title: TNFα is required for the production of T-type Ca(2+) channel-dependent long-term potentiation in visual cortex.
abstract: Monocular deprivation produces depression and potentiation of visual responses evoked in visual cortical neurons by stimulation of deprived and nondeprived eyes, respectively, during the critical period of ocular dominance plasticity. Our previous studies suggested that T-type Ca(2+) channel-dependent long-term potentiation (LTP), induced by 2 Hz stimulation, mediates the potentiation of visual responses. However, it was proposed that the experience-dependent response potentiation is mediated by tumor necrosis factor-α (TNFα)-dependent homeostatic synaptic scaling but not by Hebbian synaptic plasticity, because the potentiation was absent in TNFα knockout (TNFα-KO) mice. In this study, we investigated whether TNFα is required for LTP induced by 2 Hz stimulation using visual cortical slices prepared from critical period mice and rats. The production of LTP was prevented by pharmacological blockade of TNFα in rats and mice. LTP production was also prevented by an inhibitor of TNFα-converting enzyme that converts membrane-bound TNFα to soluble TNFα. In TNFα-KO mice, LTP did not occur and was rescued by exogenous soluble TNFα. Soluble TNFα was required for LTP production only during a restricted time window soon after 2 Hz stimulation. These results strengthen the view that T-type Ca(2+) channel-dependent LTP contributes to the potentiation of nondeprived eye responses following monocular deprivation.
authors.affiliation: Department of Neuroscience, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Sugimura
authors.affiliation: Division of Visual Information Processing, National Institute for Physiological Sciences, National Institutes for Natural Sciences, Okazaki 444-8585, Japan; Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Yoshimura
authors.affiliation: Department of Neuroscience, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan. Electronic address: komatsu@riem.nagoya-u.ac.jp.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Komatsu
mesh_terms: D000818:Animals; D020747:Calcium Channels, T-Type / Q000502:physiology*; D003423:Critical Period, Psychological; D023882:Dominance, Ocular; D004558:Electric Stimulation; D017774:Long-Term Potentiation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051381:Rats; D020318:Rats, Long-Evans; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*
chemical_list: D020747:Calcium Channels, T-Type; D014409:Tumor Necrosis Factor-alpha
keywords: Experience-dependent development; Long-term potentiation; Ocular dominance plasticity; T-type Ca(2+) channel; TNFα; Visual cortex