RESUMO
Currently, commercial devices for electrical neural stimulations can only provide fixed stimulation paradigms with preset constant parameters, while the development of new stimulation paradigms with time-varying parameters has emerged as one of the important research directions for expanding clinical applications. To facilitate the performance of electrical stimulation paradigms with time-varying parameters in animal experiments, the present study developed a well-integrated stimulation system to output various pulse sequences by designing a LabVIEW software to control a general data acquisition card and an electrical stimulus isolator. The system was able to generate pulse sequences with inter-pulse-intervals (IPI) randomly varying in real time with specific distributions such as uniform distribution, normal distribution, gamma distribution and Poisson distribution. It was also able to generate pulse sequences with arbitrary time-varying IPIs. In addition, the pulse parameters, including pulse amplitude, pulse width, interphase delay of biphasic pulse and duration of pulse sequence, were adjustable. The results of performance tests of the stimulation system showed that the errors of the parameters of pulse sequences output by the system were all less than 1%. By utilizing the stimulation system, pulse sequences with IPI randomly varying in the range of 5~10 ms were generated and applied in rat hippocampal regions for animal experiments. The experimental results showed that, even with a same mean pulse frequency of ~130 Hz, for neuronal populations, the excitatory effect of stimulations with randomly varying IPIs was significantly greater than the effect of stimulations with fixed IPIs. In conclusion, the stimulation system designed here may provide a useful tool for the researches and the development of new paradigms of neural electrical stimulations.
Assuntos
Animais , Ratos , Estimulação Elétrica , NeurôniosRESUMO
Objective To investigate the effect of maternal separation (MS) on cognitive function in adult male rats through the expression of neuronal nitric oxide synthase (nNOS) in hippocampus, and to reveal the roles of early life stress (ELS) on neural development in rats. Methods Healthy SD pregnant rats (n=12) were randomly divided into maternal separation group (MS group) and control group (NMS group) (n=6 for each group). The newborn rats in the MS group were separated from the mother rats for 3 h every day from postnatal day 3 to 22 whereas no intervention was taken in the NMS group. At the age of 10 weeks, Morris water maze was used to test the learning and memory abilities of two groups of offspring male rats. Neuron immunofluorescence staining was used to examine the number and distribution of neurons in dentate gyrus (DG) of two groups of offspring male rats. Western Blot method was used to detect nNOS, eNOS, Bax/BCL2, Caspase-3 and P53 levels in the hippocampus of the two groups. Ki67/DCX immunofluorescence staining were used to examine the proliferation and differentiation of neurons in the DG area of the hippocampus. TUNEL staining was used to detect the neuronal degeneration and death in the DG area of the hippocampus. Results Behavioral tests showed that the escape latency of male rats in MS group was prolonged, the target quadrant residence time and the number of platform crossing decreased (P<0.05) compared with NMS group. Compared with NMS group, the number of normal and degenerated neurons in hippocampal DG area of MS group had no significant change (P＞0.05). However, the expression of nNOS and eNOS in hippocampus was decreased (P<0.05) and the expression of Bax/BCL2 was increased (P<0.05), but the expression of caspase-3 and P53 remained unchanged (P＞0.05). In addition, Neuronal proliferation and differentiation were decreased and apoptosis was increased in MS group (P<0.05). Conclusion Repeated MS reduces the expression levels of nNOS in the hippocampus, affects the neuronal function in the DG area, and has a long-term influence on the neurodevelopment, which results in cognitive deficits related to learning and memory abilities in adult rats.
RESUMO
Nitric oxide (NO) modulates the activities of various channels and receptors to participate in the regulation of neuronal intracellular Ca2+ levels. Ca2+ binding protein (CaBP) expression may also be altered by NO. Accordingly, we examined expression changes in calbindin-D28k, calretinin, and parvalbumin in the cerebral cortex and hippocampal region of neuronal NO synthase knockout(-/-) (nNOS-/-) mice using immunohistochemistry. For the first time, we demonstrate that the expression of CaBPs is specifically altered in the cerebral cortex and hippocampal region of nNOS-/- mice and that their expression changed according to neuronal type. As changes in CaBP expression can influence temporal and spatial intracellular Ca2+ levels, it appears that NO may be involved in various functions, such as modulating neuronal Ca2+ homeostasis, regulating synaptic transmission, and neuroprotection, by influencing the expression of CaBPs. Therefore, these results suggest another mechanism by which NO participates in the regulation of neuronal Ca2+ homeostasis. However, the exact mechanisms of this regulation and its functional significance require further investigation.