c‐Jun expression after cerebral hyperstimulation differs between rats and marmosets

Protective Effect of Total Panax Notoginseng Saponins on Retinal Ganglion Cells of an Optic Nerve Crush Injury Rat Model

Irreversible loss of retinal ganglion cells (RGCs) is a common pathological feature of various optic nerve degenerative diseases such as glaucoma and ischemic optic neuropathy. Effective protection of RGCs is the key to successful treatment of these diseases. Total Panax notoginseng saponins (TPNS) are the main active component of Panax notoginseng, which has an inhibitory effect on the apoptosis pathway. This study is aimed at assessing the protective effect of TPNS on RGCs of the optic nerve crush (ONC) model of rats and exploring the underlying mechanisms. The intraperitoneal or intravitreal injection of TPNS was used based on the establishment of the rat ONC model. Fifteen days after the injury, the cell membrane fluorescent probe (Fluoro-Gold) was applied to retrograde RGCs through the superior colliculus and obtain the number of surviving RGCs. TUNEL assay was also used to detect the number and density of RGC apoptosis after the ONC model. The expression and distribution of Bcl-2/Bax, c-Jun/P-c-Jun, and P-JNK in the retina were demonstrated by Western blot analysis. After the intervention of TPNS, the rate of cell survival increased in different retinal regions (p < 0.05) and the number of apoptosis cells decreased. Regarding the expression of Bcl-2/Bax, c-Jun/P-c-Jun, and P-JNK-related apoptotic proteins, TPNS can reduce the level of apoptosis and play a role in protecting RGCs (p < 0.05). These findings indicate that topical administration of TPNS can inhibit cell apoptosis and promote RGC survival in the crushed optic nerve.

Marmosets have a greater diversity of c-Fos response after hyperstimulation in distinct cortical regions as compared to rats

Previous evidence indicated a potential mechanism that might support the fact that primates exhibit greater neural integration capacity as a result of the activation of different structures of the central nervous system, as compared to rodents. The current study aimed to provide further evidence to confirm previous findings by analyzing the patterns of c-Fos expression in more neocortical structures of rats and marmosets using a more robust quantitative technique and evaluating a larger number of brain areas. Nineteen Wistar rats and 21 marmosets (Callithrix jacchus) were distributed among control groups (animals without injections) and animals injected with pentylenetetrazol (PTZ) and euthanized at different time points after stimulus. Immunohistochemical detection of c-Fos was quantified using unbiased and efficient stereological cell counting in eight neocortical regions. Marmosets had a c-Fos expression that was notably more widely expressed (5× more cells) and longer lasting (up to 3 hr) than rats. c-Fos expression in rats presented similar patterns of expression according to the function of the brain cortical structures (associative, sensorial, and motor functions), which was not observed for marmosets (in which no clear pattern could be drawn, and a more diverse profile emerged). Our results provide evidence that the marmoset brain has a greater neuronal activation after intense stimulation by means of PTZ and a more complex pattern of brain activation. We speculate that these functional differences may contribute for the understanding of the different neuronal processing capacities of the neocortex in these mammals' orders.