Galvanic vestibular stimulation impairs cell proliferation and neurogenesis in the rat hippocampus but not spatial memory

Abstract

Galvanic vestibular stimulation (GVS) is a method of activating the peripheral vestibular system using direct current that is widely employed in clinical neurological testing. Since movement is recognized to stimulate hippocampal neurogenesis and movement is impossible without activation of the vestibular system, we speculated that activating the vestibular system in rats while minimizing movement, by delivering GVS under anesthesia, would affect hippocampal cell proliferation and neurogenesis, and spatial memory. Compared with the sham control group, the number of cells incorporating the DNA replication marker, bromodeoxyuridine (BrdU), was significantly reduced in the bilateral hippocampi in both the cathode left‐anode right and cathode right‐anode left stimulation groups (P ≤ 0.0001). The majority of the BrdU+ve cells co‐expressed Ki‐67, a marker for the S phase of the cell cycle, suggesting that these BrdU+ve cells were still in the cell cycle; however, there was no significant difference in the degree of co‐labeling between the two stimulation groups. Single labeling for doublecortin (DCX), a marker of immature neurons, showed that while there was no significant difference between the different groups in the number of DCX+ve cells in the right dentate gryus, in the left dentate gyrus there was a significant decrease in the cathode left‐anode right group compared with the sham controls (P ≤ 0.03). Nonetheless, when animals were tested in place recognition, object exploration and Morris water maze tasks, there were no significant differences between the GVS groups and the sham controls. These results suggest that GVS can have striking effects on cell proliferation and possibly neurogenesis in the hippocampus, without affecting spatial memory. © 2014 Wiley Periodicals, Inc.

Longitudinal Cognitive and Neurobehavioral Functional Outcomes Before and After Repairing Otic Capsule Dehiscence

“…Smith et al and Zheng et al reported that modulation of memory, but not spatial memory, occurs with vestibular lesions and can be influenced by galvanic vestibular stimulation ( 72 , 73 ). These findings may lead to additional treatment strategies that may accelerate or maximize recovery after repairing a no-iOCD or SCD.…”

Single neuron activity and c-Fos expression in the rat striatum following electrical stimulation of the peripheral vestibular system

“…The 10 min duration of stimulation used for the c‐Fos study was initially based on previous studies of the effects of galvanic vestibular stimulation on cell proliferation in the hippocampus (Zheng et al. ), as well as pilot data. It was assumed that briefer stimulation may not be sufficient to alter c‐Fos expression in the striatum.…”

“…This was done using a Dino‐Lite microscopic video camera focused on the rat's eye (Zheng et al. ), images from which were displayed on a PC. For each rat the threshold for nystagmus was defined as the lowest current at which eye movement was visible.…”

The effects of electrical stimulation of the peripheral vestibular system on neurochemical release in the rat striatum

“…A stainless-steel bipolar electrode (MS303/1-B/SPC, Plastics One Inc.), insulated except at the tip, was placed into the round window as the stimulating electrode. It was secured in place using dental cement once the location of the electrode placement was confirmed via visualisation of vestibular nystagmus in response to stimulation, which was considered evidence that the peripheral vestibular system was being adequately activated [ 12 , 39 ] ( Fig 1C ). The surgical site was then sutured closed.…”

“…The surgical site was then sutured closed. Eye movements were recorded using a Dino-Lite microscopic video camera focused on the rat’s eye [ 12 , 39 ], images from which were displayed on a PC monitor. The threshold for nystagmus was defined as the lowest current at which eye movement was visible ( Fig 2 ).…”