Karen J. Berkley - US grants

The long-range goal of the studies funded by this grant is to provide functionally-relevant, anatomical descriptions of the patterns of divergence and convergence of the central nervous system pathways involved in somatic sensation. Because of the complexity of the interrelationships between the elements in these pathways, these descriptions are necessary before an understanding of the neural mechanisms underlying various aspects of somatic sensation, such as touch, pain and kinesthesia can be achieved. The work proposed for the next grant period is focused upon two regions---the odrsal column nuclei (DCN) and the zona incerta (ZI). The results obtained so far on DCN tentatively indicate that the DCN are involved in at least two independent systems. One is the previously well-known dorsal column-DCN-ventrobasal complex (VB)-somatic sensory cortex relay pathway with its associated "lemniscal" characteristics. The other, previously unrecognized system consists of a separate set of DCN neurons (of unknown characteristics) and the interconnections of these neurons with other targets besides VB. Studies in the next grant period will continue ongong experiments in which multiple labeling strategies are being used to obtain as complete a description as possible of the spatial, morphological and collateralization characteristics of DCN's multiple efferent systems. If time permits, additional electrophysiological studies will be initiated to investigate the somatic response properties of some of the differentially-projecting neurons in DCN. One of DCN's major diencephalic targets besides VB is the zona incerta. The ZI in addition receives dense input from the reticular formation and cerebellum. Although these and other results indicate that ZI is a diencephalic region that, like VB and the intralaminar complex, has some function in somatic sensation, ZI has been relatively ignored in this regard. Accordingly, other studies proposed for the next grant period will use multiple labeling strategies and electrophysiological techniques to examine the connective anatomy of ZI together with the somatic response properties of its neurons. The aim of the studies is to provide anatomical and physiological data that will increase our understanding not only of DCN's and ZI's specific somatic sensory functions, but also how their functions relate to those of other parts of the somatic pathways.

Tritiated proline when injected into the nervous system of cats, is incorporated preferentially into glial cells. The unusual incorporation pattern suggested the existence of a previously unrecognized glial-neuronal communication system. This system involves the translocation of molecules from glial cells into neuronal soma followed by axonal transport and partial redistribution to adjacent glial processes. The long-term goals of the research are to characterize the molecules involved in the translocation sequence and to understand the operations and functions of the system. These studies will utilize anatomical and biochemical methods to characterize the preferential incorporation of proline into feline glia and to determine the translocation process to neurons. Other studies will document the suitability of the rat and determine the use of optimal neuronal pathways. Future studies will address questions regarding possible functions of the glial-neuronal communication system during neuronal activity and maturation. Although neuroscientists agree that brain function is carried out by combined actions of neurons and glia, the actual mechanisms of communication and cooperation are poorly understood. These studies are designed to improve this understanding.

DESCRIPTION (adapted from applicants abstract): The long-range goal of the proposed research is to improve understanding of the neural mechanisms of gynecological pain. The studies use behavioral and electrophysiological methods to characterize escape behaviors and CNS activity elicited by pelvic organ stimulation in female rats under various normal and pathological conditions. Specific aims for the next 5 years focus on mechanisms of vaginal hyperalgesia (VAGH) and will test three hypotheses. (1) Reproductive senescence and VAGH: Vaginal sensitivity in women increases after menopause to produce VAGH. This VAGH is thought to be due to the effects of estrogen loss on vaginal tissue. The hypothesis that senescence-VAGH is associated with hypoestrogenic-conditions and changes in physical properties of the vagina will be tested in rats by using behavioral methods in awake rats to study how escape responses to vaginal distension and how vaginal tone both changes as the rats age through senescence and following hormonal manipulations. (2) Endometriosis and VAGH: Viable endometrial tissue outside the uterus in women is associated with infertility and pelvic pain, including VAGH. Because estrogen is necessary for ectopic endometrial viability, behavioral methods and hormonal manipulations will be used on a rat model of endometriosis to test the hypothesis that endometriosis-VAGH, in contrast to senescence-VAGH, depends upon estrogen and is independent of vaginal tone. (3) CNS mechanisms: Despite the fact that sensory afferents of the rat female reproductive tract convey highly specific and topographically-organized information to the CNS, many neurons in the spinal cord and thalamus respond convergently to stimulation of pelvic organs and skin, and the responses can change depending on changing CNS control factors. Even more surprisingly, this situation appears also to apply to neurons in the two other ports-of-entry for pelvic information to the CNS, the gracile and solitary nuclei, suggesting that these two portal nuclei warrant inclusion, along with the spinal cord, in studies of CNS pain mechanisms. Accordingly, electrophysiological studies will compare how responses to stimulation of pelvic organs and skin by neurons in the gracile and solitary nuclei, as well as in the spinal cord, change as a consequence of estrous state, senescence-VAGH, and endometrious-VAGH.

DESCRIPTION (provided by applicant): In healthy individuals, activities of the lower urinary, gastrointestinal, and reproductive tracts are coordinated with each other to avoid conflict. Although the mechanisms of this multisystem coordination are not well understood, there are many locations within the central and peripheral nervous systems where the coordination might be organized. The existence of such viscero-visceral interactions in health raises questions about how they might influence signs and symptoms of pathophysiology. For example, how does uterine or colon pathology affect functions of the healthy or diseased bladder? Although research on this issue has been scant, recent studies suggest that multisystem interactions can indeed exert profound influences on signs and symptoms of urological and other pelvic organ pathophysiology, a situation that has considerable significance for diagnosis and treatment. These recent studies have also shown that another profound influence on such signs and symptoms is reproductive status (e.g., ovarian cyclicity). Accordingly, the eventual long-term goal of this new research program using female rats will be to improve our understanding of these influences and their mechanisms in a manner that has potential for translating to the clinic. The aim of this two-year R21 application is to explore protocols to initiate this program. Two sets of studies on urethane-anesthetized female rats are proposed. The first set will test two hypotheses: (i) that pathophysiology in the uterus or colon influences motility of the healthy bladder, and (ii) that the influences vary with estrous stage. For these studies, transurethral cystometry will be used to measure micturition thresholds before and after inflammation (or sham inflammation) of the uterus or colon in rats in different estrous stages. The second set will test the hypothesis that the interactions between the inflamed uterus (or colon) and healthy bladder require input into thoracolumbar spinal segments. In these studies, the influence of uterine (or colon) inflammation on micturition thresholds will be compared in groups of rats with previously-transected or sham-transected thoracolumbar (T13-L2) dorsal roots. Results from these exploratory studies will be then be used to develop a longer program of research.