Induced Dipoles and Possible Modulation of Wireless Effects in Implanted Electrodes. Effects of Implanting Insulated Electrodes on an Animal Test to Screen Antidepressant Activity

There is evidence that Deep Brain Stimulation (DBS) produces health benefits in patients even before initiating stimulation. Furthermore, DBS electrode insertion in rat infralimbic cortex (ILC) provokes antidepressant-like effects before stimulation, due to local inflammation and astrogliosis. Consequently, a significant effect of implanting electrodes is suspected. External fields, similar in magnitude to the brain's endogenous fields, induce electric dipoles in conducting materials, in turn influencing neural cell growth through wireless effects. To elucidate if such dipoles influence depressive-like behavior, without external stimulation, the comparative effect of conducting and insulated electrodes along with the glial response is studied in unstressed rats. Naive and implanted rats with electrically insulated or uninsulated steel electrodes were evaluated in the modified forced swimming test and expression of ILC-glial markers was assessed. An antidepressant-like effect was observed with conducting but not with insulated electrodes. Gliosis was detected in both groups, but astroglial reactivity was larger near uninsulated electrodes. Thus, induced dipoles and antidepressant-like effects were only observed with conducting implants. Such correlation suggests that dipoles induced in electrodes by endogenous fields in turn induce neuron stimulation in a feedback loop between electrodes and neural system. Further research of the effects of unwired conducting implants could open new approaches to regulating neuronal function, and possibly treat neurological disorders.This study was also supported by grants co-financed by the "Fondo Europeo de Desarrollo Regional" (FEDER)-UE "A way to build Europe" from the "Ministerio de Economia y Competitividad" (MINECO: RTI2018-099778-B-I00 (to E.B.), RTI2018-098269-B-I00 (to J.N.) and RTI2018-097753-B-I00 (to N.C.P.) and "Juan de la Cierva Formacion" postdoctoral grant FJC2018-037958-I (to L.P.C.)) and PID2019-108562GB-I00 (to V.T.M); the "Consejeria de Economia, Innovacion, Ciencia y Empleo de la Junta de Andalucia" (CTS-510, to E.B.); the Severo Ochoa Program CEX2019-000917-S (to N.C.P.) and the "Centro de Investigacion Biomedica en Red de Salud Mental-CIBERSAM" (CB/07/09/0033 and CB/07/09/0006

Induced Dipoles and Possible Modulation of Wireless Effects in Implanted Electrodes. Effects of Implanting Insulated Electrodes on an Animal Test to Screen Antidepressant Activity

There is evidence that Deep Brain Stimulation (DBS) produces health benefits in patients even before initiating stimulation. Furthermore, DBS electrode insertion in rat infralimbic cortex (ILC) provokes antidepressant-like effects before stimulation, due to local inflammation and astrogliosis. Consequently, a significant effect of implanting electrodes is suspected. External fields, similar in magnitude to the brain’s endogenous fields, induce electric dipoles in conducting materials, in turn influencing neural cell growth through wireless effects. To elucidate if such dipoles influence depressive-like behavior, without external stimulation, the comparative effect of conducting and insulated electrodes along with the glial response is studied in unstressed rats. Naïve and implanted rats with electrically insulated or uninsulated steel electrodes were evaluated in the modified forced swimming test and expression of ILC-glial markers was assessed. An antidepressant-like effect was observed with conducting but not with insulated electrodes. Gliosis was detected in both groups, but astroglial reactivity was larger near uninsulated electrodes. Thus, induced dipoles and antidepressant-like effects were only observed with conducting implants. Such correlation suggests that dipoles induced in electrodes by endogenous fields in turn induce neuron stimulation in a feedback loop between electrodes and neural system. Further research of the effects of unwired conducting implants could open new approaches to regulating neuronal function, and possibly treat neurological disorders.This study was also supported by grants co-financed by the “Fondo Europeo de Desarrollo Regional” (FEDER)-UE “A way to build Europe” from the “Ministerio de Economía y Competitividad” (MINECO: RTI2018-099778-B-I00 (to E.B.), RTI2018-098269-B-I00 (to J.N.) and RTI2018-097753- B-I00 (to N.C.P.) and “Juan de la Cierva Formación” postdoctoral grant FJC2018-037958-I (to L.P.C.)) and PID2019-108562GB-I00 (to V.T.M); the “Consejería de Economía, Innovación, Ciencia y Empleo de la Junta de Andalucía” (CTS-510, to E.B.); the Severo Ochoa Program CEX2019-000917-S (to N.C.P.) and the “Centro de Investigación Biomédica en Red de Salud Mental-CIBERSAM” (CB/07/09/0033 and CB/07/09/0006).Peer reviewe