Pentagastrin-induced sleep panic attacks: panic in the absence of elevated baseline arousal

Rabeprazole and Psychiatric Symptoms

Objective:

To report the case of a patient who developed marked anxiety associated with episodes of panic attacks after starting rabeprazole therapy.

Case Summary:

An otherwise healthy 55-year-old woman was prescribed rabeprazole 20 mg/day administered in the morning tor persistent symptoms of dyspepsia. Ten days later, she presented with a 7 day history of marked anxiety associated with panic attacks, night terror (pavor nocturnus), episodic mental confusion, and attention deficit. Within 2 days of discontinuing rabeprazole, the patient recovered completely from the neuropsychiatric manifestations. Subsequent esomeprazole therapy did not cause psychiatric symptoms.

Discussion:

Rabeprazole-induced hypergastrinemia may have played a role in this neuropsychiatric adverse reaction. Several lines of evidence have indicated that gastrin-releasing peptide, whose release is mediated by proton pump inhibitor (PPI)–induced secretion of gastrin, is involved in regulating aspects of behavior that might be altered in disorders such as anxiety, depression, and dementia. The fact that rabeprazole has the highest capacity of inducing gastrin increase compared with other PPIs might explain why our patient's panic symptoms disappeared after switching to esomeprazole. Based on the Naranjo probability scale, rabeprazole was the probable cause of the adverse reaction.

Conclusions:

Specific studies are needed to investigate the potential role of PPI-induced hypergastrinemia in neuropsychiatrie adverse reactions.

The role of the lateral amygdala in the retrieval and maintenance of fear-memories formed by repeated probabilistic reinforcement

The lateral nucleus of the amygdala (LA) is a key element in the neural circuit subserving Pavlovian fear-conditioning, an animal model of fear and anxiety. Most studies have focused on the role of the LA in fear acquisition and extinction, i.e., how neural plasticity results from changing contingencies between a neutral conditioned stimulus (CS) (e.g., a tone) and an aversive unconditioned stimulus (US) (e.g., a shock). However, outside of the lab, fear-memories are often the result of repeated and unpredictable experiences. Examples include domestic violence, child abuse or combat. To better understand the role of the LA in the expression of fear resulting from repeated and uncertain reinforcement, rats experienced a 30% partial reinforcement (PR) fear-conditioning schedule four days a week for four weeks. Rats reached asymptotic levels of conditioned-fear expression after the first week. We then manipulated LA activity with drug (or vehicle) (VEH) infusions once a week, for the next three weeks, before the training session. LA infusions of muscimol (MUSC), a GABA-A agonist that inhibits neural activity, reduced CS evoked fear-behavior to pre-conditioning levels. LA infusions of pentagastrin (PENT), a cholecystokinin-2 (CCK) agonist that increases neural excitability, resulted in CS-evoked fear-behavior that continued past the offset of the CS. This suggests that neural activity in the LA is required for the retrieval of fear memories that stem from repeated and uncertain reinforcement, and that CCK signaling in the LA plays a role in the recovery from fear after the removal of the fear-evoking stimulus.

Sleep and anxiety disorders

Sleep disturbances commonly are associated with anxiety disorders, in particular generalized anxiety disorder, panic disorder, and posttraumatic stress disorder. Sleep loss may exacerbate and contribute to relapse of these conditions. Core features of panic disorder and posttraumatic stress disorder occur in relation to sleep (sleep panic attacks or re-experiencing nightmares). Investigation of sleep in anxiety disorders provides clues to mechanisms of arousal regulation relevant to insomnia and pathologic anxiety. Established treatments for anxiety disorders and insomnia have many overlapping components; however, optimal sequencing and integration of the approaches remain under-investigated.

Assessment and treatment of nocturnal panic attacks

Nocturnal panic (NP), waking from sleep in a state of panic, is a common occurrence among patients with panic disorder, with 44-71% reporting at least one such attack. NP is a non-REM event that is distinct from sleep terrors, sleep apnea, nightmares or dream-induced arousals. This review outlines recent advances in the characterization of NP, as well as current approaches to the assessment and treatment of NP. In contrast to earlier work, more recent studies suggest that patients with NP do not differ from patients without NP on sleep architecture, sleep physiology, self-reported sleep quality and severity of panic disorder. However, more precise measurement of physiological precipitants and features is warranted. Assessment of NP focuses on ruling out other explanations for NP, with differential diagnosis based on interviews, sleep polysomnography and ambulatory recording of sleep. Psychological treatment (cognitive-behavioral therapy) targets misappraisals of anxiety sensations, hyperventilatory response, and conditioned reactions to internal, physical cues. Recent evidence supports the efficacy of this approach, however, controlled studies on pharmacological agents in the treatment of NP are lacking. Research is needed to examine the effects of combined cognitive-behavioral therapy and medications, compared to medication alone in the treatment of NP.

Nocturnal panic: biology, psychopathology, and its contribution to the expression of panic disorder

The latest studies on psychopathology and biology of nocturnal (or sleep) panic attacks and other findings related to sleep in panic disorder are reviewed. While some of the newer articles doubt that nocturnal panics present a more severe variation of panic disorder, older studies and some newer articles support this notion. Some studies suggest that nocturnal panic maybe also be associated with other, more severe pathology. This interesting syndrome, or variant of disorder, may have its own etiology, psychopathology, and underlying biology.

Effect of repeat exposure on neuroendocrine and symptom responses to pentagastrin

The cholecystokinin (CCK-B) agonist pentagastrin stimulates dose-dependent release of adrenocorticotropin (ACTH) and cortisol in humans, likely via direct pharmacological action at pituitary CCK-B receptors. Pentagastrin also produces side effects, however, which may be experienced as novel or anxiety arousing and could contribute to ACTH release. Available data suggest that pentagastrin's activation of the hypothalamic-pituitary-adrenal (HPA) axis is unrelated to anxiety symptoms themselves, but novelty effects have not been examined in this model and do strongly activate this system in animals. To further explore the impact of novelty and anxiety symptoms on HPA responses, pentagastrin was administered twice to 12 subjects (six male, six female) under single-blind conditions. Repeat pentagastrin injection was associated with a slight habituation in the magnitude of symptom and HPA axis responses, but robust HPA and symptom responses were seen following both injections. No relationships were found between anxiety symptoms and HPA activity and the modest symptomatic and neuroendocrine habituation appeared to occur independently. Pentagastrin may release ACTH and cortisol through direct pharmacological action, perhaps enhanced on first exposure by psychologically mediated novelty effects. Novelty, per se, is not likely the primary mediator of the HPA response. This model may be useful for further study of cognitive-emotional modulators of HPA axis activity.

The neurobiology and control of anxious states

Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.

Neurosteroid secretion in panic disorder

Evidence that neurosteroids have anxiolytic effects in animal models of anxiety has suggested that alterations of neurosteroid secretion might be implicated in the pathogenetic mechanisms of anxiety disorders in humans. In 25 female patients with panic disorder (PD) and 11 healthy female controls, we measured plasma concentrations of progesterone (PROG), pregnenolone (PREG), allopregnanolone (3alpha,5alpha-tetrahydroprogesterone=3alpha,5alpha-THPROG), dehydroepiandrosterone (DHEA) and tetrahydrodeoxycorticosterone (3alpha,5alpha-THDOC) during a drug-free month and during the following month of paroxetine therapy. The neurosteroids were measured during the early follicular phase, the mid-luteal phase and the premenstrual phase of both months (days 7, 22 and 27 from the beginning of the cycle). Significantly higher levels in patients than controls were found in PROG during the mid-luteal phase of both months, PREG in the premenstrual phase in the drug-free month, 3alpha,5alpha-THPROG during the follicular phase of the drug-free month and during the premenstrual phase of the therapy month, and 3alpha,5alpha-THDOC during the premenstrual phases of both months. DHEA levels did not differ in patients and controls. These results suggest that neurosteroids in PD are hypersecreted, possibly as an attempt to counteract the anxiogenic underlying hyperactivity of the hypothalamo-pituitary-adrenal axis and to improve a reduced GABA(A) receptor sensitivity.