Primate neurons show different vulnerability to transient ischemia and response to cathepsin inhibition

Previously, we reported "calpain-induced leakage of lysosomal enzyme cathepsin" as a mechanism of ischemic neuronal death specific for primates. Cathepsin inhibitors such as CA-074 and E-64c were demonstrated to significantly inhibit hippocampal neuronal death. Pyramidal neurons of the hippocampus, Purkinje cells in the cerebellum, and neurons in the caudate nucleus, outer putamen and cortical III, V layers, are known to be vulnerable to ischemia. However, regional differences of the vulnerability and response to neuroprotectants, have not been studied in detail. Here, the monkey brains undergoing transient ischemia were studied to clarify such regional differences by the microscopic counting of surviving neurons. The dead neurons were characterized by eosinophilic coagulation necrosis without apoptotic bodies. The control postischemic brain without treatment showed surviving neurons in caudate nucleus (55.8%), outer putamen (44.4%), cortical III layer (37.8%), CA4 (35.3%), cortical V layer (34.1%), cerebellum (28.2%), CA3 (24.3%), CA2 (16.2%), and CA1 (2.0%). Only the CA1 showed an almost total neuronal loss. In contrast, a single postictal injection of CA-074 or E-64c led to significant inhibition of postischemic neuronal death in all brain regions studied. Overall, more surviving neurons were seen after E-64c treatment than with CA-074: cerebellum, 91.6% vs 85.6%; CA4, 88.6% vs 77.3%; caudate nucleus, 86.1% vs 89.8%; CA2, 83.6% vs 53.0%; outer putamen, 81.3% vs 87.7%; CA1, 80.1% vs 47.4%; CA3, 79.6% vs 60.3%; cortical layer III, 75.5% vs 67.7%; and cortical layer V, 75.0% vs 65.9%, for E-64c and CA-074, respectively. Cathepsin plays a critical role in ischemic neuronal death, and its inhibitors may protect neurons throughout the brain.     

Effects of estrogen on acetylcholine release in frontal cortex of female rats: involvement of serotonergic neuronal systems

The effects of estrogen on cortically projecting cholinergic neurons were investigated using in vivo microdialysis to measure cortical basal acetylcholine (ACh) levels and serotonin (5-HT)-stimulated ACh release in frontal cortex of freely moving Wistar female rats. Bilateral ovariectomy (OVX) or sham operations were performed under anesthesia. Immediately after surgery, each OVX animal was subcutaneously implanted with pellet containing 0.1/0.5 mg of 17beta-estradiol (E(2)) or a vehicle. Nineteen days later, a transverse microdialysis probe was stereotaxically implanted in the frontal cortex (AP: +2.7 mm, DV: -2.5 mm relative to bregma). Two days later (21 days after beginning of estrogen treatment), in vivo microdialysis experimentation was conducted. Serum E(2) levels of animals with 0.1 and 0.5 mg-pellets were equivalent to those levels during diestrous and proestrous, respectively. Although the replacement of different amounts of E(2) produced significant changes in body weight, it failed to affect basal ACh levels in the frontal cortex. Systemically administered serotonin releasing agent, fenfluramine, significantly increased cortical ACh release in all animal groups. The fenfluramine's ability to increase ACh release was potentiated by E(2) replacement with a 0.5 mg-pellet. E(2)-induced enhancement was also observed when the selective 5-HT(1A) agonist, 8-hydroxy-2-(di-n-propylamino) tetralin, but not the 5-HT(2A/2C) agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, was administered. Therefore, the effect of estrogen on 5-HT-stimulated ACh release might be exerted partly via 5-HT(1A) receptors, and not via 5-HT(2) receptors. These results suggest that the positive effects of estrogen on cognitive functions might be mediated through the ACh-5-HT interactions.     

Complex partial status epilepticus induced by a microinjection of kainic acid into unilateral amygdala in dogs and its brain damage

OBJECTIVE: In order to investigate kainic acid (KA)-induced amygdaloid seizure and seizure-induced brain damage in dogs, and to compare these findings with that in other species, a KA-induced seizure model in dogs was produced. MATERIAL AND METHODS: Normal beagle dogs were used. A Teflon cannula for KA injection was inserted into the left amygdala, and cortical or depth electrodes were positioned. One week after surgery, 1.5 microg of KA was microinjected into the left amygdala. EEGs and the behavior of the animals were monitored for 2 months after KA injection. In addition, neuron-specific enolase levels in the cerebrospinal fluid (CSF-NSE) were measured intermittently. At 2 months after the injection, histopathological studies were performed. RESULTS: KA-treated dogs showed limbic seizures that started from the left amygdala within 30 min after injection. The seizures developed into complex partial status epilepticus (CPSE), and started independently from the bilateral amygdala during the CPSE. The CPSE lasted for 1-3 days, and the animals showed no spontaneous seizures during the 2-month observation period. A significant increase in CSF-NSE was observed immediately after CPSE. Histopathologically, extensive necrosis, which formed large cavity lesions, was observed around the bilateral amygdala. SUMMARY: A microinjection of KA into unilateral amygdala in dogs induced CPSE. The seizures elicited independently from bilateral amygdala, and bilateral limbic structures suffered extensive injury. In addition, CSF-NSE was demonstrated as a useful marker of acute neuronal damage.     

Increased expression of mRNAs for microtubule disassembly molecules during nerve regeneration

The mRNA expression of the microtubule disassembly molecules (SCG10, stathmin, SCLIP and RB3) in response to nerve injury was examined using a rat hypoglossal nerve injury model. After nerve injury prominent increase in mRNA expression of SCG10, stathmin and RB3 was observed, while only slight increase in SCLIP mRNA was observed in injured motor neurons. The increase in SCG10 and RB3 mRNA expression was quicker than that of stathmin and SCLIP. All the elevated signals decreased gradually to control levels by 4 weeks after nerve injury.     

Endoscopic comparison of two cases: distal resection of reconstructed gastric tube

Recently, with the improvement of the prognosis of esophageal cancer, subsequent gastric cancer has increased. However, the standard surgical treatment for such patients has not been established as of yet. Since the patient's physical condition is relatively poor after Ivor-Lewis esophagectomy, it is important that surgical strategies must be decided according to both physical and cancerous conditions. Hence, various surgical procedures have been reported to date. The authors experienced two cases with cancer occurring in the reconstructed gastric tube after Ivor-Lewis esophagectomy. One was subsequent primary gastric cancer, and the other was metastatic gastric cancer. Distal resection of the gastric tube including the dissection of the right gastroepiploic vessels was carried out in both cases. Vascular reconstruction by utilizing microsurgery technique was attempted for each case, but failed in one case. After surgery, four sessions of endoscopic examinations were carried out. In the early period, we could identify mucosal ischemic change in the remnant gastric tube in the case without successful vascular reconstruction. On the contrary, no ischemic change was revealed in the other with successful vascular reconstruction. Hence, we came to the conclusion that vascular reconstruction must be added to the cases, which undergo distal resection of the reconstructed gastric tube with regional vascular dissection.     

Development of stereotactic irradiation system of body tumors under respiratory gating

Stereotactic radiosurgery for body tumors is hampered by the difficulties in body fixation and respiratory motions of the tumor. We have developed a Microton-based system for the stereotactic irradiation of body tumors, which delivers radiation at a predetermined respiratory phase. The patients are fixed non-invasively in the custom-made bed, and CT images are obtained. The isocentor is calculated with reference to those images and is marked onto the patient's skin and the custom-made bed. The patient lying on the bed is transferred to the treatment couch of the Microtoron. After reproducing the isocenter, actual treatment is started. The treatment couch as well as the gantry move automatically around the isocenter according to the treatment planning. The circular collimator moves by computer control to reduce geometrical errors to less than 0.5 mm, which is evoked by gantry movement. Respiratory movement of the abdominal wall is measured by laser displacement monitor. The Microtron delivers X-rays at a predetermined respiratory phase with a lag time of 20 msec after the on-signal from the monitor.