Rats Of Different Ages Research Articles

Correlations between Metabolic Parameters, Blood Cytokine Levels, and Behavioral Parameters in Male and Female Rats of Different Age after Intrauterine Stress.

We studied interrelationships between behavioral parameters, metabolic processes, and cytokine content in the blood of male and female rats at different stages of postnatal ontogeny after intrauterine stress (mothers were forced to swim in cold water from the 10th to the 16th day of pregnancy). Correlations between behavioral and metabolic parameters in prenatally stressed rats were revealed at an earlier age (day 21 of life) than in controls. In comparison with intact rats, in males exposed to intrauterine stress no relationships between these parameters were revealed at older age, while in females, their direction and character change on day 60 of life. In prenatally stressed males, correlations of the blood levels of IL-6 were revealed: inverse relationships with behavioral parameters on the days 21 and 30 and direct relationships with metabolic parameters on day 60 of life. In prenatally stressed females on day 30 of life, we observed negative correlations between IL-4 levels and metabolic parameters that were absent under normal conditions. Thus, intrauterine stress leads to reorganization of the relationships between the parameters of metabolic and immune processes, which are essential for the purposeful behavior of mammals. The effects of stress seem to depend on the sex of the offspring and stage of postnatal development.

Study of Histological Changes of Testis in Rats of Different Ages When Exposed to Frequency 10GHZ Within The X-Band Microwave

This study investigates the impact of 10 GHz microwave exposure, within the X-band range, on rat testicular tissue and sperm development across different age groups. Laboratory rats were divided into a control group of six, which was not exposed to microwaves, and a treatment group of 18, further split into three age-based subgroups (8–12 weeks, 12–16 weeks, and 16–20 weeks), each containing six rats exposed to 10 GHz microwaves for 2.5 hours daily over five weeks. The findings revealed no histological changes in the control group. However, in the treated groups, significant alterations were observed: the youngest group showed a lack of sperm formation and loss of spermatocytes; the middle group displayed malformed sperm and reduced numbers; and the oldest group experienced a decrease in sperm count and minor shape alterations. Additionally, after five weeks, all treated groups exhibited damage to the testicular interstitial tissue, including ruptures and space formation between seminiferous tubules. This study suggests potential risks of microwave exposure on reproductive health and lays the groundwork for future research in this area.

Development of a chronic compression spinal cord injury model in neonatal and adult rats.

Spinal cord injury presents a significant burden globally, with traumatic spinal cord injury being the predominant cause historically. However, nontraumatic spinal cord injury (NTSCI) is emerging as a significant contributor, particularly in developed nations, yet it remains poorly understood due to underreporting and misclassification. NTSCI, spanning various etiologies such as bony growths, vascular conditions, infections, neoplastic conditions, and immune disorders, poses unique challenges in diagnosis and treatment, often resulting in lifelong morbidity. This study addresses the lack of suitable animal models for NTSCI research, especially in neonatal animals. Utilizing a solid spacer approach, we developed a compression NTSCI model applicable to both neonatal and adult Sprague-Dawley rats. Through anatomical measurements and invivo experiments, we confirmed the feasibility and safety of the spacer insertion procedure and observed no acute off-target effects. The versatility of this model lies in its adaptability to different ages of rats, offering a cost-effective and reproducible means to induce graded injuries. Moreover, behavioral assessments demonstrated observable hindlimb function, validating the model's utility for studying functional outcomes. Although challenges persist, particularly in accounting for spinal column growth in neonatal animals, this model fills a crucial gap in pediatric NTSCI research. By providing a platform to investigate pathophysiological mechanisms and test potential treatments, it offers promising avenues for advancing our understanding and management of pediatric NTSCI.

Effects of Aging on New Bone Regeneration in a Mandibular Bone Defect in a Rat Model.

The effects of aging on the healing capacity of maxillofacial bone defects have not been studied. The aim of this study was to evaluate the effects of aging on the regeneration of round bony defects in the mandible. We created a round-shaped bony defect in the mandibular angle area in rats of different ages (2-[2 M], 10-[10 M], and 20-month-old [20 M]) and evaluated new bone regeneration in these groups. Changes in bone turnover markers such as alkaline phosphatase, procollagen type I N-terminal propeptide (PINP), cross-linked C-telopeptide of type I collagen, and tartrate-resistant acid phosphatase 5B (TRAP5b) were investigated. The bone volume/total volume and bone mineral density of the 20 M group were significantly higher than those of the 2 M group (p = 0.029, 0.019). A low level of the bone formation marker PINP was observed in the 20 M group, and a high level of the bone resorption marker TRAP5b was observed in the 10 M and 20 M groups. Micro-computed tomography (µ-CT) results showed that older rats had significantly higher bone formation than younger rats, with lower serum levels of PINP and higher levels of TRAP5b. The local environment of the old rat bone defects, surrounded by thickened bone, may have affected the results of our study. In conclusion, old rats showed greater new bone regeneration and healing capacity for round mandibular bone defects. This result was related to the fact that the bone defects in the 20 M rat group provided more favorable conditions for new bone regeneration.

The effect of hypochlorous acid inhalation on the activity of antioxidant system enzymes in rats of different ages

Hypochlorous acid HOCl is an effective disinfectant with a broad spectrum and high rate of microbicidal action. Its use for air treatment can be an effective tool for the prevention and therapy of infectious diseases. In this work, the in vivo study was conducted on 110 Wistar Han rats (12 and 72 weeks old) on the effect of a single inhalation of air containing gaseous HOCl on the activity of antioxidant system enzymes. For this, a special installation was designed to uniformly maintain the concentration of HOCl in the air and regulate it over a wide range. Inhalation exposure was carried out for 4 h at total chlorine concentrations in the air of approximately 2.0 mg/m3 and 5.0 mg/m3, after which the animals were observed for 14 days. The effect of inhalation on the antioxidant system activity varied significantly in animals of different ages. Catalase activity in young rats increased approximately 2-fold on days 1-2 after inhalation, regardless of the HOCl concentration, while in old animals a sharp dose-dependent decrease was initially observed. The glutathione peroxidase activity in animals of both ages increased upon inhalation of air with 5.0 mg/m3 HOCl, and in old animals this was more pronounced; when the HOCl concentration decreased to 2.0 mg/m3, this indicator increased slightly in old rats and remained virtually unchanged in young ones. The glutathione reductase activity when exposed to 2.0 mg/m3 HOCl did not change for both age groups, and with increasing HOCl concentration it increased by 1.5-2.0 times in all animals.

A Comparative Study of the Temperature Coefficient Q10 in Hibernating Ground Squirrels Urocitellus undulatus and Cooled Rats of Different Ages

A Comparative Study of the Temperature Coefficient Q10 in Hibernating Ground Squirrels Urocitellus undulatus and Cooled Rats of Different Ages

Role of BKCa channels in pial vessel dilation in rats of different ages

Role of BKCa channels in pial vessel dilation in rats of different ages

The effect of exposure to RF-EMF from the laboratory simulator of 5G NR base station on physiological parameters and cognitive abilities of male wistar rats of different ages

In this article, the impact of radiofrequency electromagnetic field (RF-EMF) exposure from a simulated base station for the 5G New Radio (5G NR) telecommunication on rats was studied. The base station affects all age groups of the population, thus, for the first time, the experiment was conducted on male Wistar rats of three different ages (juvenile, adult, and presenile). The base station exposure parameters were chosen according to ICNIRP recommendations for limiting the exposure to radiofrequency electromagnetic field: frequency 2.4 GHz with an average specific absorption rate of 0.0076 W/kg and 0.0059 W/kg over the whole body of experimental animals. Throughout the experiment, body weight was examined weekly, and the dynamics of body weight gain was monitored. Rectal and skin surface temperature on the right hind limb was monitored weekly. Testing in the Morris water maze was performed during the last, Week 5, of RF-EMF exposure. After euthanasia, organ weights were determined in experimental and control animals. None of the investigated parameters did show any statistically significant differences between exposed and control animals of the same age. The data obtained can be used to assess the possible consequences of chronic exposure to RF-EMF from 5G NR base stations.

The Energy Required to Synthesize Lean and Adipose Tissue in Rats.

Although the energy stored in lean tissue (LT) and adipose tissue (AT) is well known, the energy required to synthesize these tissues is less clear. While elucidating the energy required for AT synthesis may not be so important, the elucidation of the energy required for LT synthesis is important for individuals who aim to increase their skeletal muscle. Theoretically the energy at the point at which ΔLT/Δbody weight (BW) reaches 100% on a regression curve, which indicates the relationship between ΔLT/ΔBW and the energy used to accumulate body tissue, is considered to be the energy expended to synthesize LT. We therefore investigated the relationship using rats. Rats of different ages, and rats in exercised or sedentary states were used because their ΔLT/ΔBW was expected to be different. ΔLT/ΔBW was higher in the 4-wk-old group than in the 8-wk-old group and higher in the exercise group than in the sedentary group. We found a positive correlation between ΔLT/ΔBW and the energy expended to synthesize tissues that accumulated in the body. This energy was lower in the 8-wk-old group, which had a lower ΔLT/ΔBW in comparison to the 4-wk-old group, but was not affected by exercise. The regression curve revealed that the energy expended to synthesize LT was 2.9 kcal/g, while that expended to synthesize AT was 1.1 kcal/g. Therefore, combined with the energy accumulated to the tissues, the energy required to accumulate LT is approximately 4.0 kcal/g, while that required to accumulate AT is approximately 8.5 kcal/g.

Diet-induced and age-related changes in rats: the impact of N-stearoylethanolamine intake on plasma lipoproteins, adiponectin, and adipocyte cholesterol-phospholipid composition

Adiponectin is secreted by adipose tissue, associated with lipoprotein (LP) metabolism, down-regulated­ in insulin resistance states, and reduced in individuals suffering from obesity and cardiovascular diseases. Phospholipids and cholesterol are the main components of cell membranes and play a critical role in storage and secretory adipocyte functions. N-stearoylethanolamine (NSE) is a minor lipid affecting cell membrane lipids’ composition. Our study aimed to investigate plasma levels of adiponectin and cholesterol of low- and high-density LP (LDL and HDL) and adipocyte cholesterol-phospholipid (Chol-PL) composition of different age rats with high-fat diet (HFD)-induced obesity and insulin resistance and their changes under NSE administration. Our study demonstrated that chronic dietary fat overloading leads to obesity accompanied by impairment of glucose tolerance, a manifestation of dyslipidemia, and changes in plasma adiponectin levels in rats from two age groups (10-month-old and and 24-month-old). Prolonged HFD led to a reduction in plasma adiponectin levels and the growth of adipocyte cholesterol content in rats of different ages. A significant increase in plasma LDL-Chol level and main adipocyte PLs (phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and lysophosphatidylcholine) was observed in younger rats, whereas not detected in elder animals after dietary fats overloading. The decrease in the content of anionic phospholipids (phosphatidylinositol + phosphatidylserine) was also detected in 10-month-old HFD rats compared to the control animals. NSE administration positively affected the normalization of adiponectin levels in both age HFD groups. It significantly impacted the reduction of LDL-Chol levels and the growth of HDL-Chol concentration in the blood plasma of 10-month-old rats as well as PL-composition of young HFD rats and anionic PL restoring in 24-month-old rats. The positive effect on investigated parameters makes NSE a prospective agent for treating diet-induced and age-related metabolic disorders threatening cardiovascular diseases. Keywords: adiponectin, adipose tissue, aging, cholesterol, dyslipidemia, lipoproteins, N-stearoylethanolamine, phospholipids

Investigating the Effect of Resistance-Aerobic Training on the Absorption and Resorption Biomarkers of Bone Tissue in Young, Adult and Elderly Male Rats

Introduction: Exercise training is likely to be a non-pharmacological intervention to improve bone health in children and the elderly. The aim of this study was to investigate the effect of resistance-aerobic training on RUX2, CTX, RANKL and ALP biomarkers in rats of different ages. Methods: In the present experimental study, 30 male Wistar rats were obtained from Instituto Pasteur of Iran and were divided into three groups according to their age: immature (2 weeks old), mature (6 weeks old) and elderly (96 weeks old). In each age group, the mice were randomly divided into two training (n=5) and control (n=5) groups. Six weeks of combined training included three sessions of aerobic training and three sessions of resistance training per week. Extracting genes by PCR method was used. One-way analysis of variance and Tukey's post hoc test and SPSS16 software were used. The significance level P≥0.05 was considered. Results: One-way analysis of variance showed that resistance-aerobic training has had a significant effect on RUNX2, RANKL and ALP variables of rats in different age groups (P < 0.05). This significance was not observed in CTX variable (P > 0.05). On the other hand, the results of Tukey's RUNX2 test were significantly different between the adult training and elderly training groups (p=‌0.019) as well as between the elderly control groups (p = 0.01) and adult training (p = 0.002). Regarding the RANKL variable, it showed that there was a significant difference only between the adult exercise group and the elderly control group (p = 0.01). Conclusion: Resistance-endurance training probably increases absorption and reabsorption biomarkers such as RUX2, RANKL and ALP in immature, mature and elderly male rats.

Sex, age, and species differences of perfluorooctanoic acid modeled by flow- versus permeability-limited physiologically-based pharmacokinetic models

This study aimed to investigate sex, age, and species differences of perfluorooctanoic acid (PFOA) using physiologically-based pharmacokinetic (PBPK) models in rats and humans. PBPK models were generally developed as either flow- or permeability-limited models. The flow-limited model is cost-effective and allows for human PK prediction through simple allometric scaling, while the permeability-limited model can incorporate detailed information on the disposition process through in vitro-in vivo extrapolation (IVIVE). PFOA was administered via oral or intravenous administration with 5 mg/kg in male and female rats of different ages and the data was used to develop the PBPK models. Our results showed that both models successfully captured sex differences in rats, while only the flow-limited model with male rats and the permeability-limited model with both male and female rats provided comparable predictions in the human clinical study. More than the flow-limited model, the permeability-limited model effectively explained sex differences in rats and species differences through IVIVE. Additionally, the ontogeny-based mechanistic description of PFOA disposition enabled the interpretation of age- and sex-dependent pharmacokinetics. Although the flow-limited PBPK model lacked mechanistic interpretability compared to the permeability-limited model, it demonstrated reliable human prediction through simple allometric scaling. In conclusion, the permeability PBPK model could interpret age, sex, and species differences and it could improve the accuracy of human prediction.

Sex and age affect depot expression of Ca2+ channels in rat white fat adipocytes.

White adipose tissue (WAT) requires extracellular Ca2+ influx for lipolysis, differentiation, and expansion. This partly occurs via plasma membrane Ca2+ voltage-dependent channels (CaVs). However, WFA exists in different depots whose function varies with age, sex, and location. To explore whether their CaV expression profiles also differ we used RNAseq and qPCR on gonadal, mesenteric, retroperitoneal, and inguinal subcutaneous fat depots from rats of different ages and sex. CaV expression was found dependent on age, sex, and WFA location. In the gonadal depots of both sexes a significantly lower expression of CaV1.2 and CaV1.3 was seen for adults compared to pre-pubescent juveniles. A lower level of expression was also seen for CaV3.1 in adult male but not female gonadal WFA, the latter of whose expression remained unchanged with age. Relatively little expression of CaV3.2 and 3.2 was observed. In post-pubescent inguinal subcutaneous fat, where the third and fourth mammary glands are located, CaV3.1 was decreased in males but increased in females - thus suggesting that this channel is associated with mammogenesis; however, no difference in intracellular Ca2+ levels or adipocyte size were noted. For all adult depots, CaV3.1 expression was larger in females than males - a difference not seen in pre-pubescent rats. These observations are consistent with the changes of CaV3.1 expression seen in 3T3-L1 cell differentiation and the ability of selective CaV3.1 antagonists to inhibit adipogensis. Our results show that changes in CaV expression patterns occur in fat depots related to sexual dimorphism: reproductive tracts and mammogenesis.

Superoxide dismutase and catalase activity in the blood and liver of rats of different age groups with experimental type 2 diabetes mellitus and skeletal muscle injury

According to 2022 statistics from the Federal State Budgetary Institution National Medical Research Center for Endocrinology, the incidence of type 2 diabetes mellitus in Russia is 92.4% (4.49 million) of patients, and every tenth inhabitant of the Earth already suffers from diabetes mellitus.Purpose of the study: to analyze the dynamics of superoxide dismutase and catalase activity at the systemic and local levels in rats of different ages when modeling type 2 diabetes followed by mechanical injury to skeletal muscle.Object and methods. The study was conducted on white outbred healthy male rats 24 months old (120 individuals) and 6 months old (120 individuals). All old and young animals were divided into four subgroups within their group, 30 animals in each. Animals of the first subgroup in groups of old and young rats are intact rats. Animals of the second subgroup of the group in each group had a mechanical dissection in the area of the middle third of the gastrocnemius muscle of the hind limb. Animals of the third and fourth subgroups of each group were subjected to modeling type 2 diabetes mellitus.After the specified time, the animals of the fourth subgroup of both groups were injured in the middle third of the gastrocnemius muscle of the hind limb.Conclusions. Mechanical injury to the gastrocnemius muscle in combination with type 2 diabetes mellitus is characterized by an intensification of lipid peroxidation and leads to an increase in superoxide dismutase activity in the liver tissue and blood serum of rats, and in young animals the increase in superoxide dismutase activity is more intense than in old ones.

Changes in Blood Leukocyte Composition in Rats of Different Ages after Long-term Cold Adaptation

Changes in Blood Leukocyte Composition in Rats of Different Ages after Long-term Cold Adaptation

Role of BKCa Channels in Pial-Vessel Dilation in Rats of Different Ages

Role of BKCa Channels in Pial-Vessel Dilation in Rats of Different Ages

Serum biochemical indicators in rats of different ages after replacing femoral metaphysis defects with allogeneic bone implants saturated with mesenchymal stem cells

The aim of the study: to evaluate the course of metabolic processes after replacing femoral metaphysis defects with allogeneic bone implants saturated with allogeneic mesenchymal stem cells (MSCs) based on the analysis of serum biochemical indicators of connective tissue metabolism in laboratory rats. Material and methods. A critical-sized transcortical femoral defect model in the femur metaphysis of white rats was used. Blood serum concentrations of glycoproteins, total chondroitin sulfates, total protein and calcium, alkaline and acid phosphatase activity were measured. Results. On the 28th day, in 3-month-old animals with MSC, in comparison with the data of rats without MSC, clear signs of connective tissue formation and bone resorption activity were observed, as evidenced by an increase in serum chondroitin sulfates and acid phosphatase activity. On the 90th day, this group of rats under the influence of MSCs showed signs of decreased bone tissue formation with lower serum activity of alkaline phosphatase. In 3-month-old rats with MSC, signs of the inflammatory process chronization with higher serum concentrations of glycoproteins were detected on the 90th day of the experiment in comparison with data from animals without MSC. In 12-month-old rats with MSCs, signs of bone resorption were documented on the 14th day, which were manifested by a higher serum activity of acid phosphatase with less formation of connective tissue and lower concentrations of chondroitin sulfates. On the 28th day, the effect of MSCs in 12-month-old animals was manifested in the form of a slowdown in bone formation with a decrease in alkaline phosphatase activity. On the 90th day, the connective tissue formation was activated with higher concentrations of chondroitin sulfates in these animals. Conclusions. The studied biochemical indicators in 3-month-old animals showed greater lability. The regeneration phases were faster in 3-month-old animals as well as in animals with alloimplants without MSCs. Injections of allogeneic MSCs together with an allograft immediately after a bone damage, regardless of age, caused signs of bone formation slowing and excessive formation of connective tissue, therefore, the combination of allogeneic MSCs with an allogeneic bone implant is not advisable to use in fresh fractures.

H<sub>2</sub>S-Mediated Dilation of Pial Arteries in Rats of Different Ages: Contribution of K<sub>ATP </sub>and BK<sub>Ca</sub>-Channels

Reactions of pial arteries to exogenous hydrogen sulfide exposure and assessment of the contribution of KATP and BKCa-channels to H2S-mediated dilation was studied in rats of different ages. Intravital microphotography in Sprague-Dawley rats aged 4 and 18 months was used to study the reactions of pial arteries of various diameters to the exposure of exogenous hydrogen sulfide donor solution – sodium hydrosulfide (NaHS, 30 μM), as well as their change with the preliminary use of potassium channel blockers: KATP (glibenclamide, 10 μM) and BKCa (tetraethyl ammonium, 2 mM). It was found that inhibition of H2S-mediated dilation of pial arteries and increase in constrictor responses to exogenous hydrogen sulfide exposure are taking place in rats with age. Age-related changes in H2S-induced dilatory response of the pial arteries in rats depend on the size of the vessels. With age, there is a decrease in the number of dilations of pial arteries with a diameter of more than 20 μm. At the same time, aging does not affect the dilatation of smaller arteries. These disorders are probably associated with changes in the processes caused by the activation of potassium channels. It was found that aging is accompanied by the increasing of KATP-channels contribution to the implementation of H2S-mediated dilation in pial arteries with diameters less than 40 μm. BKCa-channels contribution to the dilatation decreases with age. In 18 months, rats, these channels barely participate in H2S-mediated dilation in arteries with diameters more than 20 μm.

Morphometric assessment of age-related structural changes in the vessels of the microcirculatory bed of the prostate gland under conditions of ethanol intoxication

Vessels of the microcirculatory bed ensure the full trophism of the body at the level of capillary-tissue relations and are the first to respond to various functional and pathological conditions of organs. At the same time, morphological changes in prostate microvasculature with age under conditions of prolonged ethanol poisoning have been understudied. The purpose of this study was to determine the age-related remodelling of the prostate vessels of the microcirculatory bed in case of prolonged alcohol intoxication. Injection, histological, morphometric, and statistical methods were used. The microvasculature of the prostate gland of 80 sexually mature white male rats of different ages was studied, 40 animals served as controls, and 40 rats were injected daily for 28 days with a 30% ethanol solution at a dose of 20 ml/kg intragastrically. Morphometric analysis indicated that chronic ethanol poisoning in white rats significantly reduces the lumens of arterial microvessels and hemocapillaries, while expanding the venous vessels in the microcirculatory bed of the prostate gland. When venous congestion occurs, the density of microvessels decreases, and microcirculation bed is disturbed. This disruption is accompanied by atrophic, dystrophic, and necrobiotic changes in endotheliocytes, epithelial cells, muscle cells, stromal structures, infiltration, and sclerosing. Intragastric 28-day administration of a 30% ethanol solution at a dose of 20 ml/kg to laboratory mature white male rats leads to pronounced structural changes in the microvasculature of the prostate microcirculatory bed: constriction of arterioles, precapillary arterioles and hemocapillaries, dilation of the capillary venules and venules, which is complicated by significant venous haemorrhage, development of atrophy, dystrophy, necrosis of vascular endothelial cells, glandular epithelial cells, muscle cells, connective tissue structures, cellular infiltration, and sclerosis. Vessels of the microcirculatory bed play a leading role in ethanol-induced damage of prostate structures, which dominate in 24-month-old experimental animals

Expression changes of NaV channel subunits correlate with developmental maturation of electrophysiological characteristics of rat cerebellar Purkinje neurons

To investigate the variations in the expression of voltage-gated sodium (Nav) channel subunits during development of rat cerebellar Purkinje neurons and their correlation with maturation of electrophysiological characteristics of the neurons. We observed the changes in the expression levels of NaV1.1, 1.2, 1.3 and 1.6 during the development of Purkinje neurons using immunohistochemistry in neonatal (5-7 days after birth), juvenile (12-14 days), adolescent (21-24 days), and adult (42-60 days) SD rats. Using whole-cell patch-clamp technique, we recorded the spontaneous electrical activity of the neurons in ex vivo brain slices of rats of different ages to analyze the changes of electrophysiological characteristics of these neurons during development. The expression of NaV subunits in rat cerebellar Purkinje neurons showed significant variations during development. NaV1.1 subunit was highly expressed throughout the developmental stages and increased progressively with age (P < 0.05). NaV1.2 expression was not detected in the neurons in any of the developmental stages (P > 0.05). The expression level of NaV1.3 decreased with development and became undetectable after adolescence (P < 0.05). NaV1.6 expression was not detected during infancy, but increased with further development (P < 0.05). NaV1.1 and NaV1.3 were mainly expressed in the early stages of development. With the maturation of the rats, NaV1.3 expression disappeared and NaV1.6 expression increased in the neurons. NaV1.1 and NaV1.6 were mainly expressed after adolescence. The total NaV protein level increased gradually with development (P < 0.05) and tended to stabilize after adolescence. The spontaneous frequency and excitability of the Purkinje neurons increased gradually with development and reached the mature levels in adolescence. The developmental expression of NaV subunits was positively correlated with discharge frequency (r=0.9942, P < 0.05) and negatively correlated with the excitatory threshold of the neurons (r=0.9891, P < 0.05). The changes in the expression levels of NaV subunits are correlated with the maturation of high frequency electrophysiological properties of the neurons, suggesting thatmature NaV subunit expressions is the basis of maturation of electrophysiological characteristics of the neurons.