The overall goal of this project is to define the factors underlying the blunted growth hormone (GH) response to pharmacological stimulation that is characteristic of children and adults with depression and to utilize this information to identify neural systems which may underlie the development of affective disorders. Blunted stimulation of the anterior pituitary hormone, GH, after a number of pharmacological stimuli, occurs in patients with depression throughout the lifespan, and the blunted GH response is one of the most consistent physiological measures documented in children and adults with depression. Children with depression tend to exhibit less exploratory behavior and more inhibited behavior in a variety of psychological tests. We are performing the current study in the monkey to determine (1) if inhibited affect and blunted GH responsiveness are linked traits, and (2) if inhibited affect and blunted GH responsiveness predispose an individual to the development of anxious and /or depressive behaviors. Therefore, this project is quantifying the behavioral characteristics of young monkeys with regard to exploratory versus inhibitory behavior, and quantifying GH responsiveness to stimulation, and then assessing the degree of correlation between these parameters. Over the past 22 years, we developed 4 behavioral testing paradigms, based directly on paradigms used in children to assess these characteristics. In 1999, we tested 110 monkeys and we found a strong correlation between blunted GH responsiveness and Alow reactivity@ in the playroom and stranger approach test s. Thus, we have evidence that at least in some individuals, these traits are linked. FUNDING NIMH MH41712 PUBLICATIONS Coleman K, Dahl RE, Ryan N, Cameron JL. Behavioral inhibition A new look at a familiar trait. Soc Neurosci Abstr 24:525, 1998 (abstract #211.1). Cameron JL, Coleman K, Bench LM, Sabatini M, Owenby T, Kupfer DJ. Differential development of anxious and depressive behaviors in rhesus monkeys dependent on the timing of maternal separation. Soc Neurosci Abstr 24:526, 1998 (abstract #211.7).
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