TNF-A Levels throughout the Critical Period for Experience-Dependent Plasticity in the Rat Primary Auditory Cortex

Caroline Madeira,Wai Hong Man

doi:10.4172/2469-9780.1000105

Abstract

Tumor necrosis factor- alpha (TNF-α) is likely to play a role in brain plasticity. To determine whether TNF-α levels change throughout a critical period of experience-dependent brain plasticity, we assessed these levels in the primary auditory cortex of rats before, during and after the critical period (at postnatal day 7, postnatal day 12 and at adulthood, respectively). TNF-α levels in the auditory cortex increased from before to after a critical period of brain plasticity. We suggest that TNF-α may play a role in the brain plasticity that occurs in the auditory cortex.

Highlights

Tumor necrosis factor- alpha (TNF-α) is a well-studied cytokine that acts as an important central mediator in the on-set of inflammatory cascade and exerts anti-tumoral activity [1]
We found that mean TNF-α levels in the primary auditory cortex increase throughout the critical period, from 71.13 pg/g protein (SD=29.63; N=6) at P7, to 92.84 pg/g protein (SD=23.16; N=5) at P12, and to 119.8 pg/g protein (SD=23.58; N=6) at P30
In contrast to the increase observed in the auditory cortex, TNF-α levels in the frontal cortex showed a tendency to decrease over the same time window: they went from 29.56 pg/g protein (SD=10.62; N=3) at P7 to 14.14 pg/g protein (SD=2.16; N=3) at P12, and to 17.08 pg/g protein (SD=3.13; N=3) in P30

Summary

Introduction

Tumor necrosis factor- alpha (TNF-α) is a well-studied cytokine that acts as an important central mediator in the on-set of inflammatory cascade and exerts anti-tumoral activity [1]. It was shown that TNF-α mediates homeostatic synaptic scaling in response to prolonged blockade of activity [7,8,9]. Homeostatic synaptic scaling mediated by TNF-α participates in experience-dependent brain plasticity [11]. Kaneko et al described that experience-dependent plasticity in the developing visual cortex involves a homeostatic increase in responses, which is dependent on TNF-α signaling. To determine the onset and duration of the critical period of experience-dependent plasticity in the primary auditory cortex, rat pups were exposed to pure-tones at different postnatal ages. We document changes in TNF-α from before to after the critical period of experience-dependent plasticity in the primary auditory cortex. We measured the TNF-α levels in the frontal cortex at the same ages

Methods

Results

Conclusion