Repetitive transcranial magnetic stimulation (rTMS) is a form of non-invasive brain
stimulation frequently used to induce neuroplasticity in the brain. Even at low intensities,
rTMS has been shown to modulate aspects of neuronal plasticity such as motor learning
and structural reorganisation of neural tissue. However, the impact of low intensity
rTMS on glial cells such as astrocytes remains largely unknown. This study investigated
changes in RNA (qPCR array: 125 selected genes) and protein levels (immunofluorescence)
in cultured mouse astrocytes following a single session of low intensity repetitive
magnetic stimulation (LI-rMS - 18 mT). Purified neonatal cortical astrocyte cultures
were stimulated with either 1Hz (600 pulses), 10Hz (600 or 6000 pulses) or sham (0
pulses) LI-rMS, followed by RNA extraction at 5 h post-stimulation, or fixation at
either 5 or 24-h post-stimulation. LI-rMS resulted in a two-to-four-fold downregulation
of mRNA transcripts related to calcium signalling (Stim1 and Orai3), inflammatory
molecules (Icam1) and neural plasticity (Ncam1). 10Hz reduced expression of Stim1,
Orai3, Kcnmb4, and Ncam1 mRNA, whereas 1Hz reduced expression of Icam1 mRNA and signalling-related
genes. Protein levels followed a similar pattern for 10Hz rMS, with a significant
reduction of STIM1, ORAI3, KCNMB4, and NCAM1 protein compared to sham, but 1Hz increased
STIM1 and ORAI3 protein levels relative to sham. These findings demonstrate the ability
of 1Hz and 10Hz LI-rMS to modulate specific aspects of astrocytic phenotype, potentially
contributing to the known effects of low intensity rTMS on excitability and neuroplasticity.