• The Korean Journal of Physiology and Pharmacology
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• 제1권4호
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• pp.355-366
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• 1997

Although cerebellar Purkinje cells display spontaneous electrical activity in vivo and in slice experiments, the mechanism of the spontaneous activity generation has not been clearly understood. The aim of this study was to investigate whether cerebellar Purkinje cells of postnatal rats generate spontaneous electrical activity without synaptic inputs. Dissociated cerebellar Purkinje cells were used for reducing synaptic inputs in the present study. Cerebellar Purkinje cells with dendrites were dissociated from postnatal rats using enzymatic treatment followed by mechanical trituration. Spontaneous electrical activities were recorded from dissociated cells without any stimulus using whole-cell patch clamp configuration. Two types, spontaneously firing or quiescent, of dissociated Purkinje cells were observed in postnatal rats. Both types of cells were identified as Purkinje cells using immunocytochemical staining technique with anti-calbindin after recording. Spontaneously active cells displayed two patterns of firing, repetitive and burst firings. Two thirds of dissociated Purkinje cells displayed repetitive firing and the rest of them did burst firing under same recording condition. Repetitive firing activities were maintained even after further isolation using either physical or pharmacological techniques. Neither high magnessium solution nor excitatory synaptic blockers, AP-5 and DNQX, block the spontaneous activity. These results demonstrate that spontaneous electrical activity of isolated cerebellar Purkinje cells in postnatal rats is generated by intrinsic membrane properties rather than synaptic inputs.

• Toxicological Research
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• 제17권1호
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• pp.17-25
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• 2001

Korean ginseng products have been fumigated with ethylene oxide (EO) for sterilization and prolongation of storage periods. However, there had been controversies indicating that consumption of EO treated foods might cause harmful effects in human. In Korea, the use EO gas for sterilization of food was banned in 1991. Since then, irradiation technique has been developed as an alternative. This study was carried out to evaluate the safety of irradiated ginseng on peri- and postnatal developmental toxicity in rats. Either EO gas fumigated or gamma-irradiated ginseng was administered to pregnant Wistar rats by oral gavage from gestational day 16 to postnatal day 21. The amount of irradiation used in this study was 5, 10 and 30 kGy, respectively. There were no treatment related changes of dams in deaths, clinical signs, and parturition. No treatment related changes in food consumption, body/organ weight and lactation of dams were observed. Also, no F1 fetuses in external abnormality, physical development, reflex/sensory junctions and behavioral development were found. The results of this study showed that gamma-irradiated ginseng, up to 30 kGy, has no adverse effects on the peri- and postnatal development of rats.

• Toxicological Research
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• 제11권1호
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• pp.91-101
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• 1995

A perinatal and postnatal study of KTC-1, a new semisyntheitic rifamycin antituberculous drug, was conducted in Sprague-Dawley rats. Dosages of KTC-1 0, 12, 27.6, and 63.5 mg/kg/day were administered to dams orally by gavage from day 17 of gestation to day 21 of lactation. All pregnant rats were allowed to deliver naturally for postnatal examination of their offspring. At 63.5 mg/kg/day, weakness, dark-red discharge around eyes, a loss in body weight, and a decrease in food and water consumption were observed in dams. An increase in the weight of adrenal gland and spleen, and a decrease in the weight of kidney and heart were also found. An increase in neonatal deaths during the lactation period, a loss in body weight, a delay in physical development, a decrease in traction ability, an increase in the number of errors and the time required for the multiple T-maze trial were found in F1 offspring. In addition, an increase in the incidence of visceral variations and retarded ossification were observed in F1 4 day old rats. An increase in the incience of skeletal anomalies was seen in F2 fetuses. There were no sings of maternal toxicity or embryotoxicity at 12 and 27.6 mg/kg/day. From the results mentioned above, it can be concluded that the no-effect dose levels(NOELs)for dams, F1 offspring, and F2 fetuses are 27.6 mg/kg/day.

• Toxicological Research
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• 제3권1호
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• pp.55-63
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• 1987

A Peri-and Postnatal Study was Carried out to examine the effects of rHuIFN-${\alpha}A$, produced by gene-manipulated E. coli, on offsprings of Wistar rats. The substance was administered intraperitoneally to dams at dose levels of $1{\times}10^5$, $4{\times}10^5$ and $1.2{\times}10^6$ I.U/kg/day during the period from day 17 of gestation to day 21 after delivery. All the pregnant dams were allowed to deliver naturally, and the postnatal development of the offsprings was observed. No noticeable toxic effects and pathological changes on dams were observed, and no detectable variations in postnatal development of offsprings occured.

• The Korean Journal of Physiology and Pharmacology
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• 제4권3호
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• pp.169-175
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• 2000

To learn the developmental changes in intrinsic electrophysiological properties of the second order taste neurons, whole cell recordings from the developing nucleus of the solitary tract neurons were done in brainstem slices of postnatal rats. Rats aged from postnatal 0 to 21 days (P0-P21) were used, being divided into 3 age groups: postnatal first week (P0-P7 days), second week (P8-P14 days), and third week (P15-P21 days). Slices containing gustatory NTS were cut horizontally in the thickness of $300\;{\mu}m.$ Whole cell recordings were obtained from neurons in response to a series of hyperpolarizing and depolarizing current pulses. The intrinsic electrophysiological properties of the rostral NTS (rNTS) neurons were compared among the age groups. Depolarizing current pulses evoked a train of action potentials in all neurons of all age groups. The resting membrane potential and input resistance of the neurons did not show any significant differences during the postnatal 3 weeks. The time constant, however, decreased during the development. Duration of action potential measured at half maximum amplitude was longer in younger age groups. Both the maximum rate of rise and the maximum rate of fall in the action potential increased during the first 3 weeks postnatal. Electrophysiologically more than half neurons were type III. In summary, it is suggested that developmental changes in electrophysiological properties in rNTS occur during the first three weeks in rats.

• Clinical and Experimental Reproductive Medicine
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• 제39권4호
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• pp.144-152
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• 2012

Objective: Concerns are growing about the decrease in male reproductive health. Caffeine is one of the popular nutrients that has been implicated as a risk factor for infertility. In the present study, we examined whether in utero and lactational exposure to caffeine affects the reproductive function of the offspring of rats. Methods: Pregnant rats received caffeine via drinking water during gestation (26 and 45 mg/kg) and lactation (25 and 35 mg/kg). Body and reproductive organ weight, seminiferous tubule diameter, germinal epithelium height, sperm parameters, fertility rate, number of implantations, and testosterone level of the offspring were assessed from birth to adulthood. Results: Significant dose-related decreases were observed in the body and reproductive organ weight, seminiferous tubule diameter, and germinal epithelium height of the offspring. Sperm density had declined significantly in offspring of the low-dose and high-dose groups, by 8.81% and 19.97%, respectively, by postnatal day 150. The number of viable fetuses had decreased significantly in females mated with male offspring of the high-dose group at postnatal days 60, 90, 120, and 150. There were also significant reductions in testosterone levels of high-dose group offspring from birth to postnatal day 150. Conclusion: It is concluded that maternal caffeine consumption impairs gonadal development and has long-term adverse effects on the reproductive efficiency of male offspring rats.

• 한국농촌생활과학회지
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• 제5권2호
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• pp.125-134
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• 1994

This study was performed to observe the effects of dietary fat levels and sources on lipids contents and cellularities of liver, brain, and adipose tissue of early weaned rats. Male Sprague-Dawley rats were prematurely weaned from postnatal 17th day with the experimental diets differ in fat levels : low(5%), medium(10%), high(20%) and fat sources : butter, soybean oil, butter＋ soybean oil. On the postnatal 29th day, contents of total lipid, triglyceride, cholesterol and phospholipid of serum, liver, brain and adipose tissue were determined, and DNA was determined to assess the cell growth. Rats early weaned fed high fat diet showed lower total lipid and triglyceride levels in serum and liver than those fed medium or low fat diet Rats early weaned fed high fat diet had adipocytes of fewer number, but larger size than those of rats fed low or medium fat diets. Rats early weaned fed soybean oil diet had more adipocytes thu those fed butter diet. Rats normally weaned to commercial chow diet showed lower total lipid, triglyceride, and cholesterol levels in serum and liver, had fewer adipocytes than all early weaned rats except for rats fed high fat-butter diet. These results suggest that high fat-butter diet is ideal weaning diet at early weaning.

• 한국임상수의학회지
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• 제16권1호
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• pp.42-49
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• 1999

The reproductive effect of $Telazol^{\circledR}$ was studied in pregnant rats. Two different doses (20 or 40 mg/kg/day) were injected on days one of 3, 5 or 8 of pregnancy and 3 consecutive days of 3~5 or 5~7 in pregnant rats. On days 8 or 21, the rats were anesthetized, the cesarean section was performed, the uterus was carefully examined, and the numbers of corpora lutea, implantation sites and viable fetuses, fetal and placental weights and pre-and post-implantation losses in rats were surveyed. Simultaneously the concentrations of sodium and potassium of the plasma, uterine and amniotic fluids were determined. And gestation period in pregnant rats, postnatal offspring survival and body weight gains were evaluated. Administration of $Telazol^{\circledR}$ did not exert a bad influence upon body weight gains in pregnant rats. Reproductive indices were normal. The concentrations of sodium and potassium of the plasma, uterine and amniotic fluids in pregnant rats remained unchanged. Gestation period of rats, postnatal offspring survival and body weight gains were normal. It is concluded that $Telazol^{\circledR}$ is devoided of significant adverse reproductive effects in pregnant rats.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.296.2-296.2
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• 2002

Our previous study demonstrated that 2.3', 4.4'. 5- Pentachlorobiphenyl (PCB 118) showed an antiestrogenic activity in vitro and in vivo. In the present study. we examined the effect of PCB 118 on postnatal reproductive development in female rats. PCB 118 (0.001. 0.01 or 0.1 mg/kg/day) was administered to pregnant female SD rats from gestation day (GO) 6 to 18 via subcutaneous injection. and developmental parameters such as vaginal opening were determined. PCB 118 significantly delayed vaginal opening of female offsprings at dose of 0.1 ${\mu}g$/kg/day. whereas had no effects on body weights. In addition. in utero treatment of PCB 118 caused significant decreases in serum levels of E2, T3 and T4 in female oftsprings at certain doses on postnatal day (PND) 22. Our data of results indicate that in utero exposure to PCB 118 may postnatal reproductive development in female rat through its antiestrogenic activity.

• International Journal of Oral Biology
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• 제43권4호
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• pp.177-183
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• 2018

The objective of this study was to examine the expression pattern of Kelch-like ECH-associated protein 1 (Keap1) in the maxillary $2^{nd}$ molar germs of rats. We used the maxillary $2^{nd}$ molar germs in rats' pup at postnatal day 3 (bell stage), 6 (crown formation stage) and 9 (root formation stage). The investigation on mRNA and protein levels were done using reverse transcription - polymerase chain reaction and western blot. Localization of Keap 1 in the maxillary $2^{nd}$ molar germs were revealed through immunofluorescence staining. Keap1 from the maxillary 2nd molar germs were mostly manifested on postnatal day 3 and dramatically decreased on postnatal day 6 and 9 at mRNA and protein levels, while amelogenin and ameloblastin increased during the development of maxillary 2nd molar germs. During immunofluorescence analysis, the strong immunoreactivity against Keap1 was detected in the apical side of ameloblasts at the presecretory and secretory stages. However, Keap1 expression was hardly observed in the ameloblasts at the maturation stage. These results shows that Keap1 is strongly expressed in the presecretory and secretory ameloblasts of amelogenesis, and suggest that Keap1 may be a crucial molecule for the regulatory mechanisms tasked with the formation of enamel layer.