Sergio D. Iniguez, Ph.D. - US grants

DESCRIPTION (provided by applicant): Childhood depression was almost unthinkable until several years ago. Now we not only know that major depressive disorder (MDD) exists in children and adolescents, but that it is also a common condition. Early-life MDD has been correlated with antisocial personality, bipolar disorder, and suicide. It is estimated that youngsters who suffer from depression often develop conduct and anxiety disorders, and that 20-25% develop substance abuse disorder. Consequently, this has resulted in a disproportionate increase in the prevalence of, antidepressants prescribed to youths below 20 years of age. Despite the heightened rates in antidepressant use, little is known about the long-term behavioral and neural adaptations resulting from antidepressant treatment during periods before adulthood. To address this need in our basic knowledge, the experiments described in this proposal will examine the behavioral responses to antidepressant treatment in "adolescent" rats (postnatal day [PD] 35), and will further assess the long-term behavioral consequences of adolescent antidepressant treatment in adulthood (PD90+). This will be accomplished within the framework of the following specific aims: [1] determine the efficacy of antidepressant treatment in juvenile rats, [2] assess long-term consequences of chronic adolescent antidepressant treatment on the sensitivity to reward- (natural, drug) and mood-related (anxiety, stress) behaviors in adulthood, and [3] evaluate the integrity of reward-related biological markers [extracellular signal regulated protein kinase (ERK)], within the mesolimbic system, following chronic adolescent antidepressant exposure. We expect that antidepressant exposure during adolescence will induce long-lived alterations associated with responses to stress, anxiety, natural- and drug-rewarded behaviors. Furthermore, we expect site-specific neurochemical alterations (ERK fluctuations within the ventral tegmental area) to be a factor mediating these mood- and reward-related alterations as a function of early-life antidepressant exposure.

? DESCRIPTION (provided by applicant): Pediatric depression was almost unthinkable until several years ago. Now we not only know that major depressive disorder (MDD) exists in children and adolescents, but that it is a common condition. It is estimated that children and adolescents who suffer from MDD often develop conduct and anxiety disorders, and that up to 25% develop substance abuse disorder. Consequently, this has resulted in a disproportionate increase in the prevalence of antidepressants prescribed to populations below 20 years of age. Despite the heightened rates in antidepressant use, little is known about the potential long-term behavioral and neural adaptations resulting from antidepressant treatment during early development. To address this problem, the experiments described in this proposal will examine the long-term behavioral consequences of early life (postnatal day [PD] 35-49) exposure to fluoxetine, a selective serotonin reuptake inhibitor, using C57BL/6 male and female mice. This will be accomplished within the framework of the following specific aims: [1] assess long-term consequences of chronic adolescent antidepressant treatment on the sensitivity to reward (drug), mood related behaviors (stress), and memory in adulthood (PD80+), and [2] evaluate the integrity of mood-related biological markers [extracellular signal regulated protein kinase-1/2 (ERK)], within the hippocampal formation, following chronic adolescent antidepressant exposure. It is expected that antidepressant exposure during adolescence will induce long-lived alterations associated with responses to stress, drug-rewarded behaviors, and memory. Furthermore, it is expected that site-specific neurochemical adaptations (ERK fluctuations within the hippocampus) to be a factor mediating these behavioral alterations as a function of juvenile antidepressant exposure. Collectively, the results of this preclinical work will provide first-line evidence on the potential risks of antidepressant exposure during adolescence.

? DESCRIPTION (provided by applicant): Pediatric depression was almost unthinkable until several years ago. Now we not only know that major depressive disorder (MDD) exists in children and adolescents, but that it is a common condition. It is estimated that children and adolescents who suffer from MDD often develop conduct and anxiety disorders, and that up to 25% develop substance abuse disorder. Consequently, this has resulted in a disproportionate increase in the prevalence of antidepressants prescribed to populations below 20 years of age. Despite the heightened rates in antidepressant use, little is known about the potential long-term behavioral and neural adaptations resulting from antidepressant treatment during early development. To address this problem, the experiments described in this proposal will examine the long-term behavioral consequences of early life (postnatal day [PD] 35-49) exposure to fluoxetine, a selective serotonin reuptake inhibitor, using C57BL/6 male and female mice. This will be accomplished within the framework of the following specific aims: [1] assess long-term consequences of chronic adolescent antidepressant treatment on the sensitivity to reward (drug), mood related behaviors (stress), and memory in adulthood (PD80+), and [2] evaluate the integrity of mood-related biological markers [extracellular signal regulated protein kinase-1/2 (ERK)], within the hippocampal formation, following chronic adolescent antidepressant exposure. It is expected that antidepressant exposure during adolescence will induce long-lived alterations associated with responses to stress, drug-rewarded behaviors, and memory. Furthermore, it is expected that site-specific neurochemical adaptations (ERK fluctuations within the hippocampus) to be a factor mediating these behavioral alterations as a function of juvenile antidepressant exposure. Collectively, the results of this preclinical work will provide first-line evidence on the potential risks of antidepressant exposure during adolescence.

Principal Investigator Iñiguez, Sergio Diaz ABSTRACT Pediatric major depressive disorder (MDD) is a common condition. Children and adolescents who suffer from MDD often develop conduct and anxiety disorders, and up to 25% develop substance abuse disorder. Consequently, this has resulted in a disproportionate increase in the prevalence of antidepressant medications prescribed to populations below 20 years of age. Despite the heightened rates in antidepressant prescriptions, juveniles are less likely to respond to traditional treatments (i.e., selective serotonin reuptake inhibitors) for the management of MDD. Recently, ketamine (KET), an anesthetic, has shown promise as a treatment for MDD. While exciting for the field of psychiatry ? that a novel pharmaceutical can be used to alleviate MDD symptoms ? the efficacy/safety of KET exposure during development has not been thoroughly examined. This is surprising, given that KET is known to have drug-abuse potential. Thus, to address this problem, the experiments described in this proposal will examine the enduring neurobehavioral consequences of early life (postnatal-day [PD] 35-44) exposure to KET, using C57BL/6 mice. This will be accomplished within the framework of the following specific aims: [1] assess the long-term consequences of chronic adolescent KET (with/without social stress exposure) on sensitivity to reward (drug), mood, and memory-performance in adulthood (PD80+), and [2] to evaluate the integrity of mood-related biological markers [mammalian target of rapamycin (mTOR)-related signaling], within the hippocampal formation. It is expected that juvenile KET exposure will mediate long-lived behavioral alterations associated with enhanced drug abuse potential (i.e., cocaine), altered responses to stress, and memory-related impairment(s). Furthermore, it is expected that site- specific neurochemical adaptations (mTOR fluctuations within the hippocampus) will be a factor mediating the drug-abuse and memory-associated behavioral adaptations as a function of adolescent KET exposure. Collectively, the results of this preclinical work will provide first-line evidence on the potential enduring risks of juvenile KET exposure. PHS 398/2590 (Rev. 06/09) Page Continuation Format Page