ABSTRACT
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.
Subject(s)
Electric Stimulation , Gyrus Cinguli/physiology , Neurons/cytology , Thalamic Nuclei/cytology , Animals , Male , Rats , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: We conclude that EUK1001 can improve the age-related cognitive deficits.
Subject(s)
Brain/drug effects , Memory/drug effects , Muscarinic Agonists/administration & dosage , Muscarinic Agonists/adverse effects , Pyridines/administration & dosage , Pyridines/adverse effects , Thiadiazoles/administration & dosage , Thiadiazoles/adverse effects , Aging/drug effects , Animals , Dose-Response Relationship, Drug , Excitatory Postsynaptic Potentials/drug effects , Lethal Dose 50 , Long-Term Potentiation/drug effects , Mice , Pyridines/chemistry , Thiadiazoles/chemistryABSTRACT
OBJECTIVE: 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. METHODS: Unit responses were recorded extracellularly from thalamic ventroposterolateral nucleus in anesthetized rats. RESULTS: 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. CONCLUSION: 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.
