Experiment-time affects the cognitive behavior in aged Sprague-Dawley rats / 生理学报

In order to investigate if the experiment-time affects cognitive performance in aged rats in different learning and memory behavioral tests, the aged Sprague-Dawley (SD) rats were divided into two groups randomly and subjected to open field test, Morris water maze test and social discrimination test. The experiment of one group was conducted in 8:00 - 11:00 AM (AM group), and the other group in 15:00 - 18:00 PM (PM group). PM group exhibited higher locomotor activity than AM group in the open field test. Compared with AM group rats, PM group rats had significantly shorter swimming distance and escape latency to find the platform in Morris water maze training session, but no significant difference in the swimming velocity was observed between the two groups. And in probe-test, PM group spent more time in target quadrant than AM group. These results revealed that PM group showed better spatial learning and memory abilities than AM group. However, there was no significant difference between the two groups in social investigation index in social discrimination test. These results show that experiment-time may affect cognitive performance in Morris water maze but not in social discrimination task in aged rats. And the results indicate that experiment-time affects cognitive performance of aged rats selectively in different learning and memory behavioral tasks.

Inhibitory effect of anterior cingulate cortex on spontaneous activity of thalamic ventrobasal nucleus neurons / 生理学报

The purpose of this study was to investigate the influence of electrical stimulation of anterior cingulate cortex (ACC) on spontaneous activity of neurons in thalamic ventrobasal nucleus (VB). Experiments were performed on 12 male Sprague-Dawley rats weighing 250-310 g (4-5 months old). According to Paxinos and Watson's coordinate atlas of the rat, the frontal and parietal cortical areas were exposed by craniotomy, the recording electrodes were then inserted into the VB (P 2.4-4.1 mm, R 2.0-3.5 mm, H 5.2-6.8 mm) and the stimulating electrodes into the ACC (A 1.1-3.0 mm, R 0.0-1.0 mm, H 1.5-2.4 mm). Single-unit activities were recorded extracellularly in the VB by glass micropipettes (impedance 3-8 MOmega) filled with 0.5 mol/L sodium acetate solution containing saturated Fast Green. To study the effects of ACC activation on the spontaneous activities of VB cells, single electrical pulse (0.2 ms duration) was delivered to the ACC by a concentric bipolar stainless steel electrode (0.32 mm outer diameter). An effective ACC stimulation was determined for each VB neuron by gradually increasing the current intensity from 0.1 mA until either a significant change in the spontaneous activity of the VB neuron was observed, or the current intensity reached 0.4 mA. The results showed that ACC stimulation significantly suppressed the spontaneous activities in 12 out of 53 VB neurons (22.6%). (1) After the stimulation was delivered to ACC, the spontaneous activities of different VB neurons were totally suppressed for different time span. (2) There was obvious dose-effect relevance between ACC stimulation intensity and their inhibitory effect. The duration of complete inhibition was prolonged with the increases in the intensity and number of stimulation impulses in ACC. (3) The stimulation in the ACC depressed the spontaneous activities of VB neurons in different forms and this inhibition exhibited an accumulative effect. All these results indicate that the stimulation of ACC exerts an inhibitory influence on the spontaneous activities of VB neurons.

Effects of forepaw sensorimotor deprivation in early life on spatial learning and memory in rats / 上海第二医科大学学报

Objective To explore the effects of forepaw sensorimotor deprivation in early life on hippocampus-dependent spatial reference learning and memory in rats. Methods Newborn SD rats were randomly assigned to experiment group (deprivation of forepaw sensorimotor function, n=53) and control group(n=55). Rats of postnatal day 13 (PN13) in experiment group were seleeted, and models of forepaw sensorimotor deprivation were established by microsurgical technique. Open field tests and Morris water maze tests were performed during the time periods of PN25(PN21-31), PN35 (PN31-39), PN45(PN41-50) and PN60(PN56-64) to evaluate the locomotor activity and spatial reference learning and memory, respectively. Results In open field tests, there was no significant difference in parameters of locomotor activity and exploratory behavior between the two groups (P>0.05). In Morris water maze tests, eontrol group performed significantly better than experiment group during training sessions and probe tests on PN25 and PN35 (P<0.05). While on PN45, although there was no significant difference between the two groups during training sessions, control group performed significantly better than experiment group during probe tests (P<0.05). Conclusion The deprivation of forepaw sensorimotor in early life has no signifieant effect on the locomotor activity and exploratory behavior of rats, but can impair the spatial reference learning and memory.

An optimized recording method to characterize biophysical and pharmacological properties of acid-sensing ion channel / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To re-confirm and characterize the biophysical and pharmacological properties of endogenously expressed human acid-sensing ion channel 1a (hASIC1a) current in HEK293 cells with a modified perfusion methods.</p><p><b>METHODS</b>With cell floating method, which is separating the cultured cell from coverslip and putting the cell in front of perfusion tubing, whole cell patch clamp technique was used to record hASIC1a currents evoked by low pH external solution.</p><p><b>RESULTS</b>Using cell floating method, the amplitude of hASIC1a currents activated by pH 5.0 in HEK293 cells is twice as large as that by the conventional method where the cells remain attached to coverslip. The time to reach peak at two different recording conditions is (21+/-5) ms and (270+/-25) ms, respectively. Inactivation time constants are (496+/-23) ms and (2284+/-120) ms, respectively. The cell floating method significantly increases the amiloride potency of block on hASIC1a [IC50 is (3.4+/-1.1) micromol/L and (2.4+/- 0.9) micromol/L, respectively]. Both recording methods have similar pH activation EC50 (6.6+/-0.6, 6.6+/-0.7, respectively).</p><p><b>CONCLUSION</b>ASICs channel activation requires fast exchange of extracellular solution with the different pH values. With cell floating method, the presence of hASIC1a current was re-confirmed and the biophysical and pharmacological properties of hASIC1a channel in HEK293 cells were precisely characterized. This method could be used to study all ASICs and other ligand-gated channels that require fast extracellular solution exchange.</p>

A novel derivative of xanomeline improved memory function in aged mice / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To characterize the function of a new xanomeline-derived M1 agonist, 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1,2,5-thiadiazol-4-yl]-1,2,5,6- tetrahydro-1-methylpyridine Oxalate (EUK1001), the acute toxicity and the effects on synaptic plasticity and cognition of EUK1001 were evaluated.</p><p><b>METHODS</b>To examine the median lethal dose (LD50) of EUK1001, a wide dose range of EUK1001 was administered by p.o. and i.p. in aged mice. Furthermore, novel object recognition task and in vitro electrophysiological technique were utilized to investigate the effects of EUK1001 on recognition memory and hippocampal synaptic plasticity in aged mice.</p><p><b>RESULTS</b>EUK1001 exhibited lower toxicity than xanomeline, and improved the performance of aged mice in the novel object recognition test. In addition, bath application of 1 micromol/L EUK1001 directly induced long-term potentiation in the hippocampus slices.</p><p><b>CONCLUSION</b>We conclude that EUK1001 can improve the age-related cognitive deficits.</p>

Properties of tactile responses of neurons in rat thalamic ventroposterolateral nucleus / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To determine whether the convergences of tactile information also occur at thalamic ventroposterolateral nucleus in rats, we investigated the properties of tactile responses of the thalamic ventroposterolateral nucleus in rats.</p><p><b>METHODS</b>Unit responses were recorded extracellularly from thalamic ventroposterolateral nucleus in anesthetized rats.</p><p><b>RESULTS</b>Among 156 neurons examined, 140 neurons (89.7%) had the single, continual and small receptive fields, and 16 neurons (10.3%) had two discrete receptive fields. Some neurons?exhibited different responses to the same intensity stimulation which delivered to different points in their receptive fields. In addition, 4.5% neurons (n = 7) responded only to locomotive stimulation but?not to a punctiform tactile stimulation.</p><p><b>CONCLUSION</b>The majority of neurons in ventroposterolateral nucleus of rats have the spatial, temporal and submodal characteristics of cutaneous receptors, while the minority of neurons exhibit the responses of interaction of different peripheral receptors. Therefore, it is concluded that there are convergences of tactile information at the ventroposterolateral nucleus of rats.</p>