Leyla Aydin

Anticonvulsant efficacy of melatonin in an experimental model of hyperthermic febrile seizures

INTRODUCTION The anticonvulsant effects of melatonin (MT) have been demonstrated in several different experimental seizure models. Thus, the present study aimed to determine the anticonvulsant efficacy of MT, the optimum time for its administration prior to the induction of a seizure, and its effective dose in a rat model of hyperthermic febrile seizures (FSs). METHODS The present study included 72 male Sprague-Dawley rat pups divided into eight groups. The seizures were induced by keeping the rats in 45 °C water and the experiments were performed in two steps. In the first step, the control group was given a vehicle injection and the study groups were given a MT injection (150 mg/kg, intraperitoneal [i.p.]) at either 5, 10, or 15 min prior to the induction of the seizure to determine the anticonvulsant effects of MT and its optimum time of administration. In the second step, a vehicle injection and three different doses of MT (80, 100, and 150 mg/kg, i.p.) were administered 15 min prior to the induction of the seizure to determine the dose at which anticonvulsant effects could be achieved. The anticonvulsant effects were assessed based on the latency of the FSs. RESULTS In the first-step experiments, the FS latency of the control group was 143.4 ± 15.3s and the latencies of the groups given melatonin at either 5, 10, or 15 min prior to the seizure were 174.2 ± 28.9, 177.4 ± 21.0, and 193.7 ± 17.6s, respectively. Compared with the control group, the latencies for each of the study groups were significantly longer (p<0.001), with the longest latency observed in the group given melatonin 15 min before the seizure. In the second-step experiments, the FS latencies of the groups that were given 80, 100, and 150 mg/kg of MT 15 min before the seizure were 238.7 ± 4.0, 240.0 ± 0.0, and 193.7 ± 17.6s, respectively. These latencies were significantly longer than those of the control group (172.3 ± 30.3s, p<0.001). CONCLUSION The present study demonstrated that MT exerts anticonvulsant effects in a rat model of hyperthermic FSs and achieved its optimum efficacy at a dose of 80 mg/kg when administered 15 min prior to the induction of a seizure.

Adipose-derived Stem Cells Enhance Axonal Regeneration through Cross-facial Nerve Grafting in a Rat Model of Facial Paralysis

Background: Cross-face nerve grafting combined with functional muscle transplantation has become the standard in reconstructing an emotionally controlled smile in complete irreversible facial palsy. However, the efficacy of this procedure depends on the ability of regenerating axons to breach two nerve coaptations and reinnervate endplates in denervated muscle. The current study tested the hypothesis that adipose-derived stem cells would enhance axonal regeneration through a cross-facial nerve graft and thereby enhance recovery of the facial nerve function. Methods: Twelve rats underwent transection of the right facial nerve, and cross-facial nerve grafting using the sciatic nerve as an interpositional graft, with coaptations to the ipsilateral and contralateral buccal branches, was carried out. Rats were divided equally into two groups: a grafted but nontreated control group and a grafted and adipose-derived stem cell–treated group. Three months after surgery, biometric and electrophysiologic assessments of vibrissae movements were performed. Histologically, the spectra of fiber density, myelin sheath thickness, fiber diameter, and g ratio of the nerve were analyzed. Immunohistochemical staining was performed for the evaluation of acetylcholine in the neuromuscular junctions. Results: The data from the biometric and electrophysiologic analysis of vibrissae movements, immunohistochemical analysis, and histologic assessment of the nerve showed that adipose-derived stem cells significantly enhanced axonal regeneration through the graft. Conclusion: These observations suggest that adipose-derived stem cells could be a clinically translatable route toward new methods to enhance recovery after cross-facial nerve grafting.

Effect of melatonin on cytokine levels in a hyperthermia-induced febrile seizure model

Higher serum cytokine levels have been reported in children admitted with febrile seizures and in some experimental models. However, other studies have shown that cytokine levels are influenced by melatonin. In this study, we investigated serum cytokine levels in a hyperthermia-induced febrile rat seizure model and the effect of melatonin. A total of 28 male Sprague-Dawley rats were divided into four groups: the control (C) group, healthy melatonin (MT) group, and hyperthermia-induced febrile seizure groups with (HIFS-MT) and without (HIFS) administration of melatonin. Melatonin (80 mg/kg) was given intraperitoneally 15 min before the seizure. HIFS was induced by placing the rats in 45°C water. The rats were sacrificed under anesthesia after the seizure. Blood samples were drawn by transcardiac puncture to measure serum cytokine and melatonin levels. Serum interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor (TNF)-α levels were lower in the HIFS group than those in the C group (p = 0.005, p = 0.200, p = 0.011, and p = 0.016, respectively). All serum cytokine levels of rats in the MT and HIFS-MT groups were similar to those in the C group. This experimental rat model demonstrated that serum cytokine levels decrease with HIFS and that administering melatonin maintains serum cytokine levels. These results suggest that cytokines may play role in the anticonvulsive activity of melatonin in rats with febrile seizures.

Polyphasic Temporal Behavior of Finger-Tapping Performance: A Measure of Motor Skills and Fatigue

ABSTRACT Successive voluntary motor movement involves a number of physiological mechanisms and may reflect motor skill development and neuromuscular fatigue. In this study, the temporal behavior of finger tapping was investigated in relation to motor skills and fatigue by using a long-term computer-based test. The finger-tapping performances of 29 healthy male volunteers were analyzed using linear and nonlinear regression models established for inter-tapping interval. The results suggest that finger-tapping performance exhibits a polyphasic nature, and has several characteristic time points, which may be directly related to muscle dynamics and energy consumption. In conclusion, we believe that future studies evaluating the polyphasic nature of the maximal voluntary movement will lead to the definition of objective scales that can be used in the follow up of some neuromuscular diseases, as well as, the determination of motor skills, individual ability, and peripheral fatigue through the use of a low cost, easy-to-use computer-based finger-tapping test.