(taken from the application): Fibromyalgia syndrome (FMS) is characterized by pain throughout the body (multifocal) with specific areas that are particularly sensitive to pressure. Primary afferent C-fibers are believed to be important in pain transmission. Some C-fibers contain substance P (SP) and are regulated by nerve growth factor (NGF), while others are characterized by the enzyme thiamine monophosphatase (TMPase) and are supported by glial derived neurotrophic factor (GDNF). Consistent with the hypothesis that C-fibers are involved in FMS, the concentrations of SP and NGF in the CSF of these patients are elevated. What initiates this is not known. C-fibers are depolarized by kainic acid, an excitatory amino acid analog. A single i.p. injection of kainic acid increases TMPase stain in the dorsal spinal cord, suggesting sprouting, and produces a persistent (> 12 weeks) decrease in the intensity of mechanical stimulation required to evoke withdrawal responses in rats similar to the lowered threshold of pressure required to produce pain in patients with FMS. Whether kainic acid produces these effects by increasing GDNF or NGF activity along nociceptive pathways is not known. We will test the hypotheses that the mechanical hyperalgesia produced by kainic acid is caused by enhancement of neurotrophic activity that supports C-fibers (NGF and GDNF) which, in turn, enhances proteins associated with these nociceptive pathways. To accomplish this, we will use a rat model (1) to characterize the effect of kainic acid on mechanical nociception using von Frey fibers and grip force; (2) determine whether the content of NGF and GDNF (immunoreactivity) or its receptors (binding) are affected by treatment with kainic acid; (3) to determine whether the application of exogenous NGF or GDNF is sufficient to increase mechanical nociception; (4) to determine whether there is a change in the density of SP- or NkiR immunoreactivity and/or the density of TMPase in the spinal cord or DRG after injection of NGF or GDNF; and (5) to determine whether injection of kainic acid alters either the density of SP- or NKiR-immunoreactivity in the spinal cord or DRG, in a fashion that correlates with its ability to induce mechanical hyperalgesia. These studies will determine whether kainic acid alters neurotrophic activity and nociceptive responses in the rat in a fashion that is consistent with the biochemical and sensory characteristics of FMS. If kainic acid activity proves to be a useful model of FMS, therapeutic options may be more readily developed for this disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS039740-03
Application #
6394320
Study Section
Special Emphasis Panel (ZAR1-BHD-B (J1))
Program Officer
Kitt, Cheryl A
Project Start
1999-07-26
Project End
2004-03-31
Budget Start
2001-07-01
Budget End
2002-06-30
Support Year
3
Fiscal Year
2001
Total Cost
$264,485
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Kovacs, Katalin J; Papic, Jonathan C; Larson, Alice A (2008) Movement-evoked hyperalgesia induced by lipopolysaccharides is not suppressed by glucocorticoids. Pain 136:75-84
Taiwo, Oludare B; Russell, I Jon; Mignot, Emmanuel et al. (2007) Normal cerebrospinal fluid levels of hypocretin-1 (orexin A) in patients with fibromyalgia syndrome. Sleep Med 8:260-5
Kovacs, Katalin J; Larson, Alice A (2006) Mast cells accumulate in the anogenital region of somatosensory thalamic nuclei during estrus in female mice. Brain Res 1114:85-97
Taiwo, Oludare B; Kovacs, Katalin J; Larson, Alice A (2005) Chronic daily intrathecal injections of a large volume of fluid increase mast cells in the thalamus of mice. Brain Res 1056:76-84
Taiwo, Oludare B; Kovacs, Katalin J; Sun, Yanxi et al. (2005) Unilateral spinal nerve ligation leads to an asymmetrical distribution of mast cells in the thalamus of female but not male mice. Pain 114:131-40
Taiwo, Oludare B; Kovacs, Katalin J; Sperry, Lauren C et al. (2004) Naloxone-induced morphine withdrawal increases the number and degranulation of mast cells in the thalamus of the mouse. Neuropharmacology 46:824-35
Kehl, Lois J; Kovacs, Katalin J; Larson, Alice A (2004) Tolerance develops to the effect of lipopolysaccharides on movement-evoked hyperalgesia when administered chronically by a systemic but not an intrathecal route. Pain 111:104-15
Fang, Ming; Kovacs, Katalin J; Fisher, Lauralei L et al. (2003) Thrombin inhibits NMDA-mediated nociceptive activity in the mouse: possible mediation by endothelin. J Physiol 549:903-17
Tien, Duc; Ohara, Peter T; Larson, Alice A et al. (2003) Vagal afferents are necessary for the establishment but not the maintenance of kainic acid-induced hyperalgesia in mice. Pain 102:39-49
Velazquez, Ruben A; McCarson, Kenneth E; Cai, Yongjiu et al. (2002) Upregulation of neurokinin-1 receptor expression in rat spinal cord by an N-terminal metabolite of substance P. Eur J Neurosci 16:229-41

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