James I. Koenig - US grants

The secretion of adrenocorticotropin (ACTH) from the anterior pituitary gland in response to stress is under the stimulatory drive of several hypothalamic peptides, e.g., corticotropin-releasing factor (CRF) and arginine vasopressin (AVP). Other factors such as vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI) and serotonin (5-HT) also are thought to stimulate the secretion of ACTH. In contrast, the adrenal glucocorticoids exert a powerful negative feedback influence on ACTH secretion. The goal of these studies is to determine the physiological and pharmacological effects of VIP, PHI and 5-HT in controlling the secretion of ACTH in vivo. It is proposed to study the effect of exogenous VIP or PHI administration on the secretion of ACTH, CRF and AVP in vivo. Furthermore, utilizing passive immunization techniques, the role of endogenous VIP and/or PHI in stimulating ACTH secretion following adrenalectony or stress will be studied. Inasmuch as VIP and PHI appear to be hypothalamic hormones which are secreted into the hypophysial portal circulation, it is proposed to study the factors which regulate the secretion of these peptides into the portal blood and origin of these peptides in portal blood by collecting hypophysial portal blood from the anesthetized rat. Anatomical studies have demonstrated that VIP and 5-HT are present in overlapping loci in the suprachiasmatic and paraventricular nuclei and in the hippocampus. It is proposed to study the functional interrelationships between 5-HT and VIP in regulating ACTH secretion which involves these anatomical loci. Finally, it has been suggested that the hippocampus may mediate some of the negative feedback effects of the glucocorticoids. The importance of hippocampal VIP and 5-HT will be studied in mediating glucocorticoid negative feedback effects on ACTH secretion. These studies taken together will enhance our knowledge of the neurochemical interactions involved in the regulation of ACTH secretion. In man, hypercortisolemia is prevalent in patients suffering from depressive disorders and in the elderly. The etiology of the hypercortisolemia during depressive illnesses may involve changes in the metabolism of 5-HT or in the negative feedback signal produced by the glucocorticoids. The elderly may suffer hippocampal neuron loss which results in inappropriate feedback signals being relayed to the hypothalamic centers regulating ACTH secretion. Without more complete knowledge of the mechanisms governing ACTH secretion, there will be little hope of unraveling the mysteries of these idiopathic hypercortisolemic states.

adrenocorticotropic hormone; neuropeptides; gene expression; peptide chemical synthesis; hormone regulation /control mechanism; hormone biosynthesis; psychobiology; vasopressins; messenger RNA; neurotoxins; neurons; hormone metabolism; glucocorticoids; Cushing's syndrome; paraventricular nucleus; tyrosine; arginine; molecular pathology; psychoneuroimmunology; neurochemistry; neural transmission; norepinephrine; corticotropin releasing factor; in situ hybridization; antibody neutralization test; laboratory rat;

DESCRIPTION (Applicant's Abstract): Stress, either of physical or psychological origin, has been implicated as a trigger for a number of devastating autoimmune and neuropsychiatric disorders, such as lupus erythematosus, depression, and schizophrenia. While we have a firm understanding of the physiology of the final common effectors involved in the stress response, i.e., corticotropin-releasing hormone and vasopressin, our knowledge of brain mechanisms activating the hypothalamic-pituitary-adrenal axis is more limited. Clearly, the glucocorticoids have powerful consequences associated with their hypersecretion during and after stress. However, the underlying neural mechanisms providing input to the neurons of the paraventricular nucleus are the substrates of neuropsychiatric illness. A more detailed understanding of the molecular and cellular relationships between neurotransmitters and neuromodulators in the regulation of hypothalamic-pituitary-adrenal axis secretions may provide keys to unlocking disorders, such as depression or schizophrenia or discoveries that may lead to new therapeutics for these disorders. Glutamate is the most abundant excitatory neurotransmitter in the neuroendocrine axis, and has been implicated in the etiology of schizophrenia, yet the physiological role of this excitatory amino acid transmitter is poorly understood in the regulation of the hypothalamic-pituitary-adrenal axis. One of the aims of the proposed studies is to characterize the molecular and cellular events elicited by excitatory amino acid receptor activation in the control of the secretions of the hypothalamic-pituitary-adrenal axis. Hypoglycemia, a well-characterized and readily controllable "metabolic stress," precipitates excitatory amino acid release in the brain. Consequently, another aim of these investigations is to employ molecular and neuroendocrinological techniques to explore the participation of excitatory amino acid receptor activation in the hypothalamic-pituitary-adrenal axis during hypoglycemia. These studies aim to reveal important new information about the regulation of stress hormone secretion by glutamate and may be significant in better understanding brain mechanisms in neuropsychiatric and other stress-related disorders.

DESCRIPTION (provided by applicant): Oxytocin (OT) and vasopressin production are concentrated in the hypothalamic paraventricular and supraoptic nuclei. Fibers emanating from these cells innervate limbic brain areas that are involved in the control of social behavior. Several human diseases, like schizophrenia and autism, have prominent social manifestations that adversely affect the individuals suffering from these diseases. Approximately one-third of schizophrenic patients are afflicted with the negative symptoms of schizophrenia (e.g. asociality, anhedonia, avolition of speech), which are not treated by the currently available antipsychotic medications. The biological basis of these symptoms is unknown. My laboratory has developed a novel animal model that exhibits many aspects of the schizophrenia phenotype including compromised social drive and function. In this application, we propose to use this animal preparation to investigate the etiopathophysiology of the social incompetence exhibited by these animals and its relationship to schizophrenia. Our preliminary data point to an alteration in the brain OT system as the precipitating factor for the social dysfunction of prenatally stressed male rats. Therefore, our overarching hypothesis is that prenatal stress exposure compromises the development of the brain OT neurons and the dysfunction of the oxytocinergic neurons generate the social dysfunction present in the prenatally stressed rats, and potentially in schizophrenic patients with negative symptoms. To test this hypothesis the following specific aims are proposed. Specific Aim 1. Examine the role of maternal factors, like maternal behavior and glucocorticoids, in the prenatal stress-induced changes in adult male rat social behavior, paraventricular nucleus OT expression and OT receptor binding in amygdala, lateral septum and bed nucleus of the stria terminalis. Specific Aim 2. Examine the developmental timing of prenatal stress-induced changes in the brain OT system and social behavior. Specific Aim 3. Examine whether prenatal stress alters the expression of genes that regulate OT components in the developing and adult rat brain. Specific Aim 4. OT reverses the social deficit in prenatally stressed rats when injected into the amygdala. Examine the role of OT receptors in other brain regions to normalize prenatal stress-induced alterations in social behavior. Specific Aim 5. Examine the state of the oxytocinergic system in human schizophrenic hypothalamic and amygdalar tissues. Together these studies will provide new information about a potential etiological agent for schizophrenia; a mechanism by which a schizophrenia-related behavioral abnormality arises and a putative treatment to restore normal social function to affected animals, and potentially human schizophrenics, also.

Drug discovery for schizophrenia has been oriented towards psychosis, but primary negative symptoms and the cognitive impairments are robustly associated with poor functional outcomes. This CIDAR application embraces the notion that novel preclinical and clinical approaches are necessary for the development of new therapies for the negative symptom and cognitive impairment domains of schizophrenia. We have generated a novel pre-clinical animal preparation based on developmental and epidemiological data showing that mid-gestational stress exposure increases the risk for developing schizophrenia. This preclinical model is ideally suited to launch a translational investigation of novel drugs for use in treating schizophrenia. Exciting pre-clinical findings from the use of this model form the basis for studying oxytocin's effects in clinical and pre-clinical models of the negative symptoms of schizophrenia, as proposed in this CIDAR application and in Projects #1, 2 and 3. Additionally, this precliinical model will be used to evaluate whether significant cliniclal findings regarding the alpha? nicotinic receptor and cognition can be extended to the pre-clinical situation. The overall hypothetical framework for this CIDAR application is based on the following propositions: 1) that negative symptoms and cognitive impairments may be separate clinical targets for drug development, and a drug with efficacy for one domain may not have an effect on the other;2) that a drug effect on a domain in a clinical trial will be associated with a similar effect in a pre-clinical rat model and a non-clinical human model and 3) that oxytocin receptor stimulation and alpha-7 nicotinic receptor stimulation will benefit behaviors relating to the negative symptoms and cognitive impairments of schizophrenia, respectively. We will examine the following hypotheses in the pre-clinical rat model: Hypothesis 1 A: oxytocin will improve behaviors related to the negative symptoms of schizophrenia but not the cognitive impairments in the pre-clinical rat model of schizophrenia. Hypothesis 1B: improvement of social function in the pre-clinical rat model will be accompanied by normalization of oxytocin mRNA production and receptor function. Hypothesis 2A: alpha-7 nicotinic receptor stimulation with DMXB-A, an alpha-7 nicotinic receptor partial agonist, will improve cognition in the pre-clinical rat model but not behavioral assays related to the negative symptoms of the disease. Hypothesis 2B: improvements in cognition will be accompanied by increased expression of alpha-7 nicotinic receptors in the hippocampus of the rat pre-clinical model. Data from this Project will also be used to address the overall CIDAR hypotheses.

and the cognitive impairments are robustly associated with poor functional outcomes. This CIDAR application embraces the notion that novel preclinical and clinical approaches are necessary for the development of new therapies for the negative symptom and cognitive impairment domains of schizophrenia. We have generated a novel pre-clinical animal preparation based on developmental and epidemiological data showing that mid-gestational stress exposure increases the risk for developing schizophrenia and is termed the unpredictable prenatal stress model of schizophrenia (PSup). The PSup model is ideally suited to launch a translational investigation of novel drugs for use in treating schizophrenia because the behavioral phenotype of the rats displays similarity to the behavioral symptoms of schizophrenic patients and thte enduring nature of the behavioral changes. Using the PSup animal preparation, we have generated exciting pre-clinical findings showing beneficial effects of oxytocin on social withdrawal behavior exhibited by the PSup rats. These data support the hypothesis that oxytocin may produce beneficial effects in clinical and pre-clinical models of the negative symptoms of schizophrenia, as proposed in this CIDAR application and in Projects #1, 2 and 3. Additionally, PSup rats will be used to evaluate whether significant cliniclal findings regarding the alpha? nicotinic receptor and cognition can be extended to the pre-clinical situation. The overall hypothetical framework for this CIDAR application is based on the following propositions: 1) that negative symptoms and cognitive impairments may be separate clinical targets for drug development, and a drug with efficacy for one domain may not have an effect on the other;2) that a drug effect on a domain in a clinical trial will be associated with a similar effect in a pre-clinical rat model and a non-clinical human model and 3) that oxytocin receptor stimulation and alpha-7 nicotinic receptor stimulation will benefit behaviors relating to the negative symptoms and cognitive impairments of schizophrenia, respectively. The purpose of the Pre-clinical Studies Core is to generate the PSup rats needed to pursue the studies proposed in Project #1 of this CIDAR application and to establish the platform of behavioral outcome measures needed to evaluate the predictive validity of testing the selected compounds in the PSup animal preparation.

DESCRIPTION (provided by applicant): Stress is a leading presenting, precipitating and exacerbating factor for a wide array of biomedical pathological conditions, with an especially strong etiological link with mental disorders. Researchers have made significant recent advances in understanding the neurobiology of stress. Determining the molecular, cellular and neurosystems mechanisms through which stress alters brain function is essential to understanding the mechanistic relationship between stress and mental disorders. A Neurobiology of Stress Workshop is being organized to be held June 15-18, 2010 at Boulder Colorado. This rigorous scientific meeting will bring together preclinical and clinical researchers who study stress-brain interactions and their impact on mental and physical health. This Workshop addresses an important need to strengthen the community of stress researchers in a manner that will maximize the productivity and clinical benefit of future stress research. Thus, the Workshop will provide a unique opportunity for researchers to participate in face-to-face examination of recent research advances, to share perspectives, identify relevant issues, debate controversies and exchange diverse expertise. Five sessions are planned in which invited speakers will present new research work, novel ideas, and examination of clinically relevant issues. Session themes are organized around specific stress-related factors and their impact on mental health and disease. Specifically, these stress-related factors of focus are 1) energy metabolism, 2) lifespan epochs, 3) risk factors, 4) resistance/resilience factors, and 5) cognitive and emotional factors. One of the five sessions is a targeted multidisciplinary cross-fertilization session featuring metabolism/energy balance and its relationship with stress neurobiology. In addition to the discussion time within each session, the Workshop features extensive time for interaction among all attendees at the opening data blitz reception, shared daily lunch period, Poster Session, and a social hour that will feature an informal discussion of the future of stress research. A priority of the Workshop is to foster the professional development of new investigators and women by including them at all levels of meeting organization and Program participation. Further the Workshop will nurture career development of graduate students and postdoctoral researchers by giving them ample opportunity to participate in the Workshop via the data blitz session, Poster Session, discussion sessions, "Meet the Speaker" luncheon roundtables, and an on-line Meeting Issues Blog. Travel Grants will be made available to select trainees through a merit based application process, with a detailed plan in place to recruit applications from interested minority candidates. Funds are requested in this application to support Trainee Travel Grants, Poster Session costs, and meeting related costs for new investigators, women and minorities that are participating in the Scientific Program. This Workshop will address critical needs in the stress research community that are ongoing, and consequently we envision this meeting as serving as a model for a recurring series of Stress Workshops. PUBLIC HEALTH RELEVANCE: The adverse effects of stress on mental and physical health has come to the fore as one of the most pressing biomedical problems in our society. The proposed Neurobiology of Stress Workshop to be held June 15-18, 2010 in Boulder Colorado will bring together basic, preclinical and clinical researchers and affiliated trainees in order to significantly enhance the productivity and clinical benefit of future stress research.