Adult Neurogenesis in Injury-Induced Self-Repair: Use It or Lose It

Functional Activation of Newborn Neurons Following Alcohol-Induced Reactive Neurogenesis

Abstinence after alcohol dependence leads to structural and functional recovery in many regions of the brain, especially the hippocampus. Significant increases in neural stem cell (NSC) proliferation and subsequent "reactive neurogenesis" coincides with structural recovery in hippocampal dentate gyrus (DG). However, whether these reactively born neurons are integrated appropriately into neural circuits remains unknown. Therefore, adult male rats were exposed to a binge model of alcohol dependence. On day 7 of abstinence, the peak of reactive NSC proliferation, rats were injected with bromodeoxyuridine (BrdU) to label dividing cells. After six weeks, rats underwent Morris Water Maze (MWM) training then were sacrificed ninety minutes after the final training session. Using fluorescent immunohistochemistry for c-Fos (neuronal activation), BrdU, and Neuronal Nuclei (NeuN), we investigated whether neurons born during reactive neurogenesis were incorporated into a newly learned MWM neuronal ensemble. Prior alcohol exposure increased the number of BrdU+ cells and newborn neurons (BrdU+/NeuN+ cells) in the DG versus controls. However, prior ethanol exposure had no significant impact on MWM-induced c-Fos expression. Despite increased BrdU+ neurons, no difference in the number of activated newborn neurons (BrdU+/c-Fos+/NeuN+) was observed. These data suggest that neurons born during alcohol-induced reactive neurogenesis are functionally integrated into hippocampal circuitry.

Postnatal neural crest stem cells from hair follicle interact with nerve tissue in vitro and in vivo

Neural crest stem cells that located in the postnatal hair follicle (HF-NCSC) are considered a promising tool for treatment of nervous system diseases and injuries. It is well known that HF-NCSC can be used in the spinal cord and sciatic nerve reparation but their ability to restore brain structures is poorly studied. In this article we are investigating the interaction between HF-NCSC and a nerve tissue (embryonic and adult). We have found out that HF-NCSC isolated from adult mice grow and differentiate in accordance with the mouse embryo developmental stage when co-cultured with the embryonic nerve tissue. The HF-NCSC migration is slower in the late embryonic tissue co-culture system compared to the early one. This phenomenon is related to the motor function of the cells but not to their proliferation level. We have demonstrated that the embryonic nerve tissue maintains HF-NCSC an undifferentiated status, while an adult brain tissue inhibits the cell proliferation and activates the differentiation processes. Besides, HF-NCSC pre-differentiated into the neuronal direction shows a higher survival and migration rate after the transplantation into the adult brain tissue compared to the undifferentiated HF-NCSC. Thus, we have investigated the postnatal HF-NCSC response to the nerve tissue microenvironment to analyze their possible application to the brain repair processes.