Christopher N. Honda - US grants

This proposal is concerned with the conversion of "non-lemniscal" afferent input into thalamocortical relay cell output in the ventrobasal (VB) nuclei of the cat thalamus. Such mechanisms may form a fundamental basis for the sensory discriminative aspects of pain, and as such, become important in future studies concerning pain relief in both te normal and pathologic states. The specific aims are: (1) determine the morphological characteristics of the terminal arborizations of individual spinothalamic (STT) and cervicothalamic (CTT) tract axons in VB, (2) determine the relationships of STT and CTT axon terminals to thalamcortical relay and intrinsic neurons in VB, (3) examine the morophological characteristics and exact synaptic patterns of individual, functionally identified and intra-axonally labeled STT and CTT terminal arbors in VB, (4) correlate differences in the synaptic patterns of non-lemnisal and lemniscal afferents with differences in their functional properties. Three primary sets of experiments are to be conducted at both light and electron microscopic levels: (a) a morphological analysis of the branching and termination patterns of anterogradely labeled STT and CTT axons in VB, (b) a study combining the morphological analysis of anterogradely labeled STT and CTT axon terminations with the characterization of their postsynaptic targets in VB, and (c) a physiological study of individually identified STT and CTT fibers utilizing intraxonal labeling techniques to establish structure/function relationships of non- lemniscal afferent fibers in VB.

Endogenous opioids modulate neurotransmission through a number of different sensory and motor systems. The present proposal is concerned in general with the modulation of sensory transmission and in particular with opioid modulation of nociceptive sensory systems at the spinal level. The intent of this proposal is to utilize recently developed antibodies to examine in detail the localization of opioid receptors in relation to different functional classes of primary afferent neurons in rats and monkeys. In addition, experiments will determine the spatial relationships between opioid receptors, opioids, and functionally and anatomically identified spinal neurons. In making this proposal, the following specific aims will be addressed: 1. To determine in rats and monkeys what functional classes of primary afferent neurons express opioid receptors. 2. To determine in rats the anatomical and spatial relationships between opioid receptor-containing neuronal elements and retrogradely labeled spinothalamic tract neurons. 3. To determine in monkeys the anatomical and spatial relationships between opioid receptors and functional or morphological subclasses of spinothalamic tract neurons. The presently proposed experiments will determine the anatomical distribution of opioid receptors at a resolution not possible before. Knowledge obtained from these experiments will aid in our understanding of basic opioid mechanisms, and as such will further our understanding of mechanisms related to the modulation of nociceptive and painful information in both the normal and pathologic states.

teacher; science education; health science research; secondary schools; training level; education evaluation /planning;

The proposed project will provide research experience for 12 disadvantaged high school students and five K-12 inservice and preservice science teachers, and will serve to foster an interest in higher education in general and in health science careers in particular. The Program consists of a summer component and an academic year component. The summer component will provide research experience for high school students and K-12 inservice teachers in laboratories of Health Science faculty. In addition, a number of shared enrichment activities outside of the laboratory will be implemented. The academic year component will provide research and laboratory experience for pre-service K-12 teachers designed to complement their classroom science training. In addition, the summer component will provide continued interactions between summer student and teacher participants in the form of classroom visits, long term mentoring, and field trips to the University.

[unreadable] DESCRIPTION (provided by applicant): [unreadable] [unreadable] This Stage 1 Cebra application seeks to test the feasibility of simultaneous functional down-regulation of two ATP gated ion channels present in the subset of nociceptive sensory neurons. The P2X2 and P2X3 purinergic receptors arechosen for investigation because recent studies suggest that many sensory neurons behave as if they express these two receptors in a heteromultimeric configuration (P2X2/3), and because antisense oligonucleotide knockdown of P2X3 alone results in modest attenuation of some nociceptive behaviors. The underlying hypotheses of this proposal is that simultaneous knockdown of P2X2 and P2X3 purinergic receptors is an effective approach to interfere with nociceptive processing, and that it is a more efficient way to target heteromeric receptor configurations than approaches targeting either P2X2 or P2X3 receptors alone. An antisense oligonucleotide approach combined with immunohistochemical, behavioral, and electrophysiological measures will be used to determine whether simultaneous delivery of antisense oligonucleotides for P2X2 and P2X3 will decrease the expression of P2X2 and P2X3 in sensory neurons and reduce nociceptive behaviors. In addition, these studies will determine for the first time whether antisense treatment will alter the response properties of functionally identified sensory neurons with intact receptive fields. In making this proposal, existing methodologies will be integrated and applied as a new paradigm. Findings from these experiments could contribute to the development of viable therapeutic alternatives to the use of analgesic agents such as opiate compounds that have high potential for tolerance and dependence. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Opiate compounds are potent and effective centrally acting analgesic agents, but systemic administration is usually accompanied by undesirable effects such as sedation, gastrointestinal disturbance, and respiratory depression. In addition, tolerance, withdrawal, and addiction inevitably result from prolonged use. This proposal concerns the function of opioid receptors in the periphery, and how their activation contributes to an endogenous opioid analgesia system operating outside the central nervous system. We have shown in normal cornea and skin that direct peripheral application of morphine is not effective in altering acute nociceptive responses. However, in inflamed tissue, peripheral morphine reverses behavioral hyperalgesia in cornea and reduces excitability of identified cutaneous nociceptors in a concentration-dependent and naloxone reversible fashion. We now seek to determine under what conditions this endogenous opioid system is effective, and what mechanisms contribute to enhanced availability of peripheral opioid receptors after injury or inflammation. Electrophysiological techniques will be used to determine (1) which opioid receptor types mediate the inhibitory effects of morphine on identified afferent neurons innervating inflamed somatic tissue, and (2) if sensory neurons develop a sensitivity to morphine in an experimental model of neuropathic pain. Quantitative immunohistochemistry will determine (3) the time course of changes in expression of opioid receptors in the somata and peripheral processes of sensory neurons under inflammatory and neuropathic conditions, and (4) if increased numbers of opioid receptors are detectable on the membranes of peripheral processes of sensory neurons following inflammation. Better understanding of how endogenous opioid systems are regulated would provide valuable insights into potential development of therapeutic alternatives to traditional systemic delivery of opiates for the relief of pain.