• Development and Reproduction
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• v.24 no.4
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• pp.287-296
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• 2020

The absence of functional estrogen receptor α (Esr1) results in an overgrowth of the epididymal fat, as observed in estrogen receptor α knockout (ERαKO) mouse. The present research was aimed to evaluate expression of various molecules associated with adipocyte differentiation and maturation in the epididymal fat of ERαKO mouse at several postnatal ages by using quantitative real-time polymerase chain reaction. The highest transcript levels of all molecules were detected at 12 months of postnatal age, except leptin which the mRNA level was increased at 5 months of age and was unchanged until 12 months of age. The expression levels of CCAAT enhancer binding protein (Cebp) alpha, androgen receptor, and lipoprotein lipase were decreased at 5 months of age but increased at about 8 months of age. The mRNA levels of Cebp gamma and sterol regulatory element binding transcription factor 1 remained steady until 8 months of age. Continuous increases of transcript levels during postnatal period were found in Cebp beta, estrogen receptor (ER) beta, fatty acid binding protein 4, and delta like non-canonical Notch ligand 1. The increases of peroxisome proliferator-activated receptor gamma and adiponectin mRNA levels were detected as early as 8 months of age. The levels of fatty acid synthase and resistin transcript at 5 and 8 months of age were lower than that at 2 months of age. These findings show the aberrant expression patterns of genes related to adipocyte differentiation and maturation in the postnatal epididymal fat pad by the disruption of ER alpha function.

• Applied Microscopy
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• v.24 no.4
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• pp.32-40
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• 1994

This study was undertaken to study the morphological changes of rat synapses during early postnatal periods. Neonatal rats were grouped by 1st, 2nd, 3rd, 4th and 6th postnatal weeks, and we observed the ultrastructural pattern of the synapses in the external plexiform layer of olfactory bulbs by electron microscopy. The results were as follows; 1. The numbers of synapses, lengths of synaptic thickenings and amounts of synaptic vesicles were markedly increased in the external plexiform layer during four postnatal weeks. 2. There was a tendency of increasing the proportion of the asymmetric synapse and the curved synapses during maturation. From the above results, it is suggested that the size of synapse is increasing during maturation, and at the same time the asymmetric synapses are formed from the symmetric type and the curved synapses are from the plane type.

• Development and Reproduction
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• v.22 no.4
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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.

• BMB Reports
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• v.34 no.6
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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.

• International Journal of Oral Biology
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• v.43 no.4
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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.

• Molecules and Cells
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• v.46 no.11
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• pp.672-674
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• 2023

Schematic diagram of the interaction between the intestinal muscularis externa (MMΦ) macrophages and the enteric nervous system (ENS) neurons during different developmental periods. At the early postnatal stage, MMΦs play a critical role in ENS maturation and refinement through synaptic pruning and enteric neuron phagocytosis. In addition, during the adult stage, a specific MMΦ subset named neuron-associated (NA)-MMΦ, supports enteric neuronal survival and functions. Conversely, enteric neurons promote the phenotypic MMΦ changes by secreting transforming growth factor-β (TGFβ), transitioning them from a phagocytic phenotype in the early postnatal period to a neuroprotective and immune-surveillant phenotype in the young adult period. Disruptions in these interactions could lead to alterations in the enteric neuron numbers, ultimately resulting in reduced gut motility.

• Journal of Life Science
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• v.17 no.10
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• pp.1347-1353
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• 2007

The changes of glycoconjuagates (GCs) in rat kidney due to maturation were studied from samples of fetal and postnatal kidneys by lectin histochemistry. Rat kidneys of perinatal ages and adults were fixed in 4% paraformaldehyde and were stained with nine kinds of biotinylated lectins. The immature forms of the renal developmental stage such as vesicles and ureteric bud were observed in the cortex as late as day 14 of postnatal life, but the histological appearance of the weaning kidney was similar to that observed in adults. As for histochemical properties of GCs in the glomeruli, Con A affinity tended to increase with aging, but both RCA-1 and LCA affinities showed a transient increase in immature glomeruli of neonatal rats. DBA affinity with SBA, PNA, BSL-1 and RCA-1, additional Con A one in proximal tubule, were increased in both proximal and distal tubules according to maturation. In contrast to this, transient intensive LCA affinity were demonstrated in immature proximal and distal tubule of neonatal rats. In the collecting tubules, DBA, SBA, PNA and sWGA affinities tended to increase according to maturation, but transient increase for BSL-1, RCA-1 and LCA affinities were detected in neonatal rats. The present results suggest that the mature glycosylation pattern of the kidney undergoes profound changes during maturation and is probably associated with functional maturation of the kidney.

• Progress in Medical Physics
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• v.16 no.4
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• pp.214-219
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• 2005

As part of Korean retinal prosthesis project, we have provided preliminary experimental results regarding voltage parameters for the stimulation of chemically degenerated rabbit retina. Since our APB-treated chemically degenerated retina is only ON-pathway blocked, now we switch our experiments to more appropriate retinal degeneration model, genetically degenerated retina model (RD mouse: rd/rd (C3H/HeJ)). Before studying with RD mouse, we started control experiments with normal SD rat to understand characteristics of retinal ganglion ceil activity with postnatal maturation in rodents. Ganglion cell activities were recorded with 8${\times}$8 multi-electrode array. Moving spontaneous bursts appeared until postnatal day of 15. During pre-eye opening period, no light evoked response appeared. After postnatal day of 2 weeks (post-eye opening period), ON-, OFF- and ON/OFF response appeared. The fractional distributions of ON, OFF, and ON/OFF ganglion cell is about $40\%,\;50\%$, and $5\%$. The percentage ($\%$) of light evoked response in each dorso-temporal, ventral, and dorso-nasal area of eye is about $50\%,\;37.5\%$ and $12.5\%$, respectively. We concluded that the optimal period for experiment in rodent is about postnatal day of 2${\~}$3 weeks.

• Journal of Animal Science and Technology
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• v.55 no.4
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• pp.249-255
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• 2013

Intercellular interactions are important for the proper development and regulation of tissue function. This is especially necessary in the epididymis, a part of male reproductive tract where sperm become mature and acquire their fertilizing capacity. The caput region of the epididymis consists of several types of cells, including principal, basal, and apical cells. Direct intercellular communication is thus required to precisely regulate the functions of the caput epididymis. In this regard, connexin (Cx) is a molecule that forms channels, which allow the direct exchange of small molecules between cells, enabling intercellular communication. In this study, the expression of Cx isoforms in the caput epididymis at different postnatal ages was determined by using quantitative real-time polymerase chain reaction analysis. Nine of 13 Cx isoforms were detected. The transcript levels of Cx30.3, 31, 31.1, 32, and 40 were highest at 45 days of age, while the expression of Cx43 and 45 gradually decreased with age. A substantial fluctuation of Cx26 expression was detected, with significant decreases before and during puberty, followed by a transient increase at adult-hood and rapid decreases at an old age. A significant increase in Cx37 transcript was observed at 25 days of age, followed by gradual decreases at adult and old ages. These results indicate the significant differential expression of various Cx isoforms in the caput epididymis during postnatal development. It further suggests that the functional regulation and developmental maturation of the caput epididymis are highly related to the postnatal age-related differential expression of Cx isoforms.

• Development and Reproduction
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• v.23 no.3
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• pp.213-221
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• 2019

The epididymal fat of mouse is a part of visceral fat deposit and is divided into the distal or proximal part based on its histochemical characteristics. Even though the formation of the epididymal fat pad begins before the birth, a detailed adipogenic procedure of the epididymal fat has not been revealed. The epididymal fat pad becomes enlarged and expended with age, and expressional changes of numerous genes are associated with the maturation of fat tissues. In the present research, expressional patterns of adipose tissue-related genes in the distal epididymal fat of mouse at 2, 5, 8, and 12 months of postnatal age were determined by a quantitative real-time polymerase chain reaction (PCR) analysis. The lowest transcript levels of fatty acid binding protein 4 (Fabp4), lipoprotein lipase (Lpl), delta like non-canonical Notch ligand 1 (Dlk1), peroxisome proliferator-activated receptor gamma (Pparg), leptin (Lep), adiponectin (Adipoq), and resistin (Retn) were detected at 2 months of age, except fatty acid synthase (Fasn) showing the lowest level at 5 months of age. Even though expression of Lep and Fabp4 were gradually increased until 12 months of age, significant increases of Pparg and Adipoq transcript levels were continued until 8 months of age. The transcript levels of Lpl, Rent, Dlk1, and Fasn were significantly increased at 8 months of age, compared with those at 2 months of age. The current findings suggest that the expansion of the distal epididymal fat of mouse during postnatal period would be companied with differential expression of various adipocyte-associated molecules.