Christine Ayoola1, Sung Mi Hwang1,2, Sung Jun Hong1,3, Kirstin E Rose1, Christopher Boyd1, Neda Bozic1, Ji-Yong Park4, Hari Prasad Osuru1, Michael R DiGruccio1,5, Douglas F Covey6, Vesna Jevtovic-Todorovic1,7,5, Slobodan M Todorovic1,7,5. 1. Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA. 2. Department of Anesthesiology and Pain Medicine, Chuncheon Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Republic of Korea. 3. Department of Anesthesiology and Pain Medicine, Kangdong Sacred Heart Hospital, College of Medicine, Hallym University Seoul, Republic of Korea. 4. Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Republic of Korea. 5. Department of Neuroscience Graduate Program, University of Virginia Health System, Charlottesville, VA. 6. Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO. 7. Department of Neuroscience, University of Virginia Health System, Charlottesville, VA.
Abstract
RATIONALE: T-type calcium channels (T-channels) play an important role in controlling excitability of nociceptors. We have previously shown that a synthetic series of 5β-reduced steroids induce a voltage-dependent blockade of T-currents in rat dorsal root ganglia (DRG) cells in vitro and induce potent analgesia to thermal stimuli in rats in vivo (Mol Pharmacol 66:1223-1235, 2004). OBJECTIVES: Here, we investigated the effects of the endogenous 5β-reduced neuroactive steroid molecule, epipregnanolone [(3β,5β)-3-hydroxypregnan-20-one], on peripheral nociception. METHODS: We used acutely dissociated DRG cells in vitro from adult rats as well as in vivo pain studies in mice and rats to investigate the effects of epipregnanolone on DRG T-channels. RESULTS: We found that epipregnanolone reversibly blocked DRG T-currents with a half-maximal inhibitory concentration (IC50) of 2 μM and stabilized the channel in the inactive state. However, sodium, potassium, and gamma-aminobutyric acid (GABA)-gated ionic currents were not sensitive to the blocking effects of epipregnanolone even at 10 μM. In ensuing in vivo studies, we found that intraplantar (i.pl.) injections of epipregnanolone directly into peripheral receptive fields reduced responses to nociceptive heat stimuli in rats in a dose-dependent fashion. Furthermore, i.pl. epipregnanolone injections effectively reduced responses to peripheral nociceptive thermal and mechanical stimuli in wild-type mice but had no effect on the responses of CaV3.2 knockout mice. CONCLUSIONS: We conclude that the inhibition of peripheral CaV3.2 T-channels contributes to the potent analgesic effect of the endogenous steroid epipregnanolone.
RATIONALE: T-type calcium channels (T-channels) play an important role in controlling excitability of nociceptors. We have previously shown that a synthetic series of 5β-reduced steroids induce a voltage-dependent blockade of T-currents in rat dorsal root ganglia (DRG) cells in vitro and induce potent analgesia to thermal stimuli in rats in vivo (Mol Pharmacol 66:1223-1235, 2004). OBJECTIVES: Here, we investigated the effects of the endogenous 5β-reduced neuroactive steroid molecule, epipregnanolone [(3β,5β)-3-hydroxypregnan-20-one], on peripheral nociception. METHODS: We used acutely dissociated DRG cells in vitro from adult rats as well as in vivo pain studies in mice and rats to investigate the effects of epipregnanolone on DRG T-channels. RESULTS: We found that epipregnanolone reversibly blocked DRG T-currents with a half-maximal inhibitory concentration (IC50) of 2 μM and stabilized the channel in the inactive state. However, sodium, potassium, and gamma-aminobutyric acid (GABA)-gated ionic currents were not sensitive to the blocking effects of epipregnanolone even at 10 μM. In ensuing in vivo studies, we found that intraplantar (i.pl.) injections of epipregnanolone directly into peripheral receptive fields reduced responses to nociceptive heat stimuli in rats in a dose-dependent fashion. Furthermore, i.pl. epipregnanolone injections effectively reduced responses to peripheral nociceptive thermal and mechanical stimuli in wild-type mice but had no effect on the responses of CaV3.2 knockout mice. CONCLUSIONS: We conclude that the inhibition of peripheral CaV3.2 T-channels contributes to the potent analgesic effect of the endogenous steroid epipregnanolone.
Authors: Mingde Wang; Yejun He; Lawrence N Eisenman; Christopher Fields; Chun-Min Zeng; Jose Mathews; Ann Benz; Tao Fu; Erik Zorumski; Joe Henry Steinbach; Douglas F Covey; Charles F Zorumski; Steven Mennerick Journal: J Neurosci Date: 2002-05-01 Impact factor: 6.167
Authors: Charles F Zorumski; Steven M Paul; Yukitoshi Izumi; Douglas F Covey; Steven Mennerick Journal: Neurosci Biobehav Rev Date: 2012-10-17 Impact factor: 8.989
Authors: Janelle R Latham; Sriyani Pathirathna; Miljen M Jagodic; Won Joo Choe; Michaela E Levin; Michael T Nelson; Woo Yong Lee; Kathiresan Krishnan; Douglas F Covey; Slobodan M Todorovic; Vesna Jevtovic-Todorovic Journal: Diabetes Date: 2009-08-03 Impact factor: 9.461
Authors: Sonja L Joksimovic; Srdjan M Joksimovic; Vesna Tesic; Agustin García-Caballero; Simon Feseha; Gerald W Zamponi; Vesna Jevtovic-Todorovic; Slobodan M Todorovic Journal: Sci Signal Date: 2018-08-28 Impact factor: 8.192
Authors: Tal Hoffmann; Katrin Kistner; Sonja L J Joksimovic; Slobodan M Todorovic; Peter W Reeh; Susanne K Sauer Journal: Exp Neurol Date: 2021-08-25 Impact factor: 5.330
Authors: Quy L Tat; Srdjan M Joksimovic; Kathiresan Krishnan; Douglas F Covey; Slobodan M Todorovic; Vesna Jevtovic-Todorovic Journal: Cells Date: 2020-12-12 Impact factor: 6.600
Authors: Sonja L Joksimovic; Douglas F Covey; Vesna Jevtovic-Todorovic; Slobodan M Todorovic Journal: Front Pharmacol Date: 2018-10-02 Impact factor: 5.810