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Kindled amygdaloid seizures and protein kinase C activity in rat limbic structures
Session IO:,Experimental EEG of the 10 animals given IO nmol, in 5 of the 6 animals given 50 nmol, and in 5 of the 7 animals given 100 nmol. kindled Stage 5 seizures regressed to Stage
1 or 2 seizure. In all the animals given muscimoi, afterdischarge was readily generated at the GST with a slight reduction in its duration. The findings indicate that bilateral intra-striatal muscimol suppresses the kindled seizure without affecting the excitability of the kindled amygdala. Since GABA appears to serve as a neurotransmitter in the striatal interneurons, the effect of intra-striatal muscimol was probably due to GABA-mediated inhibition of the striatai output systems.
~~~~b~t~~~Effect of S-OH-DPAT Microinjections on Partial and Generalized Kindled Seizures from the M. Nakamura. Y. Wada, H. Hasegawa, N. Yamaguchi. KanazawaUnivers&
Kanazawa Despite numerous studies on functional correlates for different serotonin (5HT) receptors, very little is known about the role of the 5-HT receptor subtypes in epilepsy. We previously reported that the intravenous injection of a 5-Hit~ receptor agonist, 8-hydroxy-2_(di+propylamino)tetralin @OHDPA?), can suppress seizures kindled from the feline hippocampus (HIP) (Neurosci Let?,, 141:21-24, 1992). To further clarify the role of 5.HTIA receptors in epilepsy, this study examined the effects of intra-HIP injections of 8-OH-DPAT(1 and i0 nmol) on partial and generalized HIP seizures. Microinjections of 8-OH-DPAT at IO nmol. but not 1 nmol, produced a significant elevation in the afterdischarge (AD) threshold of partial HIP seizures, as compared with vehicle microinjected into the same region. This suppressive action of 8OH-DPAT was accompanied by a significant reduction in the duration of focal ADS. In addition, intra-HIP injections of 8-OH-DPAT at 10 nmol completely abolished fully kindled seizures in all cats, and significantly raised the seizure threshold for eliciting generalized seizures. With increasing stimulus intensity, however, a generalized seizure was reactivated in ail cats without a significant change in the AD duration. These data indicate that focally applied 8OH-DPAT possesses a potent anticonvulsant action against seizure activity elicited by electrical stimulation to the HIP and suggest the inhibitory role of ~-HT~,J receptors in the generation of HIP seizures.
1 1 O-08
/ Effect of Intravenous Liposame-Entrapped ~i~be~~~hydant~in in Amygdaloid-Kindled
M. Oka. A. Kurokouchi. Japan
N. Mori. Fukushima Medical
Rats
College, Fukushima,
Liposomes are microscopic vesicles composed of one or more lipid membranes surrounding discrete aqueous compartments. Liposomes can enhance the effectiveness of entrapped drugs, and this appears to be due, at least in part, to an action of rhe liposomes as a sustained release reservoir. In this study, the anticonvulsant effect of intravenously given diphenylhydantoin (DPH) and liposome-entrapped DPH was examined in amygdaloid-kindled rats. We also measured the serum concentration of DPH after the intravenous DPH or liposome-entrapped DPH administration. Male Wistar rats were kindled at the left amygdala, and the generalized seizure triggering threshold (GST) was determined. The kindled animals received intravenous DPH (n = 6). liposome-entrapped DPH (n = 9). or liposomes alone (n = 7). each at 20 mgikg (1 ml/kg). Ninety min after the administration, the kindled amygdala was stimulated at the GST In another group of animals, DPH (n = 6) and liposome-entrapped DPH (n = 5) were given intravenously. Ninety min later, the serum concentration of DPH was determined. The DPH and the liposomes alone were totally ineffective. In the liposome-entrapped DPH group, however, kindled stage 5 seizure decreased to a mean stage of 2.8. Thus, the Iiposome-entrapped DPH suppressed the kindled seizure significantly compared to DPH or liposomes (p < 0.05). There was no signrficant difference in the serum DPH between DPH and liposome-entrapped DPIH groups: 22.5 fig/ml in the DPH group and 25.3 *g/ml in the liposome-entrapped DPH group. These findings suggest that entrapping DP% into liposomes increases its anticonvulsant effect without influencing its serum ievel.
1 1 O-09 / Kindled Amygdaloid
Seizures and ~~Q~~~~
Activity in Rat Limbic St~~~t~r~~ K. Osonoe, M. Osonoe, S. Ogata. Y. lwata, N !Mori. Fukushima Medi;Jal College, Fukushima, Japan In the present study. protein kinase C (PKC) activity was measured in the rat hippocampus (HIPP) and amygdala (AM) during kindled AM seizure, and 30 min. 3, 24 and 48 hr, and 2 weeks after the last kindled seizure. The results were compared with those obtained in sham-operated controls. During seizures, the membrane-bound PKC activity in the HIPP was significant!y increased without overt change in the cytosolic PKC activity, In the AM, no change was found in the PKC activity of either fraction. At 30 min. the PKC activity of both fractions was markedly increased in all regions. At 3 hr. however, the membrane-bound PKC activity was significantly decreased in both regions. In the HIPS: the cytosolic PKC activity was also decreased. At 24 hr. the membrane-bound PKC activity was significantly decreased in both regions examined. whereas no change was found in the cytosolic PKC activity. Forty-eight hr and 2 weeks after the last kindled seizure, nether the membrane-bound rnor cytosolic PKC activity showed any alteration in either region. These findings suggest that kindled amygdalord seizures cause an immediate and transient increase in PKC activity in limbic structures, followed by suppression of the enzyme activity, and that PKC in the hippocampus responds to kindled seizures more readily and preferentially than does that in the amygdala. Examination of the direct effect of kindled seizures on PKC activity may be important for understanding the relationship between kindled phenomenon and the PKC in limbic structures.
1 O-l 0
Suppression of Kindled ~e~~~~~ Intra-Striatal lnjectiori af 3-(2-Carboxypiperazine-~-yl)Pra Acid (CPP) in A~ygdal0id~~imd
M. Osonoe, S. Hoshino. N. Mon. Fukushima Medicai’Coliege, Japan
Fukushima,
The effect of intra-striatal injection of 3-(2.carboxypiperazine-4.ynpropyl1-phosphonic acid (CPP), a competitive N-methyl-D-aspartate (NMDA) antagonist. was examined in amygdaloid (AM)-kindled rats. Male Wistar rats were kindled at the left AM, and the generalized seizure triggering threshold (GST) was determined. The AM-kindled animals received bilateral intra-striatal injections of vehicle (saline) (n = 6). 2.5 nmol CPP (n = 7), and 10 nmol CPP (n = 7). each at a volume of 0.5 /LI. One hour after the microinjection, the kindled AM was stimulated at the GST. Intra-striate1 injection of saline caused no apparent behavioral change, and did not alter the effect of AM stimulation. Intra-striatal injection of 2.5 nmol CPP caused no behavioral change, and that of 10 nmol CPP caused behavioral change characterized by uncoordinated movement of limbs. When the kindled AM was stimulated a? the GST after the injection, kindled seizures were markedly suppressed in a dose-dependent manner. In all the animals given intra-striatal CPP AD was readily evoked at the GST with a slight reduction in its duration, These findings suggest that intra-striatal injection of CPP suppresses kindled AM seizures without affecting AM excitability, and that NMDA receptors in the striatum participate in the mechanism underlying the expression and generalization of kindled AM seizures.
1 O-l 1
Mossy Fiber Synaptic Ra~r~~~i~ Epilepticus in Rats
H. Saito, K. Tsunoda, S. ltagaki, H. Kittaka. N. Mori. Fukush;ma Medicai College, Fukushima, Japan Granule cell axons or mossy fibers innervate neurons in the hilus and CA3iCA4 subfield of the hippocampus. Recent studies revealed that mossy fiber sprouting occurred following limbic motor seizures induced by kainic acid or kindling, and also in the epileptic human temporal lobe. However, there have been no reports on the morphological alteration in the neuronai dendrites associated with epileptic seizures, In this study, status epilepticus was induced by microinjection of dibutyryl-CAMP into the amygdaia in rats. Two weeks later, distribution and alteration of mossy fiber terminals and microtubule-associated protein 2 (MAP2). which is one of the cytoskeleta! proteins and abundant in neuronal dendrites, were examined in the hippocampus. Mossy fiber terminals were stained by Timm histochemistry. and MAP2 was stained by immunohistological techniques.
1 or 2 seizure. In all the animals given muscimoi, afterdischarge was readily generated at the GST with a slight reduction in its duration. The findings indicate that bilateral intra-striatal muscimol suppresses the kindled seizure without affecting the excitability of the kindled amygdala. Since GABA appears to serve as a neurotransmitter in the striatal interneurons, the effect of intra-striatal muscimol was probably due to GABA-mediated inhibition of the striatai output systems.
~~~~b~t~~~Effect of S-OH-DPAT Microinjections on Partial and Generalized Kindled Seizures from the M. Nakamura. Y. Wada, H. Hasegawa, N. Yamaguchi. KanazawaUnivers&
Kanazawa Despite numerous studies on functional correlates for different serotonin (5HT) receptors, very little is known about the role of the 5-HT receptor subtypes in epilepsy. We previously reported that the intravenous injection of a 5-Hit~ receptor agonist, 8-hydroxy-2_(di+propylamino)tetralin @OHDPA?), can suppress seizures kindled from the feline hippocampus (HIP) (Neurosci Let?,, 141:21-24, 1992). To further clarify the role of 5.HTIA receptors in epilepsy, this study examined the effects of intra-HIP injections of 8-OH-DPAT(1 and i0 nmol) on partial and generalized HIP seizures. Microinjections of 8-OH-DPAT at IO nmol. but not 1 nmol, produced a significant elevation in the afterdischarge (AD) threshold of partial HIP seizures, as compared with vehicle microinjected into the same region. This suppressive action of 8OH-DPAT was accompanied by a significant reduction in the duration of focal ADS. In addition, intra-HIP injections of 8-OH-DPAT at 10 nmol completely abolished fully kindled seizures in all cats, and significantly raised the seizure threshold for eliciting generalized seizures. With increasing stimulus intensity, however, a generalized seizure was reactivated in ail cats without a significant change in the AD duration. These data indicate that focally applied 8OH-DPAT possesses a potent anticonvulsant action against seizure activity elicited by electrical stimulation to the HIP and suggest the inhibitory role of ~-HT~,J receptors in the generation of HIP seizures.
1 1 O-08
/ Effect of Intravenous Liposame-Entrapped ~i~be~~~hydant~in in Amygdaloid-Kindled
M. Oka. A. Kurokouchi. Japan
N. Mori. Fukushima Medical
Rats
College, Fukushima,
Liposomes are microscopic vesicles composed of one or more lipid membranes surrounding discrete aqueous compartments. Liposomes can enhance the effectiveness of entrapped drugs, and this appears to be due, at least in part, to an action of rhe liposomes as a sustained release reservoir. In this study, the anticonvulsant effect of intravenously given diphenylhydantoin (DPH) and liposome-entrapped DPH was examined in amygdaloid-kindled rats. We also measured the serum concentration of DPH after the intravenous DPH or liposome-entrapped DPH administration. Male Wistar rats were kindled at the left amygdala, and the generalized seizure triggering threshold (GST) was determined. The kindled animals received intravenous DPH (n = 6). liposome-entrapped DPH (n = 9). or liposomes alone (n = 7). each at 20 mgikg (1 ml/kg). Ninety min after the administration, the kindled amygdala was stimulated at the GST In another group of animals, DPH (n = 6) and liposome-entrapped DPH (n = 5) were given intravenously. Ninety min later, the serum concentration of DPH was determined. The DPH and the liposomes alone were totally ineffective. In the liposome-entrapped DPH group, however, kindled stage 5 seizure decreased to a mean stage of 2.8. Thus, the Iiposome-entrapped DPH suppressed the kindled seizure significantly compared to DPH or liposomes (p < 0.05). There was no signrficant difference in the serum DPH between DPH and liposome-entrapped DPIH groups: 22.5 fig/ml in the DPH group and 25.3 *g/ml in the liposome-entrapped DPH group. These findings suggest that entrapping DP% into liposomes increases its anticonvulsant effect without influencing its serum ievel.
1 1 O-09 / Kindled Amygdaloid
Seizures and ~~Q~~~~
Activity in Rat Limbic St~~~t~r~~ K. Osonoe, M. Osonoe, S. Ogata. Y. lwata, N !Mori. Fukushima Medi;Jal College, Fukushima, Japan In the present study. protein kinase C (PKC) activity was measured in the rat hippocampus (HIPP) and amygdala (AM) during kindled AM seizure, and 30 min. 3, 24 and 48 hr, and 2 weeks after the last kindled seizure. The results were compared with those obtained in sham-operated controls. During seizures, the membrane-bound PKC activity in the HIPP was significant!y increased without overt change in the cytosolic PKC activity, In the AM, no change was found in the PKC activity of either fraction. At 30 min. the PKC activity of both fractions was markedly increased in all regions. At 3 hr. however, the membrane-bound PKC activity was significantly decreased in both regions. In the HIPS: the cytosolic PKC activity was also decreased. At 24 hr. the membrane-bound PKC activity was significantly decreased in both regions examined. whereas no change was found in the cytosolic PKC activity. Forty-eight hr and 2 weeks after the last kindled seizure, nether the membrane-bound rnor cytosolic PKC activity showed any alteration in either region. These findings suggest that kindled amygdalord seizures cause an immediate and transient increase in PKC activity in limbic structures, followed by suppression of the enzyme activity, and that PKC in the hippocampus responds to kindled seizures more readily and preferentially than does that in the amygdala. Examination of the direct effect of kindled seizures on PKC activity may be important for understanding the relationship between kindled phenomenon and the PKC in limbic structures.
1 O-l 0
Suppression of Kindled ~e~~~~~ Intra-Striatal lnjectiori af 3-(2-Carboxypiperazine-~-yl)Pra Acid (CPP) in A~ygdal0id~~imd
M. Osonoe, S. Hoshino. N. Mon. Fukushima Medicai’Coliege, Japan
Fukushima,
The effect of intra-striatal injection of 3-(2.carboxypiperazine-4.ynpropyl1-phosphonic acid (CPP), a competitive N-methyl-D-aspartate (NMDA) antagonist. was examined in amygdaloid (AM)-kindled rats. Male Wistar rats were kindled at the left AM, and the generalized seizure triggering threshold (GST) was determined. The AM-kindled animals received bilateral intra-striatal injections of vehicle (saline) (n = 6). 2.5 nmol CPP (n = 7), and 10 nmol CPP (n = 7). each at a volume of 0.5 /LI. One hour after the microinjection, the kindled AM was stimulated at the GST. Intra-striate1 injection of saline caused no apparent behavioral change, and did not alter the effect of AM stimulation. Intra-striatal injection of 2.5 nmol CPP caused no behavioral change, and that of 10 nmol CPP caused behavioral change characterized by uncoordinated movement of limbs. When the kindled AM was stimulated a? the GST after the injection, kindled seizures were markedly suppressed in a dose-dependent manner. In all the animals given intra-striatal CPP AD was readily evoked at the GST with a slight reduction in its duration, These findings suggest that intra-striatal injection of CPP suppresses kindled AM seizures without affecting AM excitability, and that NMDA receptors in the striatum participate in the mechanism underlying the expression and generalization of kindled AM seizures.
1 O-l 1
Mossy Fiber Synaptic Ra~r~~~i~ Epilepticus in Rats
H. Saito, K. Tsunoda, S. ltagaki, H. Kittaka. N. Mori. Fukush;ma Medicai College, Fukushima, Japan Granule cell axons or mossy fibers innervate neurons in the hilus and CA3iCA4 subfield of the hippocampus. Recent studies revealed that mossy fiber sprouting occurred following limbic motor seizures induced by kainic acid or kindling, and also in the epileptic human temporal lobe. However, there have been no reports on the morphological alteration in the neuronai dendrites associated with epileptic seizures, In this study, status epilepticus was induced by microinjection of dibutyryl-CAMP into the amygdaia in rats. Two weeks later, distribution and alteration of mossy fiber terminals and microtubule-associated protein 2 (MAP2). which is one of the cytoskeleta! proteins and abundant in neuronal dendrites, were examined in the hippocampus. Mossy fiber terminals were stained by Timm histochemistry. and MAP2 was stained by immunohistological techniques.