Janice M. Juraska - US grants

Dyslexia is a disorder in learning to read that often appears to have a congenital basis and is found more frequently in males than in females. It has been suggested that a prolonged or excessive surge of developmental testosterone may disrupt the development of the cerebral cortex and result in dyslexia. In the present proposal, this hypothesis is tested by using the rat as a model so that developmental hormone levels can be manipulated. Excess testosterone will be injected during postnatal development (days 2-8) when cortical neurons are migrating and differentiating. Three cortical areas (frontal, parietal, visual) will be sampled in weaning age males that have been injected with excess testosterone and in oil injected controls. The cortices will be examined through Nissl stains where the size of the cortical layers and soma size and density will be measured. The size of the dendritic tree as an indicator of synaptic connectivity will also be quantified in Golgi stained sections. It is hypothesized that exposure to an excess of testosterone will disrupt the organization of the cerebral cortex. This can serve as a model for what testosterone perturbations could effect in more subtle form during the development of the cortex in human dyslexics.

The purpose of this proposal is to request funds for the purchase of a Philips CM- 200 Transmission Electron Microscope to be housed in the Visualization Facility (BVF) of the Beckman Institute on the University of Illinois campus. The Principal Investigators will be using this electron microscope for a variety of studies including (i) neuroplasticity and its relationship to underlying cellular and system level processes (William Greenough), (ii) the study of monodisperse rod-coil block copolymers (Samuel Stupp), (iii) analysis of nuclear and chromosome architecture (Andrew Belmont), (iv) sex differences in the organization and behavioral function of the brain (Janice Juraska), and (v) the characterization of morphological and functional abnormalities in cerebellar neural circuitry in a genetic animal model of movement dysfunction (Louise Abbott). In addition to these core projects there are 6 other research projects from a variety of disciplines for which this instrument provides immediate or long term benefits. The purpose of obtaining a new instrument is twofold. Firstly it will provide access to an intermediate voltage instrument for biological research on the UIUC campus. The only intermediate voltage instruments in this region are exclusively devoted to material science research and biologists with projects for which higher voltages are necessary have to travel to remote sites. Secondly it will replace an existing 18 year old instrument currently located in the BVF that is suffering increasingly from age related problems. In addition to providing unique capabilities for imaging thicker specimens this microscope will have a number of other important advantages over the existing instrument. The ability to control the instrument through a computer interface and to collect micrographs using a CCD camera will greatly aid, and in certain cases be essential for several applications. Specifically, for techniques such as serial sectioning, quantitative stereology and single axis tomography which involve the collection or examination of large numbers of images, semi-automatic acquisition procedures can be devised that not only simplify the process but also ensure that the electron dose is minimized and the region of interest is maximized. Furthermore, certain applications of these 3-dimensional reconstruction techniques require literally hundreds of images per data set and these applications for practical considerations will only be feasible given the availability of direct digital data acquisition. These control and imaging capabilities will also greatly improve the routine acquisition of high quality images. Further advantages of the new microscope arise from the advances in technology over the past 20 years. These have led to simplification of alignment procedures, improvements in beam coherence, lenses and goniometer stages and the implementation of techniques for acquiring images at low doses in order to limit beam damage. The microscope will be located in the Beckman Visualization Facility which houses a number of other related instruments (including a confocal microscope, a stereology workstation and various light microscopes) as well as supporting equipment (wet lab, microtomes, darkrooms) and excellent facilities for the digital processing and analysis of images. The location of the microscope in the multi- disciplinary environment of the Beckman Institute, which also includes part of the National Center for Supercomputing Applications, provides an excellent environment to take advantage of some of the latest technology available for the on- line processing and analysis of electron micrographs. We are strongly committed to providing access to this instrument and its associated, special facilities to the campus wide user group whose research wholly or partly depends on the application of electron microscopy. There is enthusiastic commitment to this project from both the Beckman In stitute and the University as a whole. This has been demonstrated by the contribution of 50% matching funds for the project as well as the supporting infrastructure for the equipment provided by the Beckman Institute Visualization Facility.

As the proportion of post-menopausal women in the population has increased, hormone replacement has become increasingly commonplace. Recently, research has suggested that estrogens and progestins can affect higher order, cognitive behaviors when used in replacement after menopause and in their fluctuations during the menstrual cycle. Estrogens also appear to delay the onset of Alzheimer's disease, as well as modulate schizophrenic symptoms. An animal model of these effects would be useful in understanding how the ovarian steroids influence parts of the nervous system dealing with higher cognitive functions through the lifespan. The long term goal of this research is to explore the effects of ovarian steroids on cognitive behavior and concomitant neural substrates in the cycling and aging female rat. Before commencing on large and detailed studies with hormone manipulations, preliminary data are sought to select which neural area upon which to concentrate. The effects of the estropausal state of the aging rat and the phase of the cycle in young adult females on spine densities and dendritic field extent will be examined. Two cognitively relevant areas will be sampled: the hippocampus and the medial prefrontal cortex. There is preliminary data that spine densities drop precipitously with age (28-40 percent) in the medial prefrontal cortex. If this area is sensitive to ovarian hormones in aging, it would be an excellent model for age related changes in female anatomy and behavior. If it is relatively refractory to ovarian steroids, changes in the medial prefrontal cortex would be a useful model for general aging effects in both sexes.

In mammals, puberty is a time of increasing hormonal secretions as well as developing reproductive abilities. Associated changes occur in brain structures involved in these activities, and recent evidence shows that other parts of the brain involved in cognitive, non-reproductive functions also change structural features during puberty. This project uses anatomical and pharmacological approaches to examine how cellular numbers and membrane receptor molecules may change during puberty in non-reproductive areas of the brain. Ovarian hormone effects are measured in the visual cortex and in the hippocampus, which is a region known to be essential for many types of learning and memory. Potential cellular mechanisms such as programmed cell death and types of hormone receptors are studied to see how critically they depend on timing of the hormone action, compared to the traditional perinatal 'critical periods.'
Results will have substantial impact on understanding this little-studied but dynamic period related to reproductive and cognitive development, by exploring changes uniquely at the cellular level. The impact will extend beyond neuroendocrinology to the fields of biology of aging, comparative neuroanatomy, and developmental neuroscience. In addition, students will receive excellent research training in a lab that continues an excellent record of training and productivity.

[unreadable] DESCRIPTION (provided by applicant): Adolescence in humans is a period of life when alcohol use is often initiated. Unfortunately, it is also a time when some individuals develop long-lasting patterns of alcohol abuse and alcoholism. Human and animal studies have revealed that during adolescence, brain areas such as the prefrontal cortex (PFC) are undergoing significant, yet normal, changes in synaptic connectivity. These changes in synaptic organization have important implications in the adolescent and adult PFC. For example, in a recent report (Markam et al., 2007), we demonstrated region- and sex-specific decreases in the number of neurons in the medial PFC (mPFC) of adolescent compared to adult rats. It is possible that alcohol alters these normal patterns of adolescent-to adult changes in mPFC and thereby produces a particularly susceptible nervous system. Furthermore, pubertal hormones may interact with alcohol's effects in the mPFC, and this might contribute to sex differences in drinking behavior. In the research proposed here, we will use animal models to explore the effects of alcohol exposure during adolescence on the mPFC and on the operant self-administration of alcohol in adulthood. This will be accomplished by: (1) examining whether alcohol exposure during adolescence alters decreases in neuron number in the rat mPFC and if gonadal hormones contribute to alcohol's effects; and (2) investigate whether alcohol exposure during adolescence alters alcohol drinking behavior in adulthood and if there is an influence of sex and hormonal status. Rats will be divided into eight different groups (n = 10/group) based on sex (male or female), hormone status (intact or pre-pubertal gonadectomy), and adolescent exposure to alcohol (saline or 3.0 g/kg ethanol). As adults (PND 90), rats will be either euthanized for brain removal and subsequent stereological analysis of the number of neurons in the mPFC (Aim 1) or they will begin training for operant self-administration of alcohol (Aim 2). Ultimately, the information learned in these studies will help us understand if alcohol-induced brain changes are a contributing factor to the high rates of alcoholism in individuals who begin drinking at an early age. [unreadable] [unreadable] [unreadable]

Common chemicals in the environment have the potential to disrupt the role of gonadal hormones during human development. Examples include the widely used chemicals bisphenol A, which is estrogenic, and the phthalates, which are anti-androgenic. Both chemicals are the focus of this formative center proposal. Besides the potential consequences for reproductive functions, cognitive neural functions, which are also influenced by gonadal hormones, may be altered by these endocrine disruptors. The present pilot project is preliminary and within its limited scope and budget, will initially model the effects of only bisphenol A in hooded rats, an animal model where sex differences in the cerebral cortex have been documented and are known to be influenced by hormonal milieu during both the perinatal and peripubertal period. The effects of bisphenol A on neuron number, a very basic building block of function, will be explored in two cortical areas of rats, the visual cortex and the medial prefrontal cortex (PL and IL) where sex differences have been found . Separate groups of animals will be exposed to 0, 4, 40 or 400 mug/kg/day perinatally or peripubertally. When the rats reach adulthood, the number of neurons in each cortical area will be quantified with stereological methods. In addition to their established sex differences in neuron number, these cortical regions play a role in behaviors analogous to those that will be assessed in human infants and adolescents in Projects 1 and 2. The behavioral consequences of cortical alterations will also be investigated in a visual spatial task, the radial arm maze, which consistently shows sex differences in several laboratories. As adults, all rats will be tested on a 17-arm radial maze with both baited and unbaited arms so that both reference and working memory can be tested. Within animal comparisons between behavioral performance and neuron number will be made.

Endocrine disruptors are chemicals that can interfere with hormonal functions and many are found in widely used consumer products. Hormones play a critical role in the formation ofthe nervous system, which makes it vulnerable to these common chemicals. Two ofthe major examples of endocrine disruptors, the phthalates and bisphenol A (BPA), are known to disrupt both the gonadal steroids and thyroid function. Both chemicals are the focus of this proposal using a rodent model. Increases in body weight are found with exposures to the phthalates and BPA, and this weight gain is exacerbated by high fat diets. High fat diets alone interfere with cognition in both rodents and human children. BPA and the phthalates, as well as high fat diets, all increase oxidative stress and inflammation, and these environmental factors can have epigenetic effects. We hypothesize that the combination of the exposure to endocrine disruptors and a high fat diet during development will be especially pernicious for cognitive behavior and the neural regions of the brain that are important for this behavior, such as the cerebral cortex. The experimental design entails exposure to either a phthalate mixture or BPA with or without a concurrent high fat diet. Two different times during development are targeted in the two Aims. Aim 1 examines the long-term effects after exposure during pre- and post-natal development when the nervous system is rapidly changing. Aim 2 examines exposure during adolescence, a time when the final growth and pruning ofthe nervous system occurs, especially in the prefrontal area of the cerebral cortex. The end point for both of these aims will be the number of neurons, the number and types of glia including microglia (which increase with inflammation) and dopaminergic innervation through immunolabeling of tyrosine hydroxylase in the medial prefrontal cortex. Tests of cognition will include object recognition and intra- and extra-dimensional shifts. There will be accompanying measurements of body weight and fat composition and indices of oxidative stress, inflammation and epigenetic changes in these markers.