Tactile sensory input regulates basal and apomorphine‐induced immediate‐early gene expression in rat barrel cortex

Abstract

Clipping of mystacial vibrissae on one side of the rat's snout results in sensorimotor asymmetries in normal behavior and in behavior induced by the dopamine receptor agonist, apomorphine. Immediate-early gene expression, a marker for short-term changes in neuron function, was used to examine whether this sensory deprivation leads to functional changes in the somatosensory barrel cortex under experimental conditions which reveal behavioral asymmetries. The expression of c-fos and zif268 immediate-early genes was assessed with in situ hybridization histochemistry. Four hours after unilateral clipping of the mystacial vibrissae, the level of zif268 mRNA was reduced in the corresponding part of the contralateral barrel field. Injection of apomorphine (5 mg/kg) resulted in increased expression of both c-fos and zif268 immediate-early genes in cortex and striatum. This apomorphine-induced increase was blocked in the sensory-deprived somatosensory cortex. Laminar analysis of gene regulation showed that vibrissae removal affected immediate-early gene expression in all layers of the barrel cortex. These results demonstrate that: (1) basal zif268 gene expression in neurons of the somatosensory cortex is dependent on sensory input, (2) cortical immediate-early gene expression is increased after dopamine receptor activation, and (3) in the barrel cortex, this increase is also dependent on sensory input. We suggest that the observed reduction in gene expression after vibrissae removal reflects decreased activation of neurons in the barrel column by removal of sensory input.

Differential Effects of Abnormal Tactile Experience on Shaping Representation Patterns in Developing and Adult Motor Cortex

“…The basis for such effects could be long-term changes in synapse number as a result of altered experience (K leim et al, 1996) or changes in synaptic efficacies of preexisting connections (Diamond et al, 1993;Donoghue et al, 1996) through long-term, activitydependent changes in neurochemical levels. In adult rodent S1, for example, enhancing or reducing activity by vibrissa stimulation or trimming leads to changes in levels of glutamic acid decarboxylase (Akhtar and Land, 1991), growth factors (Rocamora et al, 1996), and immediate-early genes (Steiner and Gerfen, 1994). The one novel change evident in the adulttrimmed group was a reduction in the proportion of dual forelimb-vibrissa sites along the common border.…”

Tactile Experience Induces c-fos Expression in Rat Barrel Cortex

“…Treatment of rats with apomorphine, a dopamine receptor agonist enhancing motor activity, results in the accumulation of c-fos and zif268 (the two best studied immediate early genes) mRNA in various brain regions including somatosensory cortex (Steiner and Gerfen 1994). This effect was apparently input specific, because clipping of the whiskers prevented the increase in the corresponding PMBSF.…”

Effects of acute and chronic apomorphine on sex behavior and copulation-induced neural activation in the male rat

“…The Barrel cortex contains D 1 receptors and its activation, as shown by an increase in immediate-early gene expression, is dependent on both sensory input from the vibrissae, as well as on dopaminergic receptor activation (Filipkowski et al, 2001;Steiner and Gerfen, 1994;Steiner and Kitai, 2000). The increase in Fos-immunoreactivity is most prominent in the deeper layers (4, 5 and 6) (Filipkowski et al, 2001) and concurs with the increased sniffing/whisking behavior, induced by apomorphine administration as well as by copulatory activities (Figs.…”

“…Changes in Fos-immunoreactivity after administration of apomorphine have been described as well (Cenci et al, 1992;Laudrup et al, 1997;Steiner and Gerfen, 1994;Wirtshafter, 2000). However, the effects of chronic administration of apomorphine on male rat sexual behavior, in combination with the changes in Fos-immunoreactivity patterns induced by apomorphine and copulatory behavior, have not been studied thus far.…”