Temporal lobe epilepsy is often presented by medically intractable recurrent seizures due to dysfunction of temporal lobe structures, mostly the temporomesial structures. The role of transient receptor potential vaniloid 1 (TRPV1) activity on synaptic plasticity of the epileptic brain tissues was investigated. We studied hippocampal TRPV1 protein content and distribution in the hippocampus of epileptic rats. Furthermore, the effects of pharmacologic modulation of TRPV1 receptors on field excitatory postsynaptic potentials have been analyzed after induction of long term potentiation (LTP) in the hippocampal CA1 and CA3 areas after 1 day (acute phase) and 3 months (chronic phase) of pilocarpine-induced status epilepticus (SE). A higher expression of TRPV1 protein in the hippocampus as well as a higher distribution of this channel in CA1 and CA3 areas in both acute and chronic phases of pilocarpine-induced SE was observed. Activation of TRPV1 using capsaicin (1 µM) enhanced LTP induction in CA1 region in non-epileptic rats. Inhibition of TRPV1 by capsazepine (10 µM) did not affect LTP induction in non-epileptic rats. In acute phase of SE, activation of TRPV1 enhanced LTP in both CA1 and CA3 areas but TRPV1 inhibition did not affect LTP. In chronic phase of SE, application of TRPV1 antagonist enhanced LTP induction in CA1 and CA3 regions but TRPV1 activation had no effect on LTP. These findings indicate that a higher expression of TRPV1 in epileptic conditions is accompanied by a functional impact on the synaptic plasticity in the hippocampus. This suggests TRPV1 as a potential target in treatment of seizure attacks.
The critical role of Notch signaling has been shown in the pathogenesis of some neurological disorders including schizophrenia, epilepsy and Alzheimer’s disease. This study was aimed to evaluate the role of Notch 1 receptor in epileptogenesis as well as seizure characteristics. The animals were divided into three groups of sham, early stage and end stage. In sham group: Normal saline was injected intraperitoneally (ip) in the same as protocol of pentylenetetrazol (PTZ) injection. PTZ was injected (ip) every 48 hr over a period of 1 week in the group of early stage and over a period of 4 weeks in the end stage. The gene expression as well as distribution of Notch 1 receptor was assessed in the parietal cortex and hippocampus. In addition, the effect of agonist or antagonist of Notch 1 receptor was assessed on the epileptic discharges induced by PTZ injection. The gene expression of Notch 1 decreased in the hippocampus significantly in the end‐stage group compared with sham, and early groups. Furthermore, distribution of Notch 1 receptor increased in the somatosensory cortex and decreased in the CA1 hippocampal area in the end‐stage group. Intraventricular microinjection of Notch 1 agonist significantly increased the amplitude as well as frequency of spikes and decreased the latency of first epileptic discharges. Our findings illustrate the critical role of Notch signalling as a potential pathway in the epileptogenesis during development of chronic seizures.
Sex-dependent changes of behavioral responses in humans and animals has been widely investigated. There are also controversial reports regarding the role of sex hormones in memory and learning. The present study carried out to compare spatial learning of male, female and ovariectomized (OVX) rats in Morris water maze. Materials and Methods: Twenty four rats were divided into 3 groups: 1) male, 2) female, 3) OVX. The animals were ovariectomized under ketamine anesthesia (150 mg/kg, I.P.). The same procedure as OVX rats was performed on the female and male rats except the wound was closed without removing the ovaries.8 weeks later, the animals of all groups were tested in Morris Water Maze. The escape latency, traveled path lengh and swimming speed to reach the platform were compared between groups. Results: Time latency in both OVX and male groups was significantly higher than female group. However, path length in OVX group was higher than female group, there was no significant difference in path length between male and female or between male and OVX groups. The swimming speed in male group was lower than female group. Conclusion: It might be concluded that endogenous estrogen has an important role in sex dependent differences of spatial learning.
and memory in ovariectomized (OVX) rats. Materials & Methods Forthy-eight female Wistar rats were grouped as: 1) Sham, 2) OVX, 3) Sham-LA-A, 4) OVX-LA-A, 5) Sham-LA-C, 6) OVX-LA-C. The animals of sh-were compared between groups. Results Results showed that the escape latency and traveled path in Conclusion This indicates that L-Arg has a role in Morris water maze tasks disturbances in OVX rats.
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