Journal of neurophysiology
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1. This study examines the effect on auditory desensitization of electrically stimulating the crossed olivocochlear bundle (COCB) at the floor of the fourth ventricle. Auditory desensitization was induced by a loud high-frequency pure tone exposure and measured as temporary threshold shifts (TTS) in the sensitivity of the compound action potential recorded from the cochlea. ⋯ However, if the persistent effect was at a more central location, lesioning the fibers would allow afferent input to act at the facilitated central location but would not allow subsequent expression of COCB effects at the cochlea. In this case, no reductions in TTS could be expected--precisely the results that were obtained in these experiments. Thus the COCB system appeared to have a "memory" component facilitated by prior stimulation and activated by a subsequent exposure.
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1. We have recently shown that leukotriene B4 (LTB4), a product of the 5-lipoxygenase pathway of arachidonic acid metabolism, sensitizes nociceptors to mechanical stimuli. The present study examined whether LTB4 also induces a heat sensitization of cutaneous C-fiber nociceptors. ⋯ The magnitude of the LTB4-evoked decrease in thermal threshold was similar to that produced by 75 ng of prostaglandin E2 (PGE2). These data demonstrate that LTB4 sensitizes C-mechanoheat nociceptors to both mechanical and thermal stimuli. 4. We conclude that LTB4 may contribute to the component of hyperalgesia that is resistant to nonsteroidal anti-inflammatory agents.