illness such as BPD involves building a life that is subjectively meaningful and satisfying. Limited self-compassion or harsh self-criticism may be an impediment to recovery from BPD. The association between self-compassion and recovery and self- criticism and recovery were examined.

METHOD:

Nineteen individuals diagnosed with BPD completed the Neff Self-Compassion Scale, the Forms of Self-Criticising/Attacking and Self-Reassuring Scale and the Recovery Assessment Scale at a single time point.

RESULTS:

There was a strong positive correlation between self-compassion and recovery ( r = 0.75) and a strong negative correlation ( rho = -0.67) between self- criticism and recovery.

CONCLUSIONS:

Although preliminary in nature, these results suggest the importance of fostering self-compassion and working to address self-criticism within clinical interventions supporting recovery from BPD.

Reviewing the clinical significance of 'fear of abandonment' in borderline personality disorder

OBJECTIVES:

To review and highlight the clinical significance of the symptom 'fear of abandonment' in borderline personality disorder (BPD).

METHODS:

A systematic search of the literature was conducted using MEDLINE and PubMed, employing search terms including 'fear of abandonment', 'borderline personality disorder' and 'rejection'. The most relevant English-language articles and books were selected for this review.

RESULTS:

Fear of abandonment is widely recognised as a core symptom in BPD; a biopsychosocial explanation for the occurrence of the symptom is presented. While fear of abandonment may differ in its clinical presentation, it has a significant impact on therapeutic engagement, suicidal behaviour and non-suicidal self-injury, clinical management and prognosis. Most evidence based psychotherapies for BPD address the phenomenon of fear of abandonment; however, the lack of specifically targeted treatment interventions is disproportionate to its prominence and clinical significance.

CONCLUSIONS:

Given its defining role in BPD, we recommend fear of abandonment as an important subject of future research and a specific therapy target.

What is the clinical significance of chronic emptiness in borderline personality disorder?

OBJECTIVE

The objective of this study was to review the clinical significance of the experience of chronic emptiness in borderline personality disorder (BPD).

METHODS

A systematic search of the literature was conducted using MEDLINE and PubMed, employing search terms including 'emptiness', 'personality disorder' and 'borderline personality disorder'. The most relevant English-language articles and books were selected for this review.

RESULTS

Published literature and clinical experience suggest that chronic emptiness represents a substantial component of the symptom burden experienced by people with BPD, contributes to functional impairment and may distinguish BPD from other disorders such as major depressive disorder.

CONCLUSIONS

Further research will elucidate the significance of chronic emptiness with regard to diagnosis, prognosis and treatment of BPD.

Evaluation of a novel risk assessment method for self-harm associated with Borderline Personality Disorder

OBJECTIVES

Borderline personality disorder (BPD) is associated with frequent self-harm and suicidal behaviours. This study compared physician-assessed self-harm risk and intervention choice according to a (i) standard risk assessment and (ii) BPD-specific risk assessment methods.

METHODS

Forty-five junior and senior mental health physicians were assigned to standard or BPD-specific risk training groups. The assessment utilized a BPD case vignette containing four scenarios describing high/low lethality self-harm and chronic/new patterns of self-harm behaviour. Participants chose from among four interventions, each corresponding to a risk category.

RESULTS

Standard and BPD-specific groups were alike in their assessment of self-harm risk. Divergence occurred on intervention choice for assessments of low lethality, chronic risk ( p<.01) and high lethality, chronic risk ( p<.005). Overall, psychiatrists were more likely than their junior colleagues to correctly assess risk and management options.

CONCLUSIONS

Although standard and BPD-specific methods are well aligned for assessing self harm-associated risk, BPD-specific training raised awareness of BPD-appropriate interventions, particularly in the context of chronic patterns of self-harm behaviour. Wider dissemination of BPD-specific risk training may enhance the confidence of mental health clinicians in identifying the nature of self-harm risk as well as the most clinically appropriate interventions for clients with BPD.

Evaluation of changes in prescription medication use after a residential treatment programme for borderline personality disorder

OBJECTIVE

Residential patients diagnosed with borderline personality disorder were evaluated to determine whether borderline personality disorder-focused psychotherapy reduced prescribing, personality disorder and co-morbid symptom severity.

METHOD

Psychotropic prescriptions were measured at admission, discharge and 1 year later in 74 female participants with one or more personality disorder diagnosis and co-morbid mood disorders. Changes in pharmacotherapy were examined in the context of improvements in borderline personality disorder and/or co-morbid disorder symptom severity. Residential treatment included individual and group psychotherapy for borderline personality disorder. The Structured Clinical Interview for DSM-IV was used to confirm the borderline personality disorder diagnosis and associated co-morbid conditions. The Beck Depression Inventory was completed at each time point.

RESULTS

A significant reduction in the incidence and severity of self-rated depression as well as clinician assessed personality disorder, including borderline personality disorder, was accompanied by a reduction in prescription of psychoactive medications.

CONCLUSIONS

Three to six months of intensive borderline personality disorder-specific psychotherapy showed lasting benefit with regard to symptom severity of personality disorders (borderline personality disorder in particular) as well as depressive symptoms. This improvement corresponded with a reduction in prescriptions for psychoactive medications, which is consistent with current thinking regarding treatment for borderline personality disorder.

Risky drug use and effects on sleep quality and daytime sleepiness

OBJECTIVE

Sleep problems are commonly reported following alcohol and cannabis abuse, but our understanding of sleep in non-clinical drug using populations is limited. The present study examined the sleep characteristics of alcohol and cannabis users recruited from the wider community.

METHODS

Two hundred forty-eight self-identified alcohol and/or cannabis users (131 women and 117 men) with a mean age of 26.41 years completed an online study that was advertised via online forums, print media and flyers. As part of the study, participants completed validated sleep scales assessing sleep quality (Pittsburgh Sleep Quality Index) and excessive daytime sleepiness (Epworth Sleepiness Scale) in addition to validated drug scales assessing alcohol (Alcohol Use Disorders Identification Test) and cannabis (Marijuana Screening Inventory) use.

RESULTS

Problems with sleep quality were more commonly reported than were complaints of excessive daytime sleepiness. Clinically significant poor sleep quality was associated with comorbid problem alcohol and cannabis use. Women reporting problem alcohol and cannabis use had poorer sleep outcomes than men.

CONCLUSIONS

Social drug users who report risky alcohol and cannabis use also report poor sleep. Poor sleep quality likely exacerbates any drug-associated problems in non-clinical populations.

Male and female ecstasy users: differences in patterns of use, sleep quality and mental health outcomes

BACKGROUND

Ecstasy users report a number of adverse effects following use including mood and sleep disturbances. The present study examined differences in characteristics of ecstasy use (amount, frequency of use, reported harm resulting from use) between males and females and assessed relationships between ecstasy use, sleep quality and mental health outcomes.

METHODS

An online survey of 268 ecstasy users (54.1% male, 45.9% female) was conducted. Validated sleep instruments assessing sleep quality and excessive daytime sleepiness, as well as questionnaires regarding physical and mental health (measured using the short-form health survey 12 (SF-12) and details of drug use were included.

RESULTS

Male ecstasy users reported taking larger amounts of ecstasy, but were not more frequent users compared to females. Female ecstasy users were more likely to report increased harm following ecstasy including: feelings of guilt and remorse; failing to do what was normally expected of them; and having been told by others to cut down their ecstasy use. There were interactions between amount and gender and frequency and gender in predicting use of sleep medication and daytime dysfunction. There was a positive correlation between poorer sleep quality and negative mood, although this relationship was not moderated by sex.

CONCLUSIONS

There is a significant association between sleep quality and mood disturbance in ecstasy users suggesting that these negative outcomes are co-morbid. These findings have implications for the treatment and advice given to ecstasy users who are experiencing sleep and/or mood related complaints.

Fumaroylamino-4,5-epoxymorphinans and related opioids with irreversible μ opioid receptor antagonist effects

We have previously shown that cinnamoyl derivatives of 14β-amino-17-cyclopropylmethyl-7,8-dihydronormorphinone and 7α-aminomethyl-6,14-endoethanonororipavine have pronounced pseudoirreversible μ opioid receptor (MOR) antagonism. The present communication describes the synthesis and evaluation of fumaroylamino analogues of these cinnamoylamino derivatives together with some related fumaroyl derivatives. The predominant activity of the new ligands was MOR antagonism. The fumaroylamino analogues (2a, 5a) of the pseudoirreversible antagonist cinnamoylamino morphinones and oripavines (2b, 5b) were themselves irreversible antagonists in vivo. However the fumaroylamino derivatives had significantly higher MOR efficacy than the cinnamoylamino derivatives in mouse antinociceptive tests. Comparison of 2a and 5a with the prototypic fumaroylamino opioid β-FNA (1a) shows that they have similar MOR irreversible antagonist actions but differ in the nature of their opioid receptor agonist effects; 2a is a predominant MOR agonist and 5a shows no opioid receptor selectivity, whereas the agonist effect of β-FNA is clearly κ opioid receptor (KOR) mediated.

Modulation of anxiety behavior in the elevated plus maze using peptidic oxytocin and vasopressin receptor ligands in the rat

Oxytocin (OT) and arginine vasopressin (AVP), in their capacities as neuromodulators, are believed to play an important role in mood control, including regulation of the anxiety response. In the present study, the contributions of oxytocin and vasopressin receptor modulation to anxiety-like behaviors were examined in male Sprague-Dawley rats. The behavioral effects of the OT receptor agonist, carbetocin (intracerebroventricular, intravenous and intraperitoneal routes), the AVP receptor agonist desmopressin (intravenous route), and the OT/AVP(1A) receptor antagonist atosiban (intravenous route) were evaluated in the elevated plus maze. The benzodiazepine diazepam was included as a positive control. Central but not systemic administration of carbetocin produced pronounced anxiolytic-like behavioral changes comparable to those measured following systemic diazepam treatment. The anxiolytic efficacy of carbetocin was maintained following 10 days of once-daily treatment, contrasting with the effects of diazepam which were no longer distinguishable from saline treatment. Systemic administration of desmopressin produced anxiogenic-like effects whereas systemic atosiban produced anxiolytic-like effects. Co-administration of desmopressin with atosiban resulted in saline-like behavioral responses, implicating an AVP(1A) receptor mechanism in the anxiolytic and anxiogenic effects of these neuropeptides following systemic administration. A peripherally-mediated antidiuretic effect of desmopressin on water consumption was also demonstrated. These results highlight the potential therapeutic utility of AVP(1A) receptor blockade in the modulation of anxiety-related behaviors; AVP(1A) receptor blockade appears to be a more promising pharmacological target than does OT receptor activation following systemic drug administration.

Ecstasy use and self-reported disturbances in sleep

OBJECTIVE

Ecstasy users report a number of complaints after its use including disturbed sleep. However, little is known regarding which attributes of ecstasy use are associated with sleep disturbances, which domains of sleep are affected or which factors may predict those ecstasy users likely to have poor sleep quality and/or excessive daytime sleepiness.

METHODS

This study examined questionnaire responses of social drug users (n = 395) to the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale.

RESULTS

A significant proportion of ecstasy users (69.5%) had Pittsburgh Sleep Quality Index scores above the threshold used to identify sleep disturbance. Although frequency of ecstasy use did not affect the degree of reported sleep disturbance, participants who used larger amounts of ecstasy had poorer sleep. In addition, participants who perceived harmful consequences arising from their ecstasy use or had experienced remorse following ecstasy use had poorer sleep. Clinically relevant levels of sleep disturbance were still evident after controlling for polydrug use. Risk factors for poor sleep quality were younger age, injury post-ecstasy use and having been told to cut down on ecstasy use.

CONCLUSIONS

Many ecstasy users report poor sleep quality, which likely contributes to the negative effects reported following ecstasy use.

Examining the role of oxytocin in the interoceptive effects of 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') using a drug discrimination paradigm in the rat

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') use results in distinctive mood changes of a prosocial nature, most likely through its enhancement of serotonin (5HT) neurotransmission. Activation of 5HT-1A postsynaptic receptors has been shown to stimulate the release of oxytocin in the central nervous system where it regulates aspects of mood and behavior. Using a drug discrimination paradigm, we examined whether modulation of oxytocin receptor activity would affect conditioned behavioral responses to MDMA. Male and female Sprague Dawley rats (n=24) were trained to reliably differentiate between MDMA and a related stimulant, amphetamine (AMP), and saline using a three-lever drug discrimination paradigm. The extent to which substitution with carbetocin (an oxytocin analog) or co-administration with atosiban (an oxytocin receptor antagonist) affected drug-appropriate responding was evaluated. The tricyclic antidepressant imipramine was included as a negative control. The results supported the hypotheses that substitution with an oxytocin analog (carbetocin) would partially generalize to the MDMA training cue, whereas blocking oxytocin receptors with atosiban would result in a selective disruption of MDMA--but not AMP-appropriate responding. These findings were specific to the oxytocin receptor ligands as imipramine pre-treatment did not affect drug-appropriate responding. The results of this study implicate oxytocin receptor activation as a key MDMA-specific interoceptive cue in male and female rats and support the conclusion that this is one of the features of MDMA's subjective effects that distinguishes it from AMP.

Assessing the antidepressant-like effects of carbetocin, an oxytocin agonist, using a modification of the forced swimming test

RATIONALE

The distribution of oxytocin receptors in limbic regions, as well as evidence that exogenous oxytocin modulates affect and fear processing, suggests that this neuropeptide may have a role to play in the treatment of mood disorders.

OBJECTIVES

This study compared the effects of acute treatment with the oxytocin receptor agonist, carbetocin with the tricyclic antidepressant, imipramine, using male Sprague-Dawley rats.

METHODS

Intracerebroventricular (i.c.v.; 1, 10, 100 microg/rat), intravenous (i.v.; 2.5, 5 mg/kg), and intraperitoneal (i.p.; 2, 6.4, 20 mg/kg) carbetocin and imipramine (1.8, 5.6, 10 mg/kg, i.p.) were examined in the modified forced swim and open field tests. The mechanism of action of carbetocin was investigated by co-administering it with the oxytocin antagonist, atosiban, either centrally (5 microg/rat, i.c.v.) or systemically (1 mg/kg, i.v.).

RESULTS

Imipramine and carbetocin (all three routes of administration) both significantly reduced immobility and increased swimming and/or climbing behavior in the forced swim test. The systemic effects of carbetocin were blocked by central and systemic atosiban co-administration. Only amphetamine (2 mg/kg, i.p.), included as a false positive in order to distinguish whether antidepressant-like effects were due to psychomotor stimulation, increased locomotor activity in the open field test.

CONCLUSIONS

Carbetocin produced antidepressant-like changes in behavior via activation of oxytocin receptors in the CNS. The similarities between imipramine and carbetocin in the forced swim test suggest that drugs which target the oxytocinergic system may aid both the understanding and pharmacological treatment of depressive illness.

14beta-Arylpropiolylamino-17-cyclopropylmethyl-7,8-dihydronormorphinones and related opioids. Further examples of pseudoirreversible mu opioid receptor antagonists

14beta-4'-Chlorocinnamoylaminodihydronormorphinone (2a), and analogues, are selective pseudoirreversible antagonists of the mu opioid receptor (MOR). The preparation of analogues with ethynic bonds, replacing the ethenic bond of 2a, is described. The new ligands, in mouse antinociceptive assays, had pseudoirreversible MOR antagonist activity, which, in the case of 8b was of longer duration than that of 2a. The related codeinone (9b) had only antagonist activity in vivo, in contrast to 2a's codeinone equivalent 3a, which had potent antinociceptive activity.

Neuroendocrine and subjective responses to pharmacological challenge with citalopram: a controlled study in male and female ecstasy/MDMA users

Despite evidence that +/-3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') causes persistent alterations to the serotonergic system of animals, evidence for long-term neurological effects of ecstasy/MDMA in humans remains equivocal. The current study assessed serotonin functioning of nine male and 11 female recreational ecstasy polydrug users by measuring neuroendocrine (prolactin, cortisol) responses to pharmacological challenge with the selective serotonin reuptake inhibitor citalopram, compared with nine male and five female cannabis polydrug users and 11 male and 11 female non-drug using controls. A single-blind, randomised, placebo-controlled design was used. Subjective responses, other substance use, mood, personality traits and demographic variables were measured to control for potentially confounding variables. There were no significant differences between ecstasy polydrug users, cannabis polydrug users and non-drug using controls in neuroendocrine or subjective responses to serotonergic challenge, and there were no sex by drug group interactions. There was no relationship between extent of ecstasy use and neuroendocrine functioning, alone or in combination with potential confounding variables. Subjective responses to the pharmacological challenge (nausea, tremor, dry mouth), novelty seeking and lifetime dose of alcohol were the only variables that contributed to one or more of the neuroendocrine outcome variables. These data do not support the premise that recreational ecstasy/MDMA use results in measurable impairment of serotonergic control of endocrine activity.

14 beta-O-cinnamoylnaltrexone and related dihydrocodeinones are mu opioid receptor partial agonists with predominant antagonist activity

14-O-Cinnamoyl esters of naltrexone (6) were synthesized and evaluated in isolated tissue assays in vitro and in vivo in mouse antinociceptive assays. Their predominant opioid receptor activity was mu receptor (MOR) antagonism, but the unsubstituted cinnamoyl derivative (6a) had partial MOR agonist activity in vitro and in vivo. When compared to the equivalent 14-cinnamoylaminomorphinones (5), the cinnamoyloxy morphinones (6) as MOR antagonists had a shorter duration of action and were less effective as pseudoirreversible antagonists. The antinociceptive activity of the cinnamoyloxycodeinones (7) was not significantly greater than that of the morphinones (6), but they exhibited no evidence of any pseudoirreversible MOR antagonism. In both respects, these profiles differed from those of the equivalent 14-cinnamoylaminocodeinones (4).

Effects of modafinil on simulator driving and self-assessment of driving following sleep deprivation

OBJECTIVES

While it has been suggested that the novel wake promoting drug modafinil may have some utility with respect to drowsy driving in healthy adults, this has not been investigated until now. The present study was designed to assess the effects of modafinil on objective and self-assessed driving simulator performance during an overnight period of sleep loss.

METHODS

Sixteen healthy participants (eight males and eight females) remained awake overnight on two separate occasions during which they ingested either a single 300 mg dose of modafinil or a placebo capsule at either 0230 or 0330 h. Two hours post-treatment, participants were evaluated using measures of driving simulator performance, self-assessed driving performance and subjective alertness.

RESULTS

Modafinil treatment reduced lane deviation but had less effect on speed deviation, off-road incidents and reaction time to a concurrent task. Modafinil also improved subjective appraisals of driving performance, although its use may have resulted in overconfidence in driving ability during short trips.

CONCLUSIONS

Modafinil offers some benefits with respect to objective driving performance under conditions of sleep loss. However it may induce overconfidence, suggesting that its use as a countermeasure to drowsiness when driving requires further examination.

Corticotropin-releasing hormone in nonhuman primates

Understanding the many roles that corticotropin-releasing hormone (CRH) plays in facilitating the ordinary and extraordinary events that an individual faces during a lifetime is a complex task, and yet this knowledge is fundamental to understanding our own behaviour and physiology. During the past 25 years, the study of CRH in nonhuman primates, our closest genetic relatives, has grown rapidly. The intention of this review is to provide a broad overview of the research areas in which CRH has been investigated in monkeys and apes. The review begins with a detailed description of what we know about CRH, CRH receptors, and their distribution in the brain and periphery. The narrative then follows the life cycle, from the role of CRH in fertility, pregnancy and parturition, to the shaping of behaviour and neural processes by stressful experiences early in life. CRH is also examined in the context of its other regulatory roles, including appetitive behaviour and immune responses. Finally, the review examines the insights that nonhuman primate research offers us as to how CRH helps to shape our behaviour, whether it be our ability to socialize with our peers or to be a good parent.

Role of sex and sex steroids in mediating pituitary-adrenal responses to acute buspirone treatment in sheep

Systematic characterisation of sex differences in the serotonergic modulation of the hypothalamic-pituitary-adrenal (HPA) axis may assist with our understanding of why stress-related disorders are disproportionately represented in women. In this study, we examined the acute effects of buspirone, a serotonergic 1A receptor subtype agonist, on the endocrine endpoints of adrenocorticotrophin (ACTH) and cortisol secretion in gonadectomised male and female sheep. Each sheep was treated with an acute i.v. injection containing vehicle or buspirone (0.03, 0.1 and 0.3 mg/kg) in the presence and absence of sex steroid replacement (SSR). In males, SSR treatment consisted of testosterone (2 x 200 mg s.c. pellets) and, in females, the mid-luteal phase of the oestrus cycle was simulated by treatment with oestradiol (1 cm s.c. implant) and an intravaginal controlled internal drug release device containing 0.3 g progesterone. ACTH, cortisol, testosterone and progesterone were measured in jugular blood. Basal ACTH levels were higher in males, whereas basal cortisol levels were higher in females, regardless of sex steroid status. The magnitude of the increase in ACTH and cortisol secretion following buspirone treatment was dose-dependent. There were no differences in the ACTH responses of males and females to buspirone treatment, either in the presence or absence of sex steroid replacement. However, although the cortisol response to buspirone was greater in females, there was no discernable effect of sex steroid status in addition to this sex difference on either basal or buspirone-stimulated cortisol release. We conclude that the larger basal and buspirone-stimulated cortisol response measured in females may reflect a sex difference, either in the sensitivity of the adrenal gland to ACTH or in the catecholaminergic innervation of the adrenal gland. The lack of effect of sex and sex steroids in the ACTH secretory response to buspirone may indicate that the sex differences in serotonergic modulation of the HPA axis, as reported previously by our group, were mediated via serotonergic receptor subtypes other than the 1A receptor.

Self-administration of methohexital, midazolam and ethanol: effects on the pituitary-adrenal axis in rhesus monkeys

RATIONALE

There is disagreement in the literature with respect to how drugs of abuse affect the functioning of the hypothalamic-pituitary-adrenal (HPA) axis, and whether these changes in endocrine function may be related to the rewarding effects of these drugs.

OBJECTIVES

To determine whether reinforcing drugs with different mechanisms of action affect HPA axis function at doses at which they serve as reinforcers.

METHODS

Seven monkeys (6 male) were randomly assigned to self-administer methohexital-a barbiturate (n=4), midazolam-a benzodiazepine (n=3), or ethanol (n=5). Each monkey had a surgically implanted indwelling venous catheter, and was trained to respond on a fixed ratio of 30 lever presses to receive an injection of drug or saline. Blood samples were obtained before, during, and after the self-administration sessions for the measurement of ACTH and cortisol by radioimmunoassay.

RESULTS

Although methohexital, midazolam, and ethanol all maintained self-administration behavior across a range of doses, they differed in their effects on ACTH and cortisol. Ethanol inhibited ACTH and cortisol secretion. Methohexital and midazolam both tended to decrease ACTH and cortisol at large doses, and increase these hormones at small doses, but the HPA effects of neither drug differed significantly from when saline was available.

CONCLUSIONS

The neutral overall effect of methohexital and midazolam on HPA activity is consistent with other monkey and human studies, whereas the inhibitory effect of self-administered ethanol in the monkey contrasts with both the rat and human literature. The data in this study suggest that a change in HPA axis activity is not a requirement for drug-reinforced behavior in monkeys.

Self-administration of fentanyl, cocaine and ketamine: effects on the pituitary-adrenal axis in rhesus monkeys

RATIONALE

Drugs of abuse can affect the functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Acute administration of drugs that serve as reinforcers have been observed to stimulate the rat HPA axis, leading to the suggestion that these stimulatory effects may contribute to the development of drug-maintained behaviors.

OBJECTIVES

To determine whether reinforcing drugs that are dissimilar with respect to their mechanisms of action have similar effects on HPA axis activity at doses that are self-administered. Rhesus monkeys were randomly assigned to self-administer the mu-opioid agonist fentanyl, the psychomotor stimulant cocaine, or the NMDA antagonist ketamine.

METHODS

Each monkey was trained to press a lever in order to receive an intravenous injection of drug or saline. Blood samples were obtained before, during, and after the self-administration sessions and assayed for ACTH and cortisol by radioimmunoassay.

RESULTS

Fentanyl, cocaine, and ketamine were each self-administered across a range of doses. However, the three drugs differed in their effects on ACTH and cortisol. Cocaine stimulated ACTH and cortisol secretion, a finding that is consistent with previous rat and primate studies. Self-administration of both fentanyl and ketamine inhibited HPA axis activity. HPA inhibition by fentanyl is consistent with other monkey and human studies, and contrasts with the stimulatory effects of mu-opioids in rodents. The inhibitory effect of ketamine on ACTH and cortisol secretion contrasts with findings in the few primate studies that have evaluated NMDA antagonists. Neither fentanyl nor cocaine, at doses that maintained maximum rates of responding, produced significant changes in ACTH and cortisol levels.

CONCLUSIONS

There appears to be little commonality between different classes of abused drugs and their effects on the HPA axis, which calls into question the necessity for HPA axis stimulation in the reinforcement of drug-maintained behavior.

Antidepressants, sex steroids and pituitary-adrenal response in sheep

The importance of sex differences in major affective diseases such as depression is providing a new focus for investigating the interactions between sex, sex steroids and antidepressants. In this study, we examined the acute effects of sertraline, a selective serotonin reuptake inhibitor (SSRI) and imipramine, a tricyclic antidepressant (TCA) on the endocrine endpoints, adrenocorticotropin (ACTH) and cortisol secretion in gonadectomised male and female sheep. Each sheep was treated with an acute subcutaneous (s.c.) injection containing vehicle, sertraline (5 and 10 mg/kg), or imipramine (10 mg/kg) in the presence and absence of sex steroid replacement. In males, SSRI treatment consisted of testosterone (2 x 200 mg s.c. pellets), and in females, estradiol (1 cm s.c. implant) plus an intravaginal controlled internal drug release device containing 0.3 g progesterone. ACTH and cortisol were measured in jugular blood. Female sheep responded to sertraline treatment with dose-dependent ACTH and cortisol increases that were unchanged by sex steroid replacement. In castrated males, however, only the highest dose of sertraline increased ACTH and cortisol, and this increase was abolished in the presence of testosterone replacement. Imipramine affected neither ACTH nor cortisol secretion in either the sex or sex steroid condition. We conclude that the sex and sex steroid-related differences in the male and female responses to sertraline treatment may reflect sex and sex steroid dependent differences in serotonergic activation of the HPA axis. This highlights the potential significance of sex and circulating sex steroids in modulating neuroendocrine responses to antidepressants, and may have an impact on our understanding of the actions of these drugs in men and women.

Noncontingent and response-contingent intravenous ethanol attenuates the effect of naltrexone on hypothalamic-pituitary-adrenal activity in rhesus monkeys

BACKGROUND

The mechanism by which the opioid antagonist naltrexone suppresses overconsumption of ethanol is unclear. Oral ethanol consumption in humans increases hypothalamic-pituitary-adrenal (HPA) activity, and recent studies suggest that naltrexone may reduce ethanol consumption by modifying the HPA-stimulating effects of ethanol. The purpose of this study was to measure in rhesus monkeys the effects of ethanol and naltrexone, alone and in combination, on plasma levels of adrenocorticotropin hormone (ACTH).

METHODS

Nine adult male and female rhesus monkeys with chronic, indwelling intravenous catheters were maintained on tethers that allowed ethanol delivery and blood sampling. In one study, the monkeys received intramuscular injections of saline or 0.32 mg/kg naltrexone followed by noncontingent intravenous bolus infusions of saline or 0.3 to 1.8 g/kg ethanol. In a second study, other monkeys were given intramuscular injections of saline or 0.01 to 0.3 mg/kg naltrexone and subsequently responded on levers to receive intravenous saline or ethanol 0.03 g/kg per injection.

RESULTS

Ethanol, delivered either response contingently or noncontingently, did not produce systematic changes in ACTH plasma levels. Naltrexone alone produced increases in plasma ACTH that were attenuated by the subsequent administration of noncontingent or response-contingent ethanol. Naltrexone also produced dose-dependent reductions in intravenous ethanol self-administration. Linear regression analysis indicated that ethanol intake was negatively correlated with the plasma levels of ACTH over time.

CONCLUSIONS

The route of administration may modulate ethanol's effects on HPA activity. Ethanol may attenuate naltrexone's effect on the HPA axis by impairing HPA axis sensitivity to other stimuli. The negative correlation between ethanol intake and ACTH levels supports the notion that naltrexone's effect of increasing HPA axis activity may be related to its ability to suppress ethanol consumption.

Corticotropin-releasing hormone antagonists, astressin B and antalarmin: differing profiles of activity in rhesus monkeys

The present study compares the activity of two chemically distinct corticotropin-releasing hormone (CRH) antagonists at the level of the pituitary gland in rhesus monkeys, using exogenous CRH-stimulated increases in adrenocorticotropin (ACTH) and cortisol. Of chief interest was whether the CRH-R1-selective pyrrolopyrimidine, antalarmin, shown previously to have activity in the central nervous system (CNS), would differ in its antagonist profile from the CRH-R1- & 2-selective peptide, astressin B, which is unlikely to have access to the CNS following systemic administration. Nine rhesus monkeys (eight male), each with an indwelling venous catheter, were subjects in this study. Astressin B (0.001, 0.003, 0.03, 0.1, and 0.3 mg/kg) or antalarmin (1.0, 3.2, and 10 mg/kg) was administered as an intravenous (i.v.) pretreatment 15 min prior to administration of 1 or 10 microg/kg i.v. CRH. Antalarmin (10 mg/kg) was also administered alone on six occasions and its effects on behavior as well as on ACTH and cortisol levels were measured. Astressin B was assessed following i.v. and intracisternal (i.c.) administration. Astressin B dose-dependently abolished the CRH-stimulated ACTH and cortisol responses, with an antagonist effect lasting in excess of 24 h. Astressin B was approximately 300-times more potent when given i.c. than when it was administered via the i.v. route. By contrast, antalarmin antagonized the effects of CRH on ACTH but not cortisol at 1.0 and 3.2 mg/kg. At a larger dose, antalarmin stimulated ACTH and cortisol release and produced behavioral sedation. These latter effects diminished with repeated administration of antalarmin. The differences between astressin B and antalarmin may be due either to non-CRH receptor-mediated effects of antalarmin or to a complex interaction of antalarmin's effects at both central and peripheral CRH receptors.

Sex differences in the pituitary-adrenal response following acute antidepressant treatment in sheep

RATIONALE

Depression is more prevalent in women than in men, and therapeutic responses may also differ between the sexes. In addition, abnormal regulation of the hypothalamic-pituitary-adrenal (HPA) axis is more common in depressed women.

OBJECTIVES

To further examine these phenomena, the present study was designed to investigate whether sex differences exist in the HPA axis responses of male and female sheep following acute antidepressant administration.

METHODS

Two commonly prescribed antidepressants, imipramine (a tricyclic antidepressant, TCA; 2.0 and 5.0 mg/kg) and sertraline (a selective serotonin reuptake inhibitor, SSRI; 0.5, 2.0 and 5.0 mg/kg) were administered to gonadectomized male and female sheep via acute subcutaneous injection. Treatment order was randomized. Jugular blood was sampled for the measurement of prolactin, adrenocorticotropin (ACTH), and cortisol by radioimmunoassay.

RESULTS

Treatment with sertraline resulted in a comparable increase in prolactin secretion in male and female sheep. However, sertraline stimulated ACTH and cortisol secretion in females but not in males, a sexually dimorphic effect that was independent of circulating sex steroids. Treatment with imipramine had no effect on prolactin, ACTH or cortisol levels in male or female sheep.

CONCLUSIONS

These data suggest that the HPA axes of females are more sensitive to the stimulatory effects of serotonin following acute treatment with the SSRI, sertraline.

Antalarmin, a putative CRH-RI antagonist, has transient reinforcing effects in rhesus monkeys

RATIONALE

During the course of our investigation of antalarmin, a corticotropin-releasing hormone (CRH) antagonist, in rhesus monkeys, we noticed that large, intravenous doses of antalarmin resulted in behavioral changes that resembled intoxication.

OBJECTIVES

Antalarmin was evaluated in rhesus monkeys for its reinforcing effectiveness as well as for its effects on hypothalamic-pituitary-adrenal (HPA) axis activity.

METHODS

Twelve monkeys, each with a surgically implanted indwelling venous catheter, were trained to respond for and receive the short-acting barbiturate, methohexital. Monkeys responded on one of two schedules: a fixed ratio (FR) 10 (30 or 100), timeout (TO) 10 s schedule on which they received methohexital, antalarmin, vehicle or saline injections; or an FR30, TO 45 s during which saline, vehicle, or four different doses of methohexital or antalarmin were available. Each dose was available during a 25-min period separated by a 10-min TO. Blood samples were obtained from three monkeys before, during and after the self-administration sessions and assayed for ACTH and cortisol.

RESULTS

Antalarmin initially served as a reinforcer in 11 of 12 monkeys, although its reinforcing effects dissipated after three to four exposures under both operant schedules. Self-injection of antalarmin did not produce any change in cortisol levels, although methohexital did attenuate ACTH and cortisol release.

CONCLUSIONS

This study provides the first evidence for transient reinforcing properties of a putative centrally acting CRH-R1 selective antagonist.

Methocinnamox is a potent, long-lasting, and selective antagonist of morphine-mediated antinociception in the mouse: comparison with clocinnamox, beta-funaltrexamine, and beta-chlornaltrexamine

The irreversible mu-opioid antagonists beta-funaltrexamine (beta-FNA) and beta-chlornaltrexamine (beta-CNA) are important pharmacological tools but have a kappa-agonist activity and, in the latter case, low selectivity. This work examines whether clocinnamox (C-CAM) and the newer analog, methocinnamox (M-CAM), represent improved long-lasting antagonists for examining mu-opioid-mediated effects in vivo. beta-FNA, beta-CNA, C-CAM, and M-CAM were compared after systemic administration in mice and in vitro. beta-FNA and beta-CNA were effective agonists in the writhing assay, reversible by the kappa-antagonist norbinaltorphimine. Neither C-CAM nor M-CAM had agonist activity in vivo. M-CAM was devoid of agonist action at cloned opioid receptors. All four compounds depressed the dose-effect curve for the mu-agonist morphine in the warm-water tail-withdrawal test 1 h after administration; at 48 h, recovery was evident. In the writhing assay, the dose-effect curve for morphine was shifted in a parallel fashion in the order M-CAM >> C-CAM > beta-CNA > or = beta-FNA. In comparison with their ability to shift the dose-effect curve for bremazocine (kappa) and BW373U86 (delta), beta-CNA was the least mu-selective, followed by C-CAM < beta-FNA < M-CAM. M-CAM (1.8 mg/kg) produced a 74-fold increase in the ED(50) of morphine while showing no effect on bremazocine or BW373U86 dose-response curves. In binding assays, C-CAM and M-CAM were 8-fold selective for mu- over kappa-receptors, whereas beta-FNA and beta-CNA were mu/delta-, but not mu/kappa, selective. However, ex vivo binding assays confirmed the mu-receptor selectivity of M-CAM. M-CAM is thus a potent, long-lasting, and specific antagonist at mu-receptors in vivo that lacks confounding agonist actions.

Glucocorticoid-reinforced responding in the rhesus monkey

RATIONALE

Glucocorticoids have been reported to have rewarding effects in rats and may lead to drug-seeking behavior in humans under some circumstances.

OBJECTIVES

The present study investigated whether glucocorticoids would be self-administered intravenously by rhesus monkeys (Macaca mulatta).

METHODS

Ten monkeys, 7 male and 3 female, were maintained on a fixed ratio 10 (30 or 100), time-out 10-s schedule for 0.1 mg/kg methohexital or saline injections. Dexamethasone (0.03-0.3 mg/kg), methylprednisolone (0.1-1.0 mg/kg) and hydrocortisone (0.3-3.0 mg/kg) were periodically substituted for methohexital or saline.

RESULTS

Dexamethasone (0.3 mg/kg) was self-administered by all of the male monkeys on the first, but not on subsequent occasions. It was hypothesized that suppression of hypothalamic-pituitary-adrenal (HPA) activity by these exogenous glucocorticoids following their first presentation may have interfered with their reinforcing effects on subsequent evaluation. Subsequently, plasma adrenocorticotropin and cortisol were measured in four male monkeys to ascertain that normal basal HPA activity had resumed prior to each glucocorticoid substitution. Of the ten monkeys that were tested, only one reliably self-administered dexamethasone, methylprednisolone and hydrocortisone, and he did so regardless of whether his basal HPA activity was suppressed. This monkey differed from some of the other monkeys both behaviorally and in his response to intravenous corticotropin releasing hormone. None of the three female monkeys that were tested with selected glucocorticoid doses showed any evidence of glucocorticoid reinforcement on any occasion.

CONCLUSIONS

The results indicate that glucocorticoids were not reinforcing to the majority of monkeys in this study; nevertheless, large individual differences may exist in proclivity of monkeys to self-inject these compounds.

Cocaine-reinforced responding in rhesus monkeys: pharmacological attenuation of the hypothalamic-pituitary-adrenal axis response

Intravenously self-administered cocaine produces a dose-dependent release of adrenocorticotropic hormone (ACTH) and cortisol in male rhesus monkeys. This study investigated whether the acute disruption of cortisol and/or ACTH release had any effect on ongoing cocaine-maintained responding. Four hypothalamic-pituitary-adrenal (HPA) axis inhibitors were examined: etomidate and ketoconazole, both of which are cortisol synthesis inhibitors; astressin, a peptidic corticotropin-releasing factor (CRF) antagonist that binds CRF(1) receptors predominantly in the pituitary gland; and dexamethasone, a highly selective glucocorticoid receptor agonist whose long-lasting effects reduce or abolish the endogenous release of ACTH and cortisol. The reinforcing effects of a range of cocaine doses, with or without pretreatment with an HPA inhibitor, were evaluated using a fixed ratio 30 time-out 10-min schedule of reinforcement in six male monkeys. Blood was sampled before, during, and after self-administration sessions. Self-administration of cocaine increased plasma cortisol and ACTH. Pretreatment with etomidate and ketoconazole dose-dependently inhibited the cocaine-induced rise in cortisol and, at the highest doses, produced a compensatory increase in ACTH release. Astressin and dexamethasone attenuated or abolished cocaine-induced cortisol and ACTH release. Despite the efficacy exhibited by these pretreatments and the variety of mechanisms by which they inhibited the HPA axis, there was no evidence for any change in cocaine-reinforced behavior (response rate or infusion number), an indication that acute changes in the ACTH or cortisol response to cocaine do not play a direct role in modulating cocaine-seeking behavior under these behavioral circumstances.

Effects of response contingent and noncontingent cocaine injection on hypothalamic-pituitary-adrenal activity in rhesus monkeys

Earlier studies of cocaine's effects on the hypothalamic-pituitary-adrenal (HPA) axis used nonresponse-contingent designs in which the investigator determined dose, timing, and route of administration. It is important to evaluate whether "control" over cocaine delivery is a significant determinant of cocaine's HPA axis effect. This study measured cocaine's effects on plasma adrenocorticotropic hormone and cortisol, using nonresponse-contingent injections followed later by response-contingent cocaine delivery. In addition, the effects of cocaine history on the HPA response to a noncontingent injection of 1 mg/kg of cocaine were measured. HPA effects of corticotropin-releasing hormone (CRF) were also measured. Male and female rhesus monkeys, with surgically placed venous catheters, were tested in their home cages. Up to 13 injections of saline and cocaine (0.01-, 0.03-, 0.1-, and 0.3-mg/kg/injection) were administered at 10-min intervals (nonresponse-contingent condition) and on a fixed ratio 30, time out 10-min schedule of reinforcement. Overall, cocaine delivered response contingently produced larger, more dose-dependent HPA responses than did noncontingent delivery. The HPA response to a 1 mg/kg cocaine infusion in cocaine-naive monkeys was not predictive of the HPA effect of this dose subsequent to acquisition of cocaine self-administration. Overall, male monkeys had larger HPA responses to cocaine than did female monkeys. Finally, the HPA effects of CRF were significantly correlated with those of large cocaine doses delivered nonresponse contingently, but not with response-contingent administration.

Effects of self-administered cocaine on plasma adrenocorticotropic hormone and cortisol in male rhesus monkeys

This study was designed to examine the effects of self-administered cocaine on hypothalamic-pituitary-adrenal (HPA) axis activity in rhesus monkeys. Initially, basal release of cortisol and adrenocorticotropic hormone (ACTH) was measured in singly housed male and female monkeys (n = 9) over a 24-h period using plasma samples obtained from indwelling venous catheters. Basal cortisol and ACTH levels in both male and female rhesus monkeys demonstrated a circadian pattern of release, with peak levels for cortisol (19.60 +/- 2.16 microgram/dl) and ACTH (19.63 +/- 2.56 pg/ml) measured at 6:00 AM. The nadir for ACTH (6.27 +/- 0.62 pg/ml) occurred at 6:00 PM, preceding the cortisol nadir (5.55 +/- 1.21 microgram/dl) at 9:00 PM. The reinforcing effects of saline, 0.01, 0.03, 0.1, and 0.3 mg/kg/injection cocaine were then evaluated using a fixed-ratio 30, time-out 10-min schedule of reinforcement in seven male monkeys. Blood was sampled before, during, and after self-administration sessions. Self-administration of cocaine produced dose-dependent increases in cortisol and ACTH. One dose of cocaine (0.03 mg/kg/injection), although reliably self-administered, did not produce a significant increase in HPA axis activity. These results indicate that although cocaine dose-dependently increases HPA axis activity, the HPA effect is more likely a consequence of overall cocaine intake than it is an indicator of cocaine doses that are sufficient to maintain self-administration behavior.

3-Alkyl ethers of clocinnamox: delayed long-term mu-antagonists with variable mu efficacy

In recent years there has been considerable interest in the relationship between clocinnamox (C-CAM) and its methyl ether methoclocinnamox (MC-CAM). While C-CAM appears to be an insurmountable mu-antagonist, MC-CAM has been shown to be a potent partial agonist at mu-opioid receptors. To further investigate this relationship we prepared other ethers of C-CAM and evaluated these in opioid receptor binding assays and in vivo in mouse antinociceptive assays and in morphine-dependent monkeys. In opioid binding assays, the ethers were generally mu-selective with affinity equivalent to that of C-CAM itself. Although they displayed little or no efficacy in vitro, some of the ethers showed substantial agonist activity in the in vivo antinociceptive tests. Two of the ethers, the propargyl ether 7 and the cyclopropylmethyl ether 5, were chosen for more detailed analysis in vivo. 7 was shown to have significant mu-agonist character and was able to substitute for morphine in morphine-dependent monkeys. Interestingly, when this agonist effect abated, 7 displayed long-lasting mu-antagonism. In contrast, 5 displayed little agonist activity in vivo and was characterized as a potent, long-acting mu antagonist. Although further work is needed to determine whether metabolism is a crucial factor in determining the pharmacological profile of these ethers, it is clear that 3-O-alkylation is a useful means of varying the mu efficacy displayed by this class of acyl-substituted 14-aminomorphinones. MC-CAM itself has generated considerable interest as a potential pharmacotherapy for opiate abuse. These analogues with differing mu efficacy but retaining the long-lasting mu-antagonist effects provide further opportunities for the development of treatment drugs.

Receptor reserve and affinity of mu opioid agonists in mouse antinociception: correlation with receptor binding

In order to quantitate the extent to which opioid agonist potencies obtained in behavioral assays are determined by the apparent in vivo affinity and efficacy of the agonist, the antinociceptive effects of the mu opioid agonists morphine, fentanyl, etonitazene, and NIH 10741 were assessed before and after administration of the insurmountable mu opioid antagonist clocinnamox (CCAM) in a 55 degrees C warm-water tail withdrawal test in Swiss albino mice. Under control conditions, all four mu opioid agonists produced a full antinociceptive response with the following ED50 values (in mg/kg): morphine, 12; fentanyl, 0.47; etonitazene, 0.039; NIH 10741, 0.0051. Analysis of CCAM's effects according to Black and Leff gave the following agonist efficacy or tau values: Morphine, 4; fentanyl 15, etonitazene, 7; and NIH 10741, 59. The respective KA values were (in mg/kg): morphine, 29; fentanyl, 7.3; etonitazene, 0.22; and NIH 10741, 0.30. The major determinant of the experimentally observed ED50 values seemed to be the apparent in vivo affinity of the respective agonist and not its efficacy. KA values (expressed as mol/kg) correlated with the Ki values (in mol/l) obtained with [3H]DAMGO radioligand binding (r = 0.96 for pKA vs. pKi), although being on average 11,000-fold higher. Values for q, the available receptor fraction as determined in the behavioral experiments, correlated strongly (r = 0.96) with the q values determined by ex vivo [3H]DAMGO- and [3H]naltrexone equilibrium binding (i.e., Bmax,clocinnamox/Bmax,control), the relationship approaching unity.

Differential effects of systemically administered nor-binaltorphimine (nor-BNI) on kappa-opioid agonists in the mouse writhing assay

The opioid antagonist effects of systemically administered nor-binaltorphimine (nor-BNI) were evaluated against the kappa agonists CI-977, U69,593, U50,488, ethylketocyclazocine (EKC), Mr2034 and bremazocine, the mu agonist morphine and the alkaloid delta agonist BW-373U86 in the acetic acid-induced writhing assay in mice. All eight agonists completely and dose-dependently inhibited writhing. Antagonism of CI-977 was apparent 1 h after administration of 32 mg/kg nor-BNI, peaking after 4 h and was maintained for at least 4 weeks; no antagonist effects of nor-BNI were apparent after 8 weeks. Nor-BNI (32 mg/kg) caused little or no antagonism of morphine or BW-373U86 at 1 h and none at 24 h after nor-BNI administration. Subsequently, dose-effect curves for CI-977, U50,488, U69,593, EKC, Mr2034 and bremazocine were determined 24 h after pretreatment with 3.2, 10 and 32 mg/kg nor-BNI. Pretreatment with 3.2 mg/kg nor-BNI produced significant antagonism of all six kappa agonists, suggesting that their antinociceptive effects were mediated at least in part by nor-BNI-sensitive kappa receptors. At higher doses, nor-BNI dose-dependently shifted the agonist dose-effect curves of CI-977, U50,488, U69,593 and bremazocine, but not those of EKC and Mr2034, suggesting that the latter compounds may be producing effects via nor-BNI-insensitive receptors. Mu receptor involvement was demonstrated following a 24 h pretreatment with 32 mg/kg beta-FNA in combination with nor-BNI, which significantly increased the degree of antagonism of Mr2034 and EKC from that seen with nor-BNI alone.2+ off