Grant Number: 5P50MH045156-170014
Project Title: DYSFUNCTION OF DLPFC PYRAMIDAL NEURONS IN SCHIZOPHRENIA
PI Information: DAVID A. LEWIS, lewisda@upmc.edu

Abstract:
The central hypothesis of our Center focuses on critical disturbances in the regulation of cognition and behavior in schizophrenia that reflect functional abnormalities in the intrinsic circuitry of the dorsolateral prefrontal cortex (DLPFC) and in its interconnections with other brain regions. These functional disturbances are hypothesized to arise during posnatal development as a consequence of alterations in the molecular signals and structural elements that determine synaptic efficacy in the affected neural circuits. These alterations include somatodendritic morphological abnormalities, such as smaller somal volumes, decreased dendritic arbor size and complexity, and reduced dendritic spine density, of pyramidal neurons, the principal excitatory projection neurons of the neocortex. Furthermore, these somatodendritic abnormalities in schizophrenia may be specific to, or at least present to a greater degree in, a subset of pyramidal neurons. Because a neuron' s dendritic arbor is a maj or determinant of its functional circuit properties, pyramidal neuron somatodendritic abnormalities, in concert with related synaptic disturbances, may be central to DLPFC-mediated cognitive dysfunction in schizophrenia. Consequently, knowledge of the specific subsets of pyramidal neurons that are affected in schizophrenia is essential for determining both the potential causes of these abnormalities and their contributions to disturbed DLPFC information processing. Thus, using an integration of experiments in postmortem human brain specimens and in nonhuman primates, the studies proposed in this project are designed to determine 1) the laminar location(s) of the DLPFC pyramidal neurons that exhibit somatodendritic abnormalities in schizophrenia; 2) the molecular phenotypes of pyramidal neurons that furnish different types of extrinsic projections in monkey DLPFC; 3) the somatodendritic integrity of molecularly-identified subpopulations of DLPFC pyramidal neurons in schizophrenia; and 4) the molecular mechanisms that may contribute to developmental somatodendritic changes in monkey DLFPC pyramidal neurons. These investigations have a number of conceptual and technical links with other Center projects and depend upon support provided by all of the proposed cores.

Thesaurus Terms:
cognition, neurophysiology, prefrontal lobe /cortex, pyramidal cell, schizophrenia
antipsychotic agent, axon, biological signal transduction, dendrite, electrophysiology, haloperidol, major depression, messenger RNA, morphology, neural plasticity, neurogenesis, neurogenetics, phenotype, psychopathology, serotonin inhibitor
Macaca, behavioral /social science research tag, fluorescent dye /probe, human tissue, postmortem

Institution: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
350 THACKERAY HALL
PITTSBURGH, PA 15260
Fiscal Year: 2006
Department:
Project Start:
Project End:
ICD: NATIONAL INSTITUTE OF MENTAL HEALTH
IRG: ZMH1

The Journal of Neuroscience, March 21, 2007, 27(12):3295-3304

Amygdala Gene Expression Correlates of Social Behavior in Monkeys Experiencing Maternal Separation

Michael J. Sabatini,^1,3 Philip Ebert,^7,8 David A. Lewis,^1,2 Pat Levitt,^1,7,8 Judy L. Cameron,^1,4,5 and Károly Mirnics^1,6,8

Departments of ¹Psychiatry, ²Neuroscience, and ³Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, ⁴Departments of Physiology and Pharmacology and Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239-3098, ⁵Oregon National Primate Research Center, Beaverton, Oregon 97006-3448, and Departments of ⁶Psychiatry and ⁷Pharmacology and ⁸Vanderbilt Kennedy Center for Human Development, Vanderbilt University, Nashville, Tennessee 37203

Maternal separation paradigm
A total of 12 female rhesus monkeys born in the breeding colony at the University of Pittsburgh Primate Research Laboratory were used for these studies. At birth, each monkey was arbitrarily selected to enter the "1 week separated," "1 month separated," or "control" experimental groups (n = 4 per group). All monkeys in this study spent the first week of life in a single cage with their mother. During this initial period, monkeys were housed in cages in temperature-controlled (24 ± 2°C) communal rooms with artificial lighting from 7:00 A.M. to 7:00 P.M., Purina Monkey Chow was provided once daily (number 5045; Ralston Purina, St. Louis, MO), and water was available ad libitum. After the first week of life, the animals were handled differently depending on experimental group assignment. At 1 week of age, monkeys designated as 1 week separated were removed from their mothers and placed in a single cage immediately adjacent to a group-rearing pen that they would ultimately join. After a 5–7 d period of learning to bottle feed (ad libitum Similac with Iron baby formula; Abbott Laboratories, Columbus OH), these monkeys were introduced into the group-rearing environment. One week separated monkeys spent weeks 3–12 in the group-rearing environment. Conversely, at 1 week of age, monkeys designated as 1 month separated were introduced into a group-rearing pen with their mothers. One month separated monkeys spent weeks 2–4 in the group-rearing environment with their mothers. At 4 weeks of age, 1 month separated monkeys' mothers were removed from the group-rearing environment, and the infants were placed in the single cage positioned identically as described for the 1 week separated group. After a 5–7 d period of learning to bottle-feed, these monkeys were reintroduced into the group-rearing environment. One month separated infants again spent weeks 6–12 in the group-rearing environment. Monkeys from both separation groups were provided a soft-cotton stuffed toy when they were in the single cage learning to bottle feed. This toy could be held to provide contact comfort. Control monkeys were introduced into the group-rearing pen at 1 week of age with their mother, and they remained there with their mother for the study's entirety, weeks 2–12. The group-rearing pen consisted of 4–5 monkeys of varying ages, with no monkey more dominant than the adult female mother (when present). An adolescent female was always present in the social rearing groups because they have been shown to be particularly attentive to infants. The group-rearing pen, measuring 14 x 11 x 12 feet, was cement block construction with a several inch bed of wood shavings on the floor, four perches at various heights, and a chain-link penfront. A "nursery chamber", measuring 2 x 2 x 3 feet, was placed in each pen and accessible only to infants. Infants had access to bottles of standard human artificial formula that were replaced three times each day. Other monkeys were fed one meal per day between 9:00 and 10:00 A.M. of Purina high-protein monkey chow supplemented several times a week with fresh fruit and seeds strewn in the bedding to encourage foraging. Water was available ad libitum. Artificial lighting in the hallways was on from 7:00 A.M. to 7:00 P.M. each day, and sky lights above each pen admitted natural light. Temperature was maintained at 24 ± 2°C. The infant monkeys were weighed weekly, and all animals, regardless of maternal separation status, reported a comparable weight gain over time (supplemental material 1, available at www.jneurosci.org ).

Behavioral assays
Behavioral assessments were initially made at the time of separation and again during the third month of life and will be described briefly below.
Acute separation behaviors. At the time of maternal separation, each monkey (four 1 week separated and four 1 month separated) was videotaped in the single nursery cage setting for 10 min per focal session. This occurred two to four times per day for the first 3 d after maternal separation, and every other day thereafter, until the infant was transferred to the group-rearing pen. All behaviors displayed by the focal monkeys in the acute separation cage (Table 1)
Table 1. Acute separation behaviors