Activity-dependent changes in cortical protein expression may mediate long-term physiological processes such as sleep and neural connectivity. In this study we determined the number of nerve growth factor (NGF)-and interleukin-1β (IL1β)-immunoreactive (IR) cells in the somatosensory cortex (Sctx) in response to 2 h of mystacial whisker stimulation. Manual whisker stimulation for 2 h increased the number of NGF-IR cells within layers II-V in activated Sctx columns, identified by enhanced Fos-IR. IL1β-IR neurons increased within layers II-III and V-VI in these activated columns and IL1β-IR astrocytes increased in layers I, II-III and V as well as the external capsule beneath the activated columns. These whisker-stimulated increases in the Sctx did not occur in the auditory cortex. These data demonstrate that expression of NGF or IL1β in Sctx neurons and IL1β in Sctx astrocytes is, in part, afferent input-dependent.

Sensory input to different cortical areas differentially varies across the light-dark cycle and likely is responsible, in part, for activity-dependent changes in time-of-day differences in protein expression such as Fos In this study we investigate time-of-day differences between dark (just before light onset) and light (just before dark onset) for the number of immunoreactive (IR) neurons that stained for tumor necrosis factor alpha (TNFα), interleukin-1β (IL1β), nerve growth factor (NGF), the neuronal nuclear protein (NeuN) and Fos in the rat somatosensory cortex (Sctx) and visual cortex (Vctx).