Threshold for maximal electroshock seizures (MEST) at three developmental stages in young mice.

Early brain development after birth is extremely dynamic, suggesting that potential functional changes occur during this period. In this study, the maximal electroshock seizure threshold (MEST) was used to explore the electrophysiological variation among three developmental stages in young mice (no more than 5 weeks old). The induced electroshock seizure (ES) behavior of early postnatal mice (1-2-weeks old) differed from that during weaning (3 weeks old) and early puberty (4-5-weeks old). Thus, we further explored their respective characteristic responses to the ES parameters. When the stimulation current (SC) was limited to 4.0 mA, only the 1-2-week-old mice were induced to exhibit ES behavior at voltages of 30 V and 40 V, indicating they were more sensitive to maximal electroshock seizure (MES) (response to lower voltage). Surprisingly, however, they showed substantially lower mortality than the older groups under higher voltage conditions (60, 100, 160, and 200 V), suggesting better tolerance to the SC. We also found that when the current limit decreased to 3.5 mA, the 4-5-week-olds mice exhibited stable ES behavior with low mortality, while for 3-week-olds mice, the SC limit required to be reduced to 1.5 mA. In conclusion, our findings showed that neural sensitivity to MES was significantly different in young mice before puberty. Thus, greater attention should be given to distinguishing the developmental period of mice, especially in electrophysiological examination.

Neurons Differentiated from Transplanted Stem Cells Respond Functionally to Acoustic Stimuli in the Awake Monkey Brain.

Here, we examine whether neurons differentiated from transplanted stem cells can integrate into the host neural network and function in awake animals, a goal of transplanted stem cell therapy in the brain. We have developed a technique in which a small "hole" is created in the inferior colliculus (IC) of rhesus monkeys, then stem cells are transplanted in situ to allow for investigation of their integration into the auditory neural network. We found that some transplanted cells differentiated into mature neurons and formed synaptic input/output connections with the host neurons. In addition, c-Fos expression increased significantly in the cells after acoustic stimulation, and multichannel recordings indicated IC specific tuning activities in response to auditory stimulation. These results suggest that the transplanted cells have the potential to functionally integrate into the host neural network.

Divergence of dim-light vision among bats (order: Chiroptera) as estimated by molecular and electrophysiological methods.

Dim-light vision is present in all bats, but is divergent among species. Old-World fruit bats (Pteropodidae) have fully developed eyes; the eyes of insectivorous bats are generally degraded, and these bats rely on well-developed echolocation. An exception is the Emballonuridae, which are capable of laryngeal echolocation but prefer to use vision for navigation and have normal eyes. In this study, integrated methods, comprising manganese-enhanced magnetic resonance imaging (MEMRI), f-VEP and RNA-seq, were utilized to verify the divergence. The results of MEMRI showed that Pteropodidae bats have a much larger superior colliculus (SC)/ inferior colliculus (IC) volume ratio (3:1) than insectivorous bats (1:7). Furthermore, the absolute visual thresholds (log cd/m(2)•s) of Pteropodidae (-6.30 and -6.37) and Emballonuridae (-3.71) bats were lower than those of other insectivorous bats (-1.90). Finally, genes related to the visual pathway showed signs of positive selection, convergent evolution, upregulation and similar gene expression patterns in Pteropodidae and Emballonuridae bats. Different results imply that Pteropodidae and Emballonuridae bats have more developed vision than the insectivorous bats and suggest that further research on bat behavior is warranted.

[Glaucoma model for stem cell transplantation research in New Zealand white rabbits].

Glaucoma is a typical irreversible blind neurodegenerative disease for which there is no effective treatment for halting visual deterioration. The recent development of neural stem cells studies sheds light on a potential resolution for this disease. As a result, an appropriate glaucoma modeling method for stem cell transplantation study is needed. In the present study, Dexamethasone was injected unilaterally into the conjunctiva of New Zealand rabbit at the dose of 2.5 mg (5 mg/mL), three times a week. After eight weeks, the eye ground photography showed that the optic nerve head of the treated eye was expanded, and the blood vessel was geniculate compared to the control eye, while the ocular media remained transparent. The hematoxylin-eosin (HE) stain of the retinal nerve fiber layer (RNFL) sections showed optic neuron death in the treated eye. The Heidelberg Retina Tomography (HRT) results showed optic disk morphological changes consistent with the pathophysiology of glaucoma in the treated eye, including a decrease in the rim area (1.10±0.88) mm(2) and mean RNFL thickness (0.44±0.31) mm, and an increase in the cup/disk ratio 0.17±0.13. Then neural stem cells were injected into the vitreous body of the treated eye. After five months, surviving transplanted cells were observed. These results suggest a simple and reproducible chronic glaucoma model, which is appropriate for neural stem cell transplant research, has been successfully developed.