• 한국발생생물학회지:발생과생식
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• 제22권4호
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• pp.351-360
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• 2018

The adipogenesis is a maturation process of pre-adipocyte cell into mature lipid-filled adipocyte cell. The adipogenesis begins at the late prenatal stage and continues until the early postnatal age. Because the adipogenesis and formation of adipose tissue persist during postnatal period and are precisely regulated by the action of numerous gene products, the present research was attempted to determine the expressional patterns of adipose tissue-associated genes in the rat epididymal fat pad at different postnatal ages, from 7 days to 2 years of ages, using a quantitative real-time PCR analysis. The basal expression levels of CCAAT/enhancer binding protein gamma, sterol regulatory element binding transcription factor 1, fatty acid binding protein 4, adiponectin, leptin, and resistin at the early postnatal ages were significantly lower than those at the elderly ages, even though a fluctuation of expressional levels was observed at some ages. The lowest expressional level of delta like non-canonical Notch ligand 1 was detected at 44 days and 5 months of ages. The expression of peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$) was the highest at 44 days of age, followed by a diminished expression of $PPAR{\gamma}$ at the elderly ages. These results indicate the existence of a complex regulatory mechanism(s) for expression of adipose tissueassociated genes in the rat epididymal fat during postnatal period.

• 한국발생생물학회지:발생과생식
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• 제22권1호
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• pp.29-38
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• 2018

In the multicellular tissue, cell-cell interaction is important for a precise control of its function. The exchange of signaling molecules between adjacent cells via connexon allows the functional harmony of cells in the tissue. The present research was to determine the presence and expressional patterns of connexin (Cx) isoforms in the rat epididymal fat during postnatal development using quantitative real-time polymerase chain reaction (PCR) analysis. Of 13 Cx isoforms examined, expression of 11 Cx isoforms in the epididymal fat during postnatal development was detected. These Cx isoforms include Cx26, Cx31, Cx31.1, Cx32, Cx33, Cx36, Cx37, Cx40, Cx43, Cx45, and Cx50. Expressional levels of all Cx isoforms at 1 and 2 years of age were significantly higher than those at the early postnatal ages, such as 7 days, 14 days, and 24 days of ages. Except Cx33 and Cx43, the transcript levels of rest Cx isoforms at 1 year of age were significantly lower than that at 2 years of age. In addition, expressional patterns of Cx isoforms between 7 days and 5 months of ages generally varied according to the isoform. The existence of various Cx isoforms in the rat epididymal fat has been identified and expression of each Cx isoform in the epididymal fat during postnatal development has shown a particular pattern, distinguishable from the others. To our knowledges, this is the first report showing expressional patterns of Cx isoforms at transcript level in the epididymal fat at various postnatal ages.

• Applied Microscopy
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• 제27권4호
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• pp.347-355
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• 1997

These studies were performed to observe the morphological changes of synapses in the visual cortex of rat during early postnatal development. Specimens of the visual cortex were taken from rats (Sprague Dawley) at 1, 3, 7, 14 and 21 days of age, and prepared for silver impregnation and electron microscopy. The number of synapse and the length of postsynaptic thickening were increased progressively with age, especially 14 and 21 days. The number of dendritic spine was increased conspicuously on postnatal days 14-21. And asymmetic, curved and axo-spinous synapses were increased markedly at the same ages. The present findings suggest that spurt of synaptogenesis in the rat visual cortex occurs during early postnatal development, especially in second to 3rd week period and asymmetric and/or curved axo-spinous synapse is a matured form of synapse with advanced age.

• Journal of Animal Science and Technology
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• 제54권6호
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• pp.419-425
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• 2012

The coordinated action of the detrusor muscle cells in the urinary bladder is governed by cell-cell communication through gap junction, consisted of connexin (Cx) molecules. Even though a number of researches have been mostly focused on expressional changes of a few Cx isoforms in clinically dysfunctional condition of the bladder, less attention has been paid for investigation of Cx isoforms present in the bladder. Using real-time PCR analysis, the present study examined Cx isoforms expressing in the male rat bladder during postnatal period. Also, expressional patterns of Cx isoforms were evaluated in the bladder at different postnatal ages. Of a total of 13 Cx isoforms tested in the present study, we were able to detect mRNAs of 6 Cx isoforms in the rat urinary bladder, including Cxs 31, 31.1, 32, 37, 40, and 45. The transcript levels of Cxs 31, 31.1, 37, 40, and 45 were gradually increased from 1 week of age until 25 days of age, followed by transient decreases at 45 days of age. However, abundance of Cx32 transcript was drastically increased at 15 days of age, followed by a sharp drop at 45 days of age. These results indicate that differential expression of Cx isoforms in the bladder during postnatal development would be necessary for maintaining proper function of the bladder. A question remains to be answered if significant decreases of transcript levels of some Cx isoforms at the elderly are associated with age-dependent dysfunction of the bladder.

• 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.

• Journal of Animal Science and Technology
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• 제55권6호
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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.

• BMB Reports
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• 제34권6호
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• pp.573-577
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• 2001

The mammalian heart is known to undergo significant mechanical changes during fetal and neonatal development. The objective of this study was to define the ontogeny of the ryanodine receptor/$Ca^{2+}$ release channel and SERCA that play the major roles in excitation-contraction coupling. Whole ventricular homogenates of fetal (F) (19 and 22 days in gestation), postnatal (N) (1 and 7 days postnatal), and adult (A) (5 weeks postnatal) Sprague-Dawley rat hearts were used to study [$^3H$]ryanodine binding and oxalate-supported $^{45}Ca^{2+}$ uptake. For the ryanodine receptor, the major findings were: (1) The ryanodine receptor density, as determined by maximal [$^3H$]ryanodine binding ($B_{max}$), increased 3 fold between the F22 and A periods ($0.26{\pm}0.1$ vs. $0.73{\pm}0.07$ pmoles/mg protein, p<0.01), whereas there was no significant change during the F22 and N1 development phases ($0.26{\pm}0.1$ vs. $0.34{\pm}0.01$). (2) Affinity of the ryanodine receptor to ryanodine did not significantly change, as suggested by the lack of change in the $K_d$ during the development and maturation. For SERCA, changes started early with an increased rate of $Ca^{2+}$ uptake in the fetal periods (F19: $8.1{\pm}1.1$ vs. F22: $19.3{\pm}2.2$ nmoles/g protein/min; p<0.05) and peaked by 7 days (N7) of the postnatal age ($34.9{\pm}2.1$). Thus, we conclude that the quantitative changes occur in the ryanodine receptor during myocardial development. Also, the maturation of the $Ca^{2+}$ uptake appears to start earlier than that of the $Ca^{2+}$ release.

• 한국전문물리치료학회지
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• 제16권2호
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• pp.50-58
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• 2009

The purpose of this study was to test that motor skill training enhance motor function and cerebellar development. Using an animal model of fetal alcohol syndrome-which equates peak blood alcohol concentrations across developmental period-critifical periods for the effect of alcohol on body and cerebellar weigh was examined. The effect of motor skill training on motor function and cerebellar development of rat exposed alcohol on postnatal days 4 through 10 were studied. Newborn rats were assigned to one of two groups: (1) Control group (CG), via artificial rearing to milk formula and (2) experimental groups (EG), via 4.5g/kg/day of ethanol in a milk solution. After completion of the treatments, the pups were fostered back to lactating dams, and wearing they were raised in standard caged until they were postnatal 48 days. Rats from experimental group of postnatal treatment then spent 10 days in one of two groups: Experimental group II (EGII) was had got motor skill training (training traverse a set of 6 elevated obstacles) for 4 weeks. Experimental group I (EGI) was not trained. Before sacrificing, the rat got examined two behavioral test, body weigh and cerebellar weigh, then coronal sections were processed. The section was investigated the Purkije cell in the cerebellum using light microscope. The results of this study were as follows. 1. In body weight test, the outcome of alcohol groups were significantly lower than the normal group. 2. In cerebellar weight test, the outcome of EGI were significantly lower than CG and EGII. 3. In motor behavioral test, the outcome of EGI was significantly lower than NG and EGII. 4. In Purkinje cells counting test, the outcome of EGI was significantly lower than the NG and EGII. These result suggest that improved motor function induced by motor skill training after postnatal exposure is associated with dynamically altered expression of Purkinje cells and that is related with cerebellar function. Also, these data can potentially serve as a model for therapeutic intervention.

• Animal Bioscience
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• 제34권10호
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• pp.1717-1722
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• 2021

Objective: Stroking calves during the postnatal period could effectively improve human-calf relationships. The objective of this study is to examine how daily calf stroking frequency during the postnatal period affects the establishment of human-calf relationships. Methods: Six calves were stroked by a trainer for 6 minutes once daily for 5 days after birth (D1). Six calves were stroked by a trainer for 3 minutes twice daily for 5 days after birth (D2). A further four calves were stared at but not stroked as the control group. The overall stroking or staring duration was the same for all groups, at 6 min/d and 30 min over 5 days. The tests for reactions to the stationary trainer in an unfamiliar environment and avoidance distance measurements for an approaching trainer were conducted at 1 month and 3 months after the treatment. Results: Calves in both stroking groups approached significantly closer to the stationary trainer, vocalized less, and looked at the trainer shorter than the control group at 1 month. However, at 3 months, there was no significant difference between the D1 and the control group, whereas the D2 approached significantly closer to the trainer and vocalized less, and looked at the trainer for a shorter time than the control group. For the avoidance distance, the trainer could approach closer to both stroking groups than the control at 1 month, however, there was no difference among groups at 3 months. Conclusion: Our results suggested that the difference in the calf stroking procedure affected the established human-calf relationships, even though the total stroking duration was the same for all stroked calves. It is likely to be more effective to stroke more frequently than intensively when the aim is to establish better human-calf relationships within limited labor time.

• 대한수의학회지
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• 제52권1호
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• pp.1-8
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• 2012

Histochemical patterns of lectin binding during development of the rat vomeronasal organ (VNO) were studied to determine whether glycoconjugates are differently expressed after birth. Three types of lectins, Dolichos biflorus agglutinin (DBA), wheat germ agglutinin (WGA), and Ulex europaeus agglutinin I (UEA-I), were studied histochemically in the rat VNO at various stages post-birth: postnatal days 1 and 7, the preweaning period (4 weeks after birth), and at sexual maturity (8 weeks after birth). The free border of the vomeronasal sensory epithelium was positive for both WGA and UEA-I in rats of all ages; whereas, VNO receptor cells and supporting cells were positive only for both WGA and UEA-I from 4 weeks after birth. DBA reactivity was detected in the free border but less so in receptor cells and supporting cells. WGA and UEA-I, but not DBA, showed similar patterns in various ages. In the Jacobson's gland, WGA, UEA-I and DBA were detected in some acini from 4 weeks after birth but not at postnatal days 1 or 7. Collectively, reactivity for three lectins, WGA, UEA-I and DBA, increased in receptor cells and gland acini during postnatal development, possibly contributing to the enhanced chemoreception in rats.