Neonatal Tactile Stimulation Downregulates Dendritic Spines in Layer V Pyramidal Neurons of the WAG/Rij Rat Somatosensory Cortex

Abstract

Objective. The aim of our study is to examine the effects of neonatal tactile stimulations 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 layer V pyramidal neurons of the somatosensory cortex (SoCx) of WAG/Rij rats (nonstimulated control, tactile-stimulated, and maternal separated rats) and healthy Wistar (nonepileptic) 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 postnatal day 150 in comparison to nonepileptic 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 demonstrate that neonatal tactile stimulation can regulate dendritic spines in layer V in pyramidal neurons of SoCx in epileptic brains.

Tactile stimulation of young WAG/Rij rats prevents development of depression but not absence epilepsy

“…In a study done by our group we found that neonatal tactile stimulation slows down the development of absence epilepsy and comorbid depression-like symptoms in adult WAG/Rij rats ( Balikci et al, 2020 ). In our next study, we have shown that tactile stimulations during the early postnatal period have a long-term impact on dendrite structure in WAG/Rij rat’s brain, and neonatal tactile stimulation can regulate dendritic spines in layer V in pyramidal neurons of SoCx which previously defined as the focus of epilepsy ( Ilbay et al, 2022 ). Although there are exciting results showing the positive effects of enriching tactile experiences in early life on absence epilepsy and accompanying depression-like behaviors in WAG/Rij rats, research on the effects of tactile experiences later in life does not exist.…”

“…Then, an impartial evaluator assessed the duration of inactive swimming (immobility), the time it took for immobility to occur (immobility latency), and the overall amount of active swimming (swimming time) for each rat. Immobility is the state of being completely still, with no other movement save for the necessary action of keeping the head above water ( Balikci et al, 2020 ; Ilbay et al, 2022 ).…”

“…The values of sucrose consumption on the 4th day were utilized to assess the disparities across rat groups following a 3-day adaption technique, as outlined in prior research. The animals’ hedonic-like states were measured by sucrose consumption, while the number of approaches served as an indirect sign of exploratory activity during the test ( Balikci et al, 2020 ; Ilbay et al, 2022 ).…”

“…Recent experimental reports have demonstrated that there are successful therapies that have interfered with epileptogenesis ( Blumenfeld et al, 2008 ; Russo et al, 2010 ; Wong, 2010 ; McClelland et al, 2011 ; Balikci et al, 2020 ; Ilbay et al, 2022 ; Sarkisova and van Luijtelaar, 2022 ). Moreover, recent evidence for the effects of early life manipulations on the epileptic and behavioral phenotype of WAG/Rij rats supports the disease-modifying treatment notion ( Sarkisova and Gabova, 2018 ; Balikci et al, 2020 ; Ilbay et al, 2022 ; Sarkisova and van Luijtelaar, 2022 ).…”

“…Tactile stimulation is a form of social contact enrichment that improves sensory stimulation and results in neurobiological alterations that decrease anxiety and improve cognition and memory in rats ( Richards et al, 2012 ; Antoniazzi et al, 2014 ; Balikci et al, 2020 ; Ilbay et al, 2022 ). Studies have shown that tactile stimulation promotes changes in the brain’s structure and function, which helps to alleviate the negative effects of pathological processes ( Gibb et al, 2010 ; Richards et al, 2012 ; Costa et al, 2020 ; Ilbay et al, 2022 ).…”