Neonatal Tactile Stimulation Modulates Dendritic Spine Densities in Somatosensory Cortex of Adult WAG/Rij rats

Objective: The aim of our study is to examine the effects of neonatal tactile stimulatons on the brain structures that previously defined as the focus of epilepsy in the Wistar-Albino-Glaxo from Rijswijk (WAG/Rij) rat brain with genetic absence epilepsy.Methods: In the present research, morphology and density of dendritic spines were analyzed in the somatosensory cortex (SoCx) of WAG/Rij rats (non stimulated control, tactile-stimulated and maternal separated rats) and healthy Wistar (non-epileptic) rats. To achieve this, a Golgi-Cox method was used.Results: Dendritic spine number in layer V of the SoCx has been detected significantly higher in adult WAG/Rij rats at post natal day 150 in comparison to non-epileptic adult control Wistar rats (p<0,001). Moreover, quantitative analyses of dendrite structure in adult WAG/Rij rats showed a decrease in dendrite spine density of pyramidal neurons of SoCx which occurred in early neonatal exposure to maternal separation (MS) and tactile stimulation (TS) (p<0,001).Conclusions: Our findings provide the first evidence that tactile stimulations during the early postnatal period have a long-term impact on dendrite structure in WAG/Rij rat’s brain and suggest a reduction in dendrite spine density is linked to absence seizure reduction.

Neonatal Tactile Stimulation Modulates Dendritic Spine Densities in Somatosensory Cortex of Adult WAG/Rij rats

Objective: The aim of our study is to examine the effects of neonatal tactile stimulatons on the brain structures that previously defined as the focus of epilepsy in the Wistar-Albino-Glaxo from Rijswijk (WAG/Rij) rat brain with genetic absence epilepsy.Methods: In the present research, morphology and density of dendritic spines were analyzed in the somatosensory cortex (SoCx) of WAG/Rij rats (non stimulated control, tactile-stimulated and maternal separated rats) and healthy Wistar (non-epileptic) rats. To achieve this, a Golgi-Cox method was used.Results: Dendritic spine number in layer V of the SoCx has been detected significantly higher in adult WAG/Rij rats at post natal day 150 in comparison to non-epileptic adult control Wistar rats (p<0,001). Moreover, quantitative analyses of dendrite structure in adult WAG/Rij rats showed a decrease in dendrite spine density of pyramidal neurons of SoCx which occurred in early neonatal exposure to maternal separation (MS) and tactile stimulation (TS) (p<0,001).Conclusions: Our findings provide the first evidence that tactile stimulations during the early postnatal period have a long-term impact on dendrite structure in WAG/Rij rat’s brain and suggest a reduction in dendrite spine density is linked to absence seizure reduction.

Neonatal Tactile Stimulation Modulates Dendritic Spine Densities in Somatosensory Cortex of Adult WAG/Rij rats

Background In previous studies, it has been shown that in early developmental period, the high level of tactile stimulations prevent absence epilepsy development and comorbid depression in Wistar-Albino-Glaxo from Rijswijk (WAG/Rij) rats with absence epilepsy. The aim of our study is to examine the effects of neonatal tactile stimulatons on the brain structures that previously defined as the focus of epilepsy in the rat brain with genetic absence epilepsy. Results In the present research, morphology and density of dendritic spines were analyzed in the somatosensory cortex (SoCx) in WAG/Rij rats with absence epilepsy, sensory experienced WAG/Rij rats (tactile-stimulated and maternal separated) and healthy Wistar (non-epileptic) rats. To achieve this, a Golgi-Cox method was used. Dendritic spine number in layer V of the SoCx has been detected significantly higher in adult WAG/Rij rats at post natal day 150 in comparison to non-epileptic adult control Wistar rats (p < 0,001). Moreover, quantitative analyses of dendrite structure in adult WAG/Rij rats showed a decrease in dendrite spine density of pyramidal neurons of SoCx which occurred in early neonatal exposure to maternal separation (MS) and tactile stimulation (TS) (p < 0,001). Conclusions Our findings provide the first evidence that tactile stimulations during the early postnatal period have a long-term impact on dendrite structure in WAG/Rij rat’s brain and suggest a reduction in dendrite spine density is linked to absence seizure reduction.

Neuregulin-4 Is Required for the Growth and Elaboration of Striatal Medium Spiny Neuron Dendrites

Medium spiny neurons (MSNs) comprise the vast majority of neurons in the striatum. Changes in the exuberant dendrites of these widely connected neurons are associated with a multitude of neurological conditions and are caused by a variety of recreational and medicinal drugs. However, we have a poor understanding of the physiological regulators of dendrite growth and elaboration of this clinically important population of neurons. Here, we show that MSN dendrites are markedly smaller and less branched in neonatal mice that possess a homozygous null mutation in the neuregulin-4 gene (Nrg4−/−) compared with wild type (Nrg4+/+) littermates. Nrg4−/− mice also had a highly significant reduction in MSN dendrite spine number in neonates and adults. The striking stunted dendrite arbor phenotype of MSNs observed in Nrg4−/− neonates was replicated in MSNs cultured from Nrg4−/− embryos and was completely rescued by soluble recombinant neuregulin-4. MSNs cultured from wild type mice coexpressed NRG4 and its receptor ErbB4. Our findings show that NRG4 is a major novel regulator of dendritic growth and arborization and spine formation in the striatum and suggest that it exerts its effects by an autocrine/paracrine mechanism.