PTSD in women is associated with a block in conversion of progesterone to the GABAergic neurosteroids allopregnanolone and pregnanolone measured in plasma.

There is a need to identify new and more effective treatments for posttraumatic stress disorder (PTSD). Allopregnanolone and its stereoisomer pregnanolone (together termed ALLO) are metabolites of progesterone that positively and allosterically modulate GABA effects at GABAA receptors, thereby reducing anxiety and depression. Previous research revealed that women with PTSD had low cerebrospinal fluid (CSF) ALLO levels and a low ratio of ALLO to the allopregnanolone precursor 5α-DHP, consistent with deficient activity of the ALLO synthetic enzyme 3α-hydroxysteroid dehydrogenase (3α-HSD). The current study examined ALLO and the ratio of ALLO to 5α-DHP in plasma at rest and in response to psychophysiological stressors in trauma-exposed, medication-free women with and without PTSD. Participants were examined twice in random order during the early follicular phase (eFP) and mid-luteal phase (mLP) of the menstrual cycle. Plasma neurosteroids were measured using gas chromatography-mass spectrometry. Results indicate that the ALLO to 5α-DHP ratio in plasma increases between the eFP and mLP. In addition, women with PTSD have a lower ratio of ALLO to 5α-DHP than trauma-exposed healthy women, as well as blunted increases in this ratio in response to a moderately stressful laboratory procedure, i.e., differential fear conditioning, across the menstrual cycle. Clinically feasible testing for 3α-HSD dysfunction is critical to translating this line of research into clinical care. Measurement of this ratio in plasma could facilitate patient stratification in clinical treatment trials, as well as precision medicine targeting of treatments that address ALLO synthesis deficits in women with PTSD.

The socially-isolated mouse: a model to study the putative role of allopregnanolone and 5alpha-dihydroprogesterone in psychiatric disorders.

Allopregnanolone (3alpha,5alpha-TH PROG) and 5alpha-dihydroprogesterone (5alpha-DH PROG), the two most important neuroactive steroids synthesized in the brain, potently modulate neuronal activity by allosterically regulating GABA action at GABA(A) receptors or by changing specific GABA(A) receptor subunit gene expression, respectively. We recently reported [Proc. Natl. Acad. Sci. USA 95 (1998) 3239] that in patients with severe depression there is a decrease in the CSF levels of 3alpha,5alpha-TH PROG, which is normalized by treatment with drugs (i.e. fluoxetine) that improve psychopathology. The mechanism by which fluoxetine and other selective serotonin reuptake inhibitors normalize 3alpha,5alpha-TH PROG CSF levels appears to involve a direct stimulation of 3alpha-hydroxysteroidoxidoreductase (3alpha-HSD), an enzyme that catalyses the reduction of 5alpha-DH PROG into 3alpha,5alpha-TH PROG. Here, we propose the use of socially-isolated mice that have a downregulation of 3alpha,5alpha-TH PROG and of 5alpha-DH PROG expression to establish a model to study the behavioral consequences of this deficiency. After 4-6 weeks of isolation, these mice exhibit increased anxiety and aggressive behavior and also a decreased response to the administration of GABA-mimetic drugs. In these mice, the decrease in 3alpha,5alpha-TH PROG is selectively normalized by the use of fluoxetine in doses that reduce behavioral abnormalities. In addition, the expression of 5alpha-reductase Type I mRNA and protein was lower in socially-isolated mice than that in group-housed mice whereas 3alpha-HSD mRNA expression remained unchanged. The results of these studies may enable us to design drugs that specifically affect neurosteroidogenic enzymatic activities and may provide an efficacious treatment for the psychopathologies associated with psychiatric disorders.

Increased pituitary and adrenal reactivity in premenopausal women with posttraumatic stress disorder.

BACKGROUND: Limited studies of hypothalamic-pituitary-adrenal axis regulation in posttraumatic stress disorder have been performed in premenopausal women. We therefore undertook a study of hypothalamic-pituitary-adrenal axis regulation in this population. METHODS: Outpatient posttraumatic stress disorder subjects were compared with healthy, age- and weight-matched nontraumatized subjects. Subjects were free from psychotropic medications, alcohol and other illicit substances for at least 4 weeks before study. Menstrual cycle phase was determined by monitoring the LH surge and plasma progesterone levels. Corticotropin releasing factor and adrenocorticotropin stimulation tests, as well as 24-hour urinary-free cortisol measurements were performed. RESULTS: Corticotropin releasing factor test: Baseline adrenocorticotropic hormone and cortisol levels did not differ between the 12 PTSD and 11 comparison subjects, but the posttraumatic stress disorder group had greater adrenocorticotropic hormone and cortisol responses to corticotropin releasing factor, as well as a later cortisol peak. Adrenocorticotropic hormone test: Baseline cortisol levels did not differ between the 10 posttraumatic stress disorder subjects and seven controls, but the posttraumatic stress disorder group showed greater cortisol responses to adrenocorticotropic hormone. Peak cortisol responses to corticotropin releasing factor and adrenocorticotropic hormone were correlated with each other and with 24-hour urinary-free cortisol excretion. CONCLUSIONS: Pituitary and adrenal hyperreactivity to exogenous corticotropin releasing factor and adrenocorticotropic hormone is demonstrated in premenopausal women with chronic posttraumatic stress disorder. Cortisol hyperreactivity thus may play a role in the pathophysiology of posttraumatic stress disorder in women.

Clinical and functional correlates of posttraumatic stress disorder in urban adolescent girls at a primary care clinic.

OBJECTIVE: To identify clinical and functional correlates of posttraumatic stress disorder (PTSD) in trauma-exposed urban adolescent girls. METHOD: Ninety female adolescents aged 12 to 21 years (mean 17.3 years) who presented for routine medical care at an adolescent primary care clinic were assessed with self-report questionnaires and interviews for trauma exposure, posttraumatic stress symptoms, other psychopathology, and psychosocial, family, and school function. RESULTS: Ninety-two percent (n = 83) endorsed at least one trauma. Witnessing community violence (85.6%) and hearing about a homicide (67.8%) were the most common traumatic events endorsed. Twelve (14.4%) and 10 (11.6%) traumatized girls met DSM-IV symptom criteria for full and partial PTSD, respectively. Compared with traumatized girls without PTSD, girls with PTSD were significantly more depressed, used more cigarettes and marijuana, and were more likely to have failed a school grade, been suspended from school, or been arrested. CONCLUSIONS: Urban adolescent girls are exposed to multiple types of trauma. Whereas most develop at least one posttraumatic stress symptom, girls who meet full symptom criteria for PTSD show evidence of other psychopathology, increased cigarette and marijuana use, and poorer school performance. Further research is needed to identify and treat inner-city girls with PTSD.

Low baseline and yohimbine-stimulated plasma neuropeptide Y (NPY) levels in combat-related PTSD.

BACKGROUND: Consistent with many studies demonstrating enhanced reactivity of the sympathetic nervous system in posttraumatic stress disorder (PTSD), the administration of yohimbine, a noradrenergic alpha(2)-antagonist, has been shown to increase core symptoms of PTSD and to induce greater increases in plasma 3-methyl-4-hydroxy-phenyl-glycol (MHPG) in subjects with PTSD compared with healthy control subjects. In turn, neuropeptide Y (NPY) has been shown to inhibit the release of norepinephrine from sympathetic noradrenergic neurons. METHODS: In the following study, plasma NPY responses to yohimbine and placebo were measured in a subgroup of 18 subjects with PTSD and 8 healthy control subjects who participated in the previous study of the effect of yohimbine on plasma MHPG. RESULTS: The PTSD subjects had lower baseline plasma NPY and blunted yohimbine-stimulated increases in plasma NPY compared with the healthy control subjects. Within the PTSD group, baseline plasma NPY levels correlated negatively with combat exposure scale scores, baseline PTSD and panic symptoms, and yohimbine-stimulated increases in MHPG and systolic blood pressure. CONCLUSIONS: This study suggests that combat stress-induced decreases in plasma NPY may mediate, in part, the noradrenergic system hyperreactivity observed in combat-related PTSD. The persistence of this decrease in plasma NPY may contribute to symptoms of hyperarousal and the expression of exaggerated alarm reactions, anxiety reactions, or both in combat veterans with PTSD long after war.

The role of mesoprefrontal dopamine neurons in the acquisition and expression of conditioned fear in the rat.

The mesoprefrontal dopamine neurons are sensitive to physical, pharmacological and psychological stressors. In this report, the role of these neurons in the response to classical fear conditioning was investigated. 6-Hydroxydopamine lesions to the medial prefrontal cortex reduced dopamine levels to about 13% of controls but did not alter behavior during the acquisition of fear conditioning. As expected, conditioned fear increased dopamine metabolism (3,4-dihydroxyphenylacetic acid/dopamine ratio) in the nucleus accumbens in sham-lesion rats. The medial prefrontal 6-hydroxydopamine lesions did not alter this effect. During the expression, however, lesioned rats demonstrated a delayed extinction of the conditioned response without an overall increase in the initial conditioned response. This effect was consistent in rats receiving 6-hydroxydopamine lesions before or after the acquisition period. The calculated rates of extinction showed that the 6-hydroxydopamine lesioned rats had a reduced rate of extinction, but not acquisition, of fear conditioning. The results presented in this manuscript indicate that the mesoprefrontal dopamine neurons are involved in co-ordinating the normal extinction of a fear response but do not alter the acquisition of fearful behaviors. These data are consistent with the conclusion that the mesoprefrontal dopamine neurons are involved in maintaining the animal's response adaptability with regards to stress-related changes in the external environment.

Plasma neuropeptide Y (NPY) increases in humans in response to the alpha 2 antagonist yohimbine.

Previous studies have shown that the intravenous administration of yohimbine, an alpha 2 antagonist, increases norepinephrine turnover and has related anxiogenic effects in humans. We herein report that yohimbine also increases plasma neuropeptide Y (NPY) in healthy human subjects. This finding is consistent with previous reports in animals, but contrasts with a previously reported study in humans. NPY is a 36 amino acid peptide neurotransmitter located in sympathetic and nonsympathetic nerve fibers, as well as in brain structures such as the locus coeruleus, where it is colocalized with norepinephrine. NPY has been shown to inhibit locus coeruleus neuronal firing, decrease norepinephrine release, and increase postsynaptic noradrenergic signal transduction. When administered centrally, NPY also has anxiolytic properties. This study therefore suggests that yohimbine challenge may be useful in assessing NPY and noradrenergic system interactions in neuropsychiatric disorders such as panic disorder or post traumatic stress disorder in which noradrenergic system dysfunction has been observed.

Role of the amygdala in the coordination of behavioral, neuroendocrine, and prefrontal cortical monoamine responses to psychological stress in the rat.

Exposure to mild stress is known to activate dopamine (DA), serotonin (5-HT), and norepinephrine (NE) metabolism in the anteromedial prefrontal cortex (m-PFC). Neuroanatomical site(s) providing afferent control of the stress activation of the m-PFC monoaminergic systems is at present unknown. The present study used a conditioned stress model in which rats were trained to fear a substartle-threshold tone paired previously with footshock and assessed for behavioral, neuroendocrine, and neurochemical stress responses. Bilateral NMDA-induced excitotoxic lesioning of the basolateral and central nuclei of the amygdala was performed before or after training. Pretraining amygdala lesions blocked stress-induced freezing behavior, ultrasonic vocalizations, adrenocortical activation, and dopaminergic metabolic activation in the m-PFC. Post-training amygdala lesions blocked stress-induced m-PFC DA, 5-HT, and NE metabolic activation. Post-training amygdala lesions also blocked stress-induced freezing and defecation, and greatly attenuated adrenocortical activation. These data provide evidence of amygdalar control of stress-induced metabolic activation of the monoaminergic systems in the m-PFC, as well as amygdalar integration of behavioral and neuroendocrine components of the rat stress response. These results are discussed in terms of possible relevance to stress-induced exacerbation of schizophrenic symptoms and the pathophysiology of posttraumatic stress disorder.

5-HT1a agonist +/-8-OH-DPAT modulates basal and stress-induced changes in medial prefrontal cortical dopamine.

Serotonergic 5-HT1a agonists have recently been suggested to be effective in the treatment of human anxiety disorders. The neural mechanisms responsible for their clinical efficacy are unknown. In this study, we investigated the effects of +/-8-hydroxy-2(di-n-propylamino)tetralin [+/-8-OH-DPAT], a serotonergic 5-HT1a agonist, on basal and stress-induced changes in dopamine utilization and release in selected forebrain dopamine terminal fields in the rat. Dopamine utilization and release were respectively assessed by neurochemical analysis of ex vivo brain tissue and by microdialysis in the freely moving animal. Systemic +/-8-OH-DPAT at doses below 225 micrograms/kg had not effect in any region except to slightly decrease dopamine utilization in the nucleus accumbens. However, at a dose of 225 micrograms/kg, +/-8-OH-DPAT significantly increased basal dopamine utilization and release in the medial prefrontal cortex, while simultaneously decreasing serotonin release in this area. By contrast, the same dose of +/-8-OH-DPAT decreased extracellular dopamine in the striatum. The effect of +/-8-OH-DPAT on the response of the dopamine system to mild footshock stress was also assessed. This 5-HT1a agonist diminished the magnitude of footshock-induced increases in prefrontal cortical dopamine utilization. These data suggest that 5-HT1a agonists may dose-dependently modulate both basal and stress-induced changes in dopamine utilization in the medial prefrontal cortex. The possible relevance of these findings to the observed clinical efficacy of 5-HT1a agonists in anxiety disorders is discussed.

The NMDA glycine site antagonist (+)-HA-966 selectively regulates conditioned stress-induced metabolic activation of the mesoprefrontal cortical dopamine but not serotonin systems: a behavioral, neuroendocrine, and neurochemical study in the rat.

Animals confronting threatening stimuli respond with a coordinated set of autonomic, neuroendocrine, neurochemical, and behavioral responses that constitute the stress response. The role of the NMDA receptor and its glycine modulatory site was investigated in a rat conditioned stress model. Behavioral, neuroendocrine, and neurochemical analyses were conducted. Regional dopamine (DA) and serotonin (5-HT) utilization was assessed by postmortem tissue measurements of metabolite-to-parent neurotransmitter ratios. Rats were conditioned to fear a tone previously paired with footshock. The following day, rats were systemically administered saline or the NMDA glycine site antagonist (+)-HA-966 before exposure to thirty minutes of conditioned stress. Conditioned stress resulted in a selective increase in medial prefrontal cortical DA and 5-HT utilization, elevation in serum corticosterone, and freezing behavior in control animals. The conditioned stress-induced increase in DA utilization in control animals was also detected in the lateral prefrontal cortex and nucleus accumbens, whereas DA utilization was not affected in the perirhinal or cingulate cortices, lateral-basolateral amygdaloid complex, anterior ventromedial caudatoputamen, or posterior dorsolateral caudatoputamen. Pretreatment with (+)-HA-966 at 15 mg/kg completely abolished the conditioned stress-induced increase in DA utilization in the medial and lateral prefrontal cortices. This effect was regionally specific since (+)-HA-966 pretreatment did not block increased DA utilization in the nucleus accumbens. This effect was also neurochemically specific since the stress-induced increase in 5-HT utilization in the medial prefrontal cortex was not affected by (+)-HA-966 pretreatment. Pretreatment with (+)-HA-966 did not affect stress-induced serum corticosterone elevation but did attenuate the freezing response. Control experiments demonstrated that (+)-HA-966 pretreatment did not (1) induce sedation, (2) interfere with habituation to a novel environment, (3) alter basal DA, 5-HT, or serum corticosterone levels, or (4) block acquisition of aversive memories. These data suggest that the NMDA receptor complex and associated glycine modulatory site may play an important role in the afferent control of the mesoprefrontal cortical DA system during conditioned stress. The relevance of these findings to schizophrenia and human anxiety disorders such as post-traumatic stress disorder are discussed.