Evidence of functional mossy fiber sprouting in hippocampal formation of kainic acid-treated rats.
نویسندگان
چکیده
In the rat hippocampal formation, degeneration of CA4-derived afferent fibers provokes the growth of mossy fiber collaterals into the fascia dentata. These aberrant fibers subsequently form granule cell-granule cell synapses. The hippocampal slice preparation was employed to determine whether these recurrent connections are electrophysiologically functional. Hippocampal slices were prepared 12 to 21 days after the bilateral destruction of CA4 neurons with either intracerebroventricular or intravenous kainic acid (KA). In slices from control rats, antidromic stimulation of the mossy fibers elicited a single population spike in the granular layer of the fascia dentata. In contrast, when slices from some KA-treated rats were similarly tested, antidromic stimulation elicited multiple population spikes. This effect was not reproduced by blocking inhibitory transmission with bicuculline methiodide. Slices from other KA-treated rats fired a single population spike, but an antidromic conditioning volley increased the amplitude of a subsequent antidromic population spike by 5 to 15%. In slices from control rats, on the other hand, an antidromic conditioning volley always either decreased or failed to alter the amplitude of an antidromic test response. Superfusion with Ca2+-free medium containing 3.8 mM Mg2+ reversibly abolished all effects of KA administration. Abnormal responses to antidromic stimulation correlated with the loss of CA4 neurons and the growth of supragranular mossy fiber collaterals in the same animals. These results suggest that supragranular mossy fiber collateral sprouts form a functional recurrent excitatory circuit. These aberrant connections may further compromise hippocampal function already disrupted by neuronal degeneration, such as by facilitating seizure activity.
منابع مشابه
Electroacupuncture at ST36-ST37 and at Ear Ameliorates Hippocampal Mossy Fiber Sprouting in Kainic Acid-Induced Epileptic Seizure Rats
Our previous study showed that mossy fiber sprouting can occur in the hippocampus region in rats 6 wk after kainic acid-induced epileptic seizure, and this mossy fiber sprouting can facilitate epileptogenesis. Transcutaneous auricular vagal nerve stimulation (VNS), which is similar to cervical VNS, can reduce the occurrence of epileptic seizure in intractable epilepsy patients. Greater parasymp...
متن کاملاثر عصاره الکلی سیاه‌دانه بر هیپوکمپ در موش صحرایی با صرع لب گیجگاهی
Background and Objective: Pathologically, temporal lobe epilepsy is hallmarked with neuronal degeneration in some areas of hippocampus and mossy fiber sprouting in dentate area. Considering some evidences on neuroprotective and antioxidant activity Nigella sativa (NS), this study was undertaken to evaluate the preventive effect of NS on structural changes in hippocampus of kainate-epileptic rat...
متن کاملContributions of mossy fiber and CA1 pyramidal cell sprouting to dentate granule cell hyperexcitability in kainic acid-treated hippocampal slice cultures.
Axonal sprouting like that of the mossy fibers is commonly associated with temporal lobe epilepsy, but its significance remains uncertain. To investigate the functional consequences of sprouting of mossy fibers and alternative pathways, kainic acid (KA) was used to induce robust mossy fiber sprouting in hippocampal slice cultures. Physiological comparisons documented many similarities in granul...
متن کاملRelations between brain pathology and temporal lobe epilepsy.
Temporal lobe epilepsy, the most common type of epilepsy in adult humans, is characterized clinically by the progressive development of spontaneous recurrent seizures of temporal lobe origin and pathologically by hippocampal neuronal loss and mossy fiber sprouting. In this study, we sought to test the prominent hypothesis that neuronal loss and mossy fiber sprouting play a critical role in the ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of neuroscience : the official journal of the Society for Neuroscience
دوره 5 4 شماره
صفحات -
تاریخ انتشار 1985