Long-term potentiation enhancing effect of epileptic insult in the CA1 area is dependent on prior-application of primed-burst stimulation.

Herein field recordings were utilized to test the effects of a transient period of pentylenetetrazol (PTZ) treatment on theta-burst long-term potentiation (LTP) at the Schaffer collateral-CA1 synapses as well as RT-PCR was used to investigate the effects of the combination of the pharmacological treatment and the theta-burst LTP induction on the expression of NMDA subunit mRNA in hippocampal slices. The slope of field excitatory postsynaptic potential (fEPSP) was unaffected while the population spike amplitude and area were increased by a transient period of PTZ treatment (3 mM, 10 min). After a theta burst, a brief PTZ exposure can lead to an enhancement of LTP as documented by fEPSP recording. The effect can be blocked by a selective NMDA receptor antagonist DL-AP5. An increase in the expression of GluN2B and GluN2A subunit mRNAs was also shown due to the combined treatment. The results indicate that the combined treatment increases the degree of NMDA-dependent LTP and are in accord with literature data on the subunit alterations of the hippocampal NMDA receptors. Moreover, our experimental paradigm can be used as a new approach to study the relevance of LTP-like phenomena and epileptic mechanisms.

Pre-pubertal castration improves spatial learning during mid-adolescence in rats.

Hippocampus functions, including spatial cognition and stress responses, mature during adolescence. In addition, hippocampus neuronal structures are modified by circulating sex steroids, which dramatically increase during adolescence. Therefore, the effects of castration and the circulating levels of the main sex steroid testosterone on spatial learning and memory were examined across postnatal ages to test whether pre-pubertal castration affected rats' spatial ability in the Morris Water maze (MWM). Male rats were either castrated or sham-castrated at 22d (days of age), or left gonadally intact. They were then trained and tested in the MWM beginning at 28d, 35d, 45d or 60d. We found that all of the intact rats learned the spatial task; however, the males at 22d and 28d required more trials to acquire the task than the males at older ages. The males castrated at 22d and tested at 35d had significantly lower escape latency and traveled distance during training than the sham-castrated males trained at the same age. No differences were observed in mean values of escape latency and traveled distance at 45d even though they had comparable levels of testosterone. We conclude that adult-typical performance for male spatial memory emerges during mid-adolescence and that pre-pubertal castration appears to improve spatial learning during this time.

Alteration in genes expression patterns during in vitro differentiation of mouse spermatogonial cells into neuroepithelial-like cells.

Pluripotent stem cells derived from testis is a new, natural, and unlimited source for cell therapy in regenerative medicine and represent a possible alternative to replacing of all cells in the body. Here, we designed a simple co-culture system of spermatogonia cells with Sertoli cells for the generation of embryonic stem-like cells from mouse testis. The importance of our simple method will be clear when we compared it with other complex and time-consuming methods. Embryonic stem-like colonies with sharp border confirmed by real-time PCR, immunocytochemistry and flow cytometry assessments. Embryonic stem-like colonies were immunopositive for pluripotency markers. Transition of spermatogonia cells to embryonic stem-like cells was accompanied by extensive changes in gene expression. These changes included significant increase in pluripotency genes expression and significant decrease in germ cell-specific genes expression. Also, we proved the differentiation capacity of embryonic stem-like cells to neuroepithelial-like cells which were immunoreactive to Nestin and Neurofilament 68. Evaluation of genes expression during in vitro differentiation into neuroepithelial-like cells showed high-level expression of Nestin whether this gene approximately has no expression in undifferentiated embryonic stem-like cells. Also, expression of pluripotency genes has significantly decreased in neuroepithelial-like cells compared with embryonic stem-like cells. This study shows that embryonic stem-like cells derived from testis are capable to differentiate into neuroepithelial-like cells that may provide a cellular reservoir usable for neurodegenerative disorders.

A Simple Co-culture System for Generation of Embryonic Stem-Like Cells From Testis.

BACKGROUND: New research proposes the pluripotency of spermatogonial cells obtained from testis. These spermatogonia-derived stem cells are called embryonic stem-like cells that express embryonic stem cell markers and differentiate to the three germ layers. OBJECTIVES: The aim of the present study was to generate embryonic stem-like cells from neonatal mouse testis. MATERIALS AND METHODS: The Testis cells were collected from neonatal mouse. After decapsulation, testis was mechanically dissected and dissociated via a two-step mechanical and enzymatic digestion. The spermatogonia and sertoli cells were cultured together in Dulbecco's modified Eagle's medium (DMEM) supplemented with 15% FBS and LIF. Before one week, several small spermatogonia colonies were observed on top of the monolayer of sertoli cells. These colonies were passaged every four days. ES-Like cells colonies that resembled ES cell was appeared within 2-3 weeks (at passages 5). Real time PCR was performed to analyze the expression of a subset of pluripotency markers, as well as germ cell-specific genes. ES Like cells were confirmed with SSEA1, SOX2 and Oct4 immunofluorescence stainng as pluripotency markers. RESULTS: The Results showed that at fifth passages, the pluripotency genes; Nanog and c-myc have significant increase in ES-Like cells in compare with spermatogonia cells, whereas the spermatogonial markers; Stra8, mvh, and piwill2 became downregulated. In addition to these pluripotency genes, the ES cell marker SSEA-1, SOX2 and Oct4 were expressed in the ES-like cells, similar to ES cells. CONCLUSIONS: This researh indicates pluripotency evidence of ES-like cells derived from testis. ES-like cells shows some molecular characteristics with embryonic stem cells.