Proteinuric effect of transcranial magnetic stimulation in healthy subjects and diabetic patients with Stage 3-4 CKD.

BACKGROUND:
Many authors have investigated the numerous connections between the nervous system and kidneys, and recent literature has indicated that these similar systems are interconnected. Recent scientific works have shown that there is similarity between the cerebral cortex 'viscera representation' and the 'motor omunculus'. We studied the connection between the brain and kidney in vivo using repetitive transcranial magnetic stimulation (rTMS). Proteinuria and albuminuria were used as markers of renal response in patients with diabetes (DP) and in a group of healthy subjects (HSs) who received rTMS for 5 consecutive days.
METHODS:
The study population consists of the following four groups: Group A (HS stimulated), Group B (HS sham), Group C (DP stimulated) and Group D (DP sham). All subjects in Groups A and C underwent rTMS delivered at a frequency corresponding to 90% of the threshold at rest for 5 consecutive days. All subjects in Groups B and D underwent rTMS delivered with the coil placed on the scalp without delivering electromagnetic stimuli, while another coil at a distance of ∼2 m emitted stimuli at a very low intensity. This strategy ensured that brain stimulation would not occur, so that the subjects felt the vibrations produced by the click of the TMS coil. The proteinuria and albuminuria of 24 h and creatinine clearance were measured at time 0 (T0), after the first session (T1), at the end of the treatment (T5) and 24 h after the last stimulation (Post 24 h).
RESULTS:
In Group A, there was a statistically significant increase in albuminuria (5.65 ± 0.52 versus 12 ± 0.55 mg/24 h, P = 0.0001) and proteinuria (6.05 ± 0.48 versus 13.1 ± 0.60 mg/24 h, P = 0.0001) at the end of the treatment (T5) compared with the baseline values (T0). In Group C, the albuminuria was statistically higher at T5 than the baseline T0 (416.22 ± 181 versus 677.25 ± 280 mg/24 h, P = 0.04), as was proteinuria (561.37 ± 86 versus 865.125 ± 104 mg/24 h, P = 0.0001); in Group C, the increase in albuminuria (T0 versus post 24 h, P = 0.02) and proteinuria (T0 versus 24 h post, P = 0.0002) persisted at 24 h post. In Groups B and D, statistically significant changes were not found in proteinuria (Group B T0 versus T5, P = 0.61; Group D: T0 versus T5, P = 0.66) and albuminuria (Group B T0 versus T5, P = 0.15; Group D T0 versus T5, P = 0.44) measured at the same times.
CONCLUSIONS:
Consecutive rTMS is able to induce a statistically significant increase in albuminuria and proteinuria in HS and DP. A functional link between the brain and kidney is possible. For the first time, the results have indicated an increase of proteinuria in subjects undergoing transcranial stimulation.
KEYWORDS:
brain, brain stimulation, glomerular filtration barrier, kidney, proteinuria

PMID: 24319014