• The Korean Journal of Physiology and Pharmacology
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• v.4 no.1
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• pp.1-8
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• 2000

To investigate the contributions of intrinsic membrane properties to the spontaneous activity of medial vestibular nucleus (MVN) neurons, we assessed the effects of blocking large and small calcium-activated potassium channels by means of patch clamp recordings. Almost all the MVN neurons recorded in neonatal $(P13{\sim}P17)$ rat were shown to have either a single deep after-hyperpolarization (AHP; type A cells), or an early fast and a delayed slow AHP (type B cells). Among the recorded MVN cells, immature action potential shapes were found. Immature type A cell showed single uniform AHP and immature B cell showed a lack of the early fast AHP, and the delayed AHP was separated from the repolarization phase of the spike by a period of isopotentiality. Application of apamin and charybdotoxin (CTX), which selectively block the small and large calcium-activated potassium channels, respectively, resulted in significant changes in spontaneous firings. In both type A and type B cells, CTX (20 nM) resulted in a significant increase in spike frequency but did not induce bursting activity. By contrast, apamin (300 nM) selectively abolished the delayed slow AHP and induced bursting activity in type B cells. Apamin had no effect on the spike frequency of type A cells. These data suggest that there are differential roles of apamin and CTX sensitive potassium conductances in spontaneous firing patterns of MVN neurons, and these conductances are important in regulating the intrinsic rhythmicity and excitability.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.1
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• pp.17-20
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• 2004

PTEN (phosphatase and tensin homolog) is a dual specific phosphatase antagonizing phosphoinositide 3-kinase activity, and has first been cloned as a tumor suppressor for glioma. Although the role of PTEN as a tumor suppressor has been well studied, little is known about signaling mechanisms regulating expression and/or activity of PTEN in the central nervous system. In this study, we investigated whether PTEN expression is regulated by sensory deprivation. P5 rat pups were unilaterally naris-closed, and olfactory bulbs were immunohistochemically analyzed with PTEN antibody at the $7^{th}$ day after naris closure. PTEN immunoreactivity was found to be down-regulated in both glomerular, external plexiform and subependymal cell layers, suggesting that odor deprivation signals down-regulate expression of PTEN in the olfactory bulb. To the best of our knowledge, this is the first report to suggest that PTEN expression is regulated by sensory deprivation signals in neonatal rats.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.4
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• pp.952-957
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• 2003

To certify the protective effect of herbal medicine against oxygen free radical-induced myocardiotoxicity, cytotoxicity was measured using LDH activity and TBARS assay in the presence of Jisilhaebaekgyejitang(JHGT) extracts or single constituents of this prescription, In the present study, xanthine oxidase/hypoxanthine (XO/HX) resulted in a cell damage such as increases in LDH activity in culture medium and lipid peroxidation in cultured myocardial cells. In the effect of JHGT extract and its single constituents, which are Fructus Ponciri Seu Aurantii Immaturus (FPSAI), Cortex Magnoliae Officinalis (CMO), Bulbus Allii Macrostemi (BAM), Ramulus Cinnamomi (RC) and Fructus Trichosanthis (FT), they showed the prevention from the XO/HX-induced cardiotoxicity by the decrease of LDH activity and lipid peroxidation. From these results, they show that XO/HX is cardiotoxic in cultured myocardial cells derived from neonatal rat, and it suggests that JHGT, FPSAI, PT, CMO, BAM, RC and FT extracts are positively effective in the blocking in XO/HX-induced cardiotoxicity.

• Applied Microscopy
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• v.23 no.1
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• pp.56-76
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• 1993

To investigate the histogenesis of tracheal epithelium in Sprague-Dawley strain rat, the author has used the fetal rats at the 16th, 18th, 20th and 22nd prenatal day and neonatal rats at the 1st and 7th day as well as rats at age of 5, 10 and 15 weeks after birth as experimental animals. Specimens were double stained with uranyl acetate and lead citrate for electron microscopic study. The results obtained were as follows; 1. At the 16th day of gestational age, ciliated cells were found in tracheal epithelium and light and dark ciliated cells possessing numerous mitochondria and smooth endoplasmic reticulum in the cytoplasm at the 22nd day of gestational age of the rat are observed. 2. At the 16th day of gestataional age, basal cells lying upon the basement membrane and having large numbers of glycogen particles in the cytoplasm, were found and at the 22nd day of gestational age, basal cells possessing numerous polysomes in the cytoplasm were observed. 3. At the 20th gestational age of the rat, microvillous cells possessing many rough endoplasmic reticulum and mitochondria as well as microvilli protruding into the lumen were found in tracheal epithelium. 4. At the 5th week after birth brush cell having profound filamentous strands and many pinocytic vesicles in the cytoplasm, was visible in the tracheal epithelium. 5. At the 15th week after birth large proportions of tracheal epithelium were lined with ciliated cells. Cosequently it is suggested that pseudostratified ciliated columnar epithelium was differentiated at the 16th day of gestational age, in addition cytoplasmic organelles of the microvillous and basal cells were matured at the 20th and 22nd gestational age, respectively and most of the part of the tracheal epithelium was lined with ciliated cells at the 15th week after birth.

• Clinical and Experimental Pediatrics
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• v.51 no.10
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• pp.1102-1111
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• 2008

Purpose : Resveratrol, extracted from red wine and grapes, has an anti-cancer effect, an antiinflammatory effect, and an antioxidative effect mainly in heart disease and also has neuroprotective effects in the adult animal model. No studies for neuroprotective effects during the neonatal periods have been reported. Therefore, we studied the neuroprotective effect of resveratrol on hypoxic-ischemic brain damage in neonatal rats via anti-apoptosis. Methods : Embryonic cortical neuronal cell culture of rat brain was performed using pregnant Sprague-Dawley (SD) rats at 18 days of gestation (E18) for the in vitro approach. We injured the cells with hypoxia and administered resveratrol (1, 10, and $30{\mu}g/mL$) to the cells at 30 minutes before hypoxic insults. In addition, unilateral carotid artery ligation with hypoxia was induced in 7-day-old neonatal rats for the in vivo approach. We injected resveratrol (30 mg/kg) intraperitoneally into animal models. Real-time PCR and Western blotting were performed to identify the neuroprotective effects of resveratrol through anti-apoptosis. Results : In the in vitro approach of hypoxia, the expression of Bax, caspase-3, and the ratio of Bax/Bcl-2, indicators of the level of apoptosis, were significantly increased in the hypoxia group compared to the normoxia group. In the case of the resveratrol-treated group, expression was significantly decreased compared to the hypoxia group. And the results in the in vivo approach were the same as in the in vitro approach. Conclusion : The present study demonstrates that resveratrol plays neuroprotective role in hypoxic-ischemic brain damage during neonatal periods through the mechanism of anti-apoptosis.

• Neonatal Medicine
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• v.15 no.1
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• pp.32-37
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• 2008

Purpose : Perinatal asphyxia is an important cause of neonatal mortality and subsequent lifelong neurodevelopmental handicaps. Although many treatment strategies have been tested, there is currently no clinically effective treatment to prevent or reduce the harmful effects of hypoxia and ischemia in humans. In the clinical setting, maternal hyperthermia induces adverse effects on the neonatal brain, but recent studies have shown that hyperthermic pretreatment (PT) plays some role in hypoxic-ischemic (HI) injuries of the developing brain. The present study investigated the effect of hyperthermic PT on HI brain injuries in newborn rats. Methods : HI was produced in 7-day-old neonatal rats by unilateral common carotid artery ligation, followed by hypoxia with 8% oxygen at $38^{\circ}C$ for 2 hours. Twenty-four hours before HI, one-half of the pups were exposed to a $40^{\circ}C$ environment for 2 hours. The severity of the brain injury was assessed 7 days after the HI. Results : Hyperthermic PT reduced the gross and histopathologic findings of brain injury from 64.7 to 31.2% (P<0.05). There were no differences in location and severity of injury between the pretreated and control brains. Conclusion : These findings indicate that hyperthermic PT provides neuroprotective benefits on HI in the developing brain. Also, these findings suggest maternal hyperthermia may have protective effect on perinatal HI brain injuries.

• Journal of Nutrition and Health
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• v.17 no.3
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• pp.199-209
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• 1984

Pregnant rats were fed a pyridoxine deficient diet during the gestation and lactation. DEF I group received the deficient diet from delivery ; DEF II group, from the 15 th day of gestation. Body and brain weights, brain protein, DNA, RNA, plasma GOT and GPT, and catecholamines were measured. Effect of MAO inhibiting drug, pargyline, was determined. Brain protein, DNA, and RNA of offsprings of deficient groups were significantly lower than the control group, but RNA/ DNA, brain weight/DNA, and protein/DNA show that cell number were more affected than cell size by the pyridoxine deficiency during the 3rd week of gestation and lactation. Plasma GOT activities were more significantly different than plasma GPT between the control and deficient group. Brain norepinephrine of offsprings of deficient group were significantly lower than the control, but brain dopamine content was not significantly different from the control. At 2nd and 3rd week, norepinephrine was significantly depressed in deficient groups. Pargyline treatment affected a 1.2 fold increase in catecholamines in 3hr while the control had a 1.5 fold increase. Thus norepinephrine and dopamine synthesis was depressed in the deficient groups. Dopaminergic neurons may be less dependent on pyridoxine level than neurons from norepinephrine. Pyridoxine deficiency in maternal diet is not so critical to brain catecholamines of offspring except to the neonatal rats.

• Archives of Pharmacal Research
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• v.27 no.11
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• pp.1154-1160
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• 2004

We investigated the neurotoxic effects of capsaicin (CAP) on pain sensitivity and on the expression of capsaicin receptor, the vanilloid receptor (VR1), in rats. High-dose application of CAP has been known to degenerate a large fraction of the sensory neurons. Although the neurotoxic effects of CAP are well documented, the effects of CAP on the vanilloid receptor (VR1) are not yet known. In this paper, we investigated the effects of high-dose application of CAP on the expression of VR1 in rats. Thermal and mechanical pain sensitivity was reduced when neonatal rats were treated with a high dose of CAP. This reduction of pain sensitivity was significantly decreased after initiating carrageenan-induced inflammation. The expression of VR1 in dorsal root ganglia (DRG) isolated from the CAP-treated rats was reduced compared to that from the vehicle-treated rats. Therefore, we can conclude that the neurotoxic effect of CAP is related to the decrease of VR1 expression.

• Biomedical Science Letters
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• v.11 no.2
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• pp.211-219
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• 2005

Trigeminovascular system plays an important role for the cerebral memodynamics. The aim of this study was to investigate the alterations in cerebrovascular reactivity by trigeminovascular system injury in rats. Trigeminovascular system of male Sprague-Dawley rats was injured by either denervation of nasocilliary nerve or neonatal capsaicin treatment. Trigeminovascular system was stimulated by controlled hemorrhagic hypotension or somatosensory (whisker) stimulation. Changes in regional cerebral blood flow (rCBF) and pial arterial diameter were continuously measured by laser-Doppler flowmetry and videomicroscopy, respectively. Nitric oxide synthase (NOS) activity in cerebral cortex was determined by measuring the conversion of $L-^3H-arginine\;to\;L-^3H-citrulline$. Cyclic GMP levels in cerebral cortex and pial artery were determined using the cyclic GMP $^{125}I$ scintillation proximity assay system. rCBF autoregulation was impaired or almost abolished by trigeminovascular system injury. rCBF response to whisker stimulation was significantly attenuated by trigeminovascular system injury. NOS activity as well as cyclic GMP level in cerebral cortex and pial artery were significantly reduced in the group of trigeminovascular system injury. These results suggest that trigeminovascular system injury causes prominent alterations in cerebrovascular reactivity, and that NO, which is generated by neuronal NOS in the trigeminovascular system, is implicated in the regulation of rCBF.

• Journal of Animal Science and Technology
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• v.55 no.6
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• pp.521-530
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• 2013

Direct cell-cell communication via the transfer of small molecules between neighboring cells in tissue is accomplished by gap junctions composed of various connexins (Cxs). Proper postnatal development of the epididymis is important for acquisition of male reproduction. The epididymal epithelium is composed of several cell types, and some of these cells are connected by gap junctions. The present study was conducted to determine the presence of Cx transcripts in the corpus and cauda epididymis. In addition, transcriptional changes of Cxs expressed during different postnatal stages were examined by real-time PCR analysis. In both epididymal regions, the same nine Cx transcripts of thirteen Cxs tested were detected. In the corpus epididymis, the highest levels of Cxs31.1 and 37 transcripts were observed at 45 days of age, and amounts of Cxs26, 30.3, and 32 transcripts increased with age and subsequently decreased in the elderly. Expression of Cx31 was greatly increased in the adult and elder stages, while Cxs40, 43, and 45 were abundant in the early postnatal stages. In the cauda epididymis, expression of Cxs26, 30.3, 31.1, 37, and 40 reached the highest levels at 5 months of age. The levels of Cxs31 and 32 mRNAs fluctuated throughout the postnatal period. The amounts of Cxs43 and 45 transcripts were more abundant during the late neonatal and prepubertal ages than later ages. These findings suggest that regional specification of the epididymis is partly regulated by differential expression of Cx genes during the postnatal developmental period.