Acute augmentation of epoxygenated fatty acid levels rapidly reduces pain-related behavior in a rat model of type I diabetes.
The nerve damage occurring as a consequence of glucose toxicity in diabetes leads to neuropathic pain, among other problems. This pain dramatically reduces the quality of life in afflicted patients. The progressive damage to the peripheral nervous system is irreversible although strict control of hyperglycemia may prevent further damage. Current treatments include tricyclic antidepressants, anticonvulsants, and opioids, depending on the severity of the pain state. However, available therapeutics have drawbacks, arguing for the need to better understand the pathophysiology of neuropathic pain and develop novel treatments. Here we demonstrate that stabilization of a class of bioactive lipids, epoxygenated fatty acids (EpFAs), greatly reduces allodynia in rats caused by streptozocin-induced type I diabetes. Inhibitors of the soluble epoxide hydrolase (sEHI) elevated and stabilized the levels of plasma and spinal EpFAs, respectively, and generated dose-dependent antiallodynic effects more potently and efficaciously than gabapentin. In acute experiments, positive modulation of EpFAs did not display differences in insulin sensitivity, glucose tolerance, or insulin secretion, indicating the efficacy of sEHIs are not related to the glycemic status. Quantitative metabolomic analysis of a panel of 26 bioactive lipids demonstrated that sEHI-mediated antiallodynic effects coincided with a selective elevation of the levels of EpFAs in the plasma, and a decrease in degradation products coincided with the dihydroxy fatty acids in the spinal cord. Overall, these results argue that further efforts in understanding the spectrum of effects of EpFAs will yield novel opportunities in treating neuropathic pain.
Department of Entomology, University of California Davis and UC Davis Cancer Center, Davis, CA 95616, USA.
Bora
B
Inceoglu
Karen M
KM
Wagner
Jun
J
Yang
Ahmed
A
Bettaieb
Nils H
NH
Schebb
Sung Hee
SH
Hwang
Christophe
C
Morisseau
Fawaz G
FG
Haj
Bruce D
BD
Hammock
D000588:Amines / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy* / Q000378:metabolism; D004195:Disease Models, Animal; D015195:Drug Design; D005227:Fatty Acids / Q000378:metabolism*; D000077206:Gabapentin; D005947:Glucose / Q000378:metabolism; D006930:Hyperalgesia / Q000188:drug therapy*; D007328:Insulin / Q000378:metabolism; D008055:Lipids / Q000627:therapeutic use; D008297:Male; D008956:Models, Chemical; D010146:Pain / Q000188:drug therapy* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D000588:Amines; D003509:Cyclohexanecarboxylic Acids; D005227:Fatty Acids; D007328:Insulin; D008055:Lipids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D005947:Glucose