Favorable and unfavorable lactation modulates the effects of electrical stimulation on brain excitability: a spreading depression study in adult rats.

AIMS

We investigated how different nutritional states resulting from distinct lactation conditions modulate the effects of cortical electrical stimulation (CES) on the excitability-related phenomenon known as cortical spreading depression (CSD).

MAIN METHODS

Wistar rats were reared in different litter sizes with 12, 6 or 3 pups, designated as malnourished (M), well-nourished (W) and overnourished (Ov), respectively. CSD was recorded for 4h on 2 cortical points of each cerebral hemisphere at baseline and after CES. CES was applied for 20 min on the left cortex using a bipolar electrode placed between the CSD recording electrodes. Paired Student t test and ANOVA followed by Tukey test were used for statistical analysis (p<0.05).

KEY FINDINGS

The lactation conditions significantly influenced body weight (the M and Ov groups presented the lowest and largest average weight, respectively) and modified the CSD velocities of propagation in adulthood (Ov<W<M CSD velocity). CES increased CSD velocity of propagation in the stimulated hemisphere in all groups, and in the non-stimulated hemisphere (8.66%± 1.38) in the Ov group only. We observed nutritional-dependent CES effects on cortical excitability as evaluated by the different CSD velocities across the three groups (mean ± sem, M (10.13%± 1.70), Ov (14.65%± 1.10) and W (25.70%± 5.05)).

SIGNIFICANCE

These findings suggest valuable mechanisms of action for the brain stimulation techniques, which have gained importance because of their increasing use for the treatment of neuropsychiatric diseases. Data also suggest modulation of CES-effects by baseline excitability (as determined by the early nutritional state).