Effects of electrical stimulation of dorsal raphe nucleus on neuronal response properties of barrel cortex layer IV neurons following long-term sensory deprivation

Transplantation of rat dental pulp stem cells facilities post-lesion recovery in the somatosensory whisker cortex of male Wistar rats

Damage to somatosensory "barrel" cortex reduces the rats' behavioral sensitivity in discrimination of tactile stimuli. Here, we examined how transplantation of stem cells into the lesioned barrel cortex can help in recovery of sensory capacities. We induced mechanical lesions in the right barrel cortex area of male rats. Three days after lesioning, rats received one of three transplantation types: un-differentiated dental pulp stem cells (U-DPSCs) or differentiated dental pulp stem cells (D-DPSCs), or cell medium (vehicle). A fourth group of rats were control without any Surgery. For 4 consecutive weeks, starting one week after transplantation, we evaluated the rats' preference to explore novel textures as a measure of sensory discrimination ability, also measured the expression of glial fibrillary acidic protein (GFAP), Olig 2, nestin, neuronal nuclei (NeuN), brain-derived neurotrophic factor (BDNF) and neuroligin1 by immunohistochemistry and western blotting. Unilateral mechanical lesion decreased the rats' preferential exploration of novel textures compared to the control group across the 4-week behavioral tests. Following stem cell therapy, the rats' performance significantly improved at week 2-4 compared to the vehicle group. Compared to the control group, there was a significant decrease in the expression of nestin, NeuN, Olig 2, BDNF, neuroligin1 and a significant increase in the expression of GFAP in the vehicle group. The expression of the neural markers was significantly higher in DPSCs compared with the vehicle group whereas GFAP level was lower in DPSCs compared to vehicle. We found that DPSCs therapy affected a range of neuronal markers in the barrel cortex post lesion, and improved the rats' recovery for sensory discrimination.

Early antipsychotic treatment in juvenile rats elicits long-term alterations to the adult serotonin receptors

BACKGROUND

Antipsychotic drug (APD) prescription/use in children has increased significantly worldwide, despite limited insight into potential long-term effects of treatment on adult brain functioning. While initial long-term studies have uncovered alterations to behaviors following early APD treatment, further investigations into potential changes to receptor density levels of related neurotransmitter (NT) systems are required.

METHODS

The current investigation utilized an animal model for early APD treatment with aripiprazole, olanzapine, and risperidone in male and female juvenile rats to investigate potential long-term changes to the adult serotonin (5-HT) NT system. Levels of 5-HT1A, 5-HT2A, and 5-HT2C receptors were measured in the prefrontal cortex (PFC), caudate putamen (CPu), nucleus accumbens (NAc), and hippocampus via Western Blot and receptor autoradiography.

RESULTS

In the male cohort, long-term changes to 5-HT2A and 5-HT2C receptors were found mostly across hippocampal and cortical brain regions following early aripiprazole and olanzapine treatment, while early risperidone treatment changed 5-HT1A receptor levels in the NAc and PFC. Lesser effects were uncovered in the female cohort with aripiprazole, olanzapine and risperidone to alter 5-HT1A and 5-HT2A receptors in NAc and hippocampal brain regions, respectively.

CONCLUSION

The results of this study suggest that early treatment of various APDs in juvenile rats may cause gender and brain regional specific changes in 5-HT2A and 5-HT2C receptors in the adult brain.

The pattern of thalamocortical and brain stem projections to the vibrissae-related sensory and motor cortices in de-whiskered congenital hypothyroid rats

The present study is designed to investigate the plastic organization of the thalamo-cortical (TC) and brain stem afferents of whisker primary sensory (wS1) and motor (wM1) cortical areas in congenital hypothyroid (CH) pups following whisker deprivation (WD) from neonatal to adolescence period. Maternal hypothyroidism was induced by adding propylthiouracil (PTU) to the drinking water from early embryonic day 16 to postnatal day (PND) 60. Pregnant rats were divided into intact and CH groups (n = 8). In each group, the total whiskers of pups (4 of 8) were trimmed continuously from PND 1 to PND 60. Retrograde tracing technique with WGA-HRP was performed in the present study. Retrogradely labeled neurons were observed in the specific thalamic nuclei (VPM and VL) following separately WGA-HRP injections into wS1/M1 cortical areas. The number of labeled cells in the VPM, VL, VM and PO nuclei of the thalamus significantly decreased in CH offsprings rats (P < 0.05). Neonatal WD did not show any significant effects on the number of VPM, VL, VM and PO labeled projection neurons to wS1 and wM1 cortical areas. In addition, retrogradely labeled neurons in dorsal raphe (DR) and locus coeruleus (LC) nuclei were observed in all experimental groups. The number of DR and LC labeled neurons were higher in the CH and whisker deprived groups compared to their matching controls (P < 0.05). Upon our results, CH and WD had no synergic or additive effects on the TC and brain stem afferent patterns of barrel sensory and motor cortices.

Interactive Effects Between Exercise and Serotonergic Pharmacotherapy on Cortical Reorganization After Spinal Cord Injury

BACKGROUND

In rat models of spinal cord injury, at least 3 different strategies can be used to promote long-term cortical reorganization: (1) active exercise above the level of the lesion; (2) passive exercise below the level of the lesion; and (3) serotonergic pharmacotherapy. Whether and how these potential therapeutic strategies-and their underlying mechanisms of action-interact remains unknown. Methods In spinally transected adult rats, we compared the effects of active exercise above the level of the lesion (treadmill), passive exercise below the level of the lesion (bike), serotonergic pharmacotherapy (quipazine), and combinations of the above therapies (bike+quipazine, treadmill+quipazine, bike+treadmill+quipazine) on long-term cortical reorganization (9 weeks after the spinal transection). Cortical reorganization was measured as the percentage of cells recorded in the deafferented hindlimb cortex that responded to tactile stimulation of the contralateral forelimb. Results Bike and quipazine are "competing" therapies for cortical reorganization, in the sense that quipazine limits the cortical reorganization induced by bike, whereas treadmill and quipazine are "collaborative" therapies, in the sense that the reorganization induced by quipazine combined with treadmill is greater than the reorganization induced by either quipazine or treadmill.

CONCLUSIONS

These results uncover the interactive effects between active/passive exercise and serotonergic pharmacotherapy on cortical reorganization after spinal cord injury, emphasizing the importance of understanding the effects of therapeutic strategies in spinal cord injury (and in other forms of deafferentation) from an integrated system-level approach.