Ontogenesis In Rats Research Articles

Time course of glycine receptor GlyRα3 expression in the Bötzinger complex during early postnatal ontogenesis in rats

Time course of glycine receptor GlyRα3 expression in the Bötzinger complex during early postnatal ontogenesis in rats

ИЗМЕНЕНИЯ ТОЛЩИНЫ МИЕЛИНОВОЙ ОБОЛОЧКИ И СТРУКТУРА МЕЖУЗЛОВЫХ СЕГМЕНТОВ МИЕЛИНОВЫХ НЕРВНЫХ ВОЛОКОН СЕДАЛИЩНОГО НЕРВА КРЫСЫ В ОНТОГЕНЕЗЕ

ИЗМЕНЕНИЯ ТОЛЩИНЫ МИЕЛИНОВОЙ ОБОЛОЧКИ И СТРУКТУРА МЕЖУЗЛОВЫХ СЕГМЕНТОВ МИЕЛИНОВЫХ НЕРВНЫХ ВОЛОКОН СЕДАЛИЩНОГО НЕРВА КРЫСЫ В ОНТОГЕНЕЗЕ

Plasticity of Central and Peripheral Sources of Noradrenaline in Rats during Ontogenesis.

The morphogenesis of individual organs and the whole organism occurs under the control of intercellular chemical signals mainly during the perinatal period of ontogenesis in rodents. In this study, we tested our hypothesis that the biologically active concentration of noradrenaline (NA) in blood in perinatal ontogenesis of rats is maintained due to humoral interaction between its central and peripheral sources based on their plasticity. As one of the mechanisms of plasticity, we examined changes in the secretory activity (spontaneous and stimulated release of NA) of NA-producing organs under deficiency of its synthesis in the brain. The destruction of NA-ergic neurons was provoked by administration of a hybrid molecular complex- antibodies against dopamine-β-hydroxylase associated with the cytotoxin saporin- into the lateral cerebral ventricles of neonatal rats. We found that 72 h after the inhibition of NA synthesis in the brain, its spontaneous release from hypothalamus increased, which was most likely due to a compensatory increase of NA secretion from surviving neurons and can be considered as one of the mechanisms of neuroplasticity aimed at the maintenance of its physiological concentration in peripheral blood. Noradrenaline secretion from peripheral sources (adrenal glands and the organ of Zuckerkandl) also showed a compensatory increase in this model. Thus, during the critical period of morphogenesis, the brain is integrated into the system of NA-producing organs and participates in their reciprocal humoral regulation as manifested in compensatory enhancement of NA secretion in each of the studied sources of NA under specific inhibition of NA production in the brain.

Molecular mechanisms of synthesis of noradrenaline as an inducer of development in the adrenal glands of rats in ontogenesis.

The level of gene expression and the protein content of tyrosine hydroxylase and dopamine β-hydroxylase were determined. In the perinatal period of rats, when noradrenaline functions as a morphogenetic factor, the level of gene expression of these enzymes increased and the content of protein products of these genes was almost unchanged, indicating the difference in the regulatory mechanisms of their transcription and translation.

On the influence of prenatal hypoxia on formation of the orexinergic system and sleep–wake cycle in early ontogenesis of rats

The role of orexin in the organization of the sleep–wake cycle (SWC) is well known. The aim of this study was to examine the timing of the orexinergic system formation in rat postnatal ontogenesis and to assess the role of orexin A in the SWC organization under normal conditions and after prenatal hypoxia undergone on days 14 and 19 of embryogenesis. The SWC was investigated in 30-day-old rats with electrodes implanted into the somatosensory and occipital cortex. Immunoreactivity within the orexigenic structures of the lateral hypothalamus was analyzed. It was shown that in control 14-day-old animals the orexinergic structures were in their formative stage, whereas in 30-day-old rats they were already as formed as in adults. In 14-day-old rats, prenatal hypoxia evoked retarded formation of the orexinergic system. In 30-day-old animals, hypoxia undergone in the prenatal period increased the activity of the orexinergic system, which was higher in animals exposed to hypoxia on day 19 than on day 14 of gestation. In 30-day-old rats, these changes were reflected in the SWC formation in the form of shorter slow-wave sleep, more fitful sleep and increased number of transitions from slow- to fast-wave sleep. The results obtained are discussed in the light of the adaptive-compensatory role of the orexigenic system in postnatal ontogenesis after prenatal damage to the central nervous system.

Regulation of caspase-3 content and activity in rat cortex in norm and after prenatal hypoxia

The analysis of caspase-3 activity, content and regulation in the brain cortex during the first month of postnatal ontogenesis in rats with normal development and after prenatal normobaric hypoxia on ?14 (3 h, 7% O2) has been performed. Prenatal hypoxia compared to controls was found to result in a statistically significant increase in the content (3.6-fold) and activity (5.3-fold) of caspase-3 in the neocortex of rats in the period of the most intensive synaptogenesis and cell elimination (P20–P35). A single intraventricular injection on ?20 of a caspase inhibitor Ac-DEVD-CHO altered the activity and content of this enzyme although the dynamics of the changes was different in rats with normal and pathological embryogenesis. In the first hours after inhibitor administration a decrease in caspase-3 activity was observed in both groups of animals. Later, on days 1–5 after injection, there was further decrease of caspase-3 activity (3.9-fold) in rats subjected to prenatal hypoxia although the enzyme content was not significantly different from the age-matched controls. On the contrary, in rats with normal embryogenesis on days 1–5 after the injection there was a significant (two-fold) increase in the content of active caspase-3 form and its enzyme activity (2.5-fold) although these characteristics returned down to the control values on the 15th day after inhibitor administration. After administration of Ac-DEVD-CHO to adult rats (P90) with normal development there was also caspase-3 inhibition 3 h after the injection, however no further increase in its activity on days 1–5 after injection, similar to those observed in young animals, has been found. The data obtained testify to the difference in the agerelated dynamics and regulation of the active form of caspase-3 in the period of the most intensive brain development of rats with normal embryogenesis and subjected to prenatal hypoxia.

Prenatal Hypoxia in Different Periods of Embryogenesis Differentially Affects Cell Migration, Neuronal Plasticity, and Rat Behavior in Postnatal Ontogenesis.

Long-term effects of prenatal hypoxia on embryonic days E14 or E18 on the number, type and localization of cortical neurons, density of labile synaptopodin-positive dendritic spines, and parietal cortex-dependent behavioral tasks were examined in the postnatal ontogenesis of rats. An injection of 5′ethynyl-2′deoxyuridine to pregnant rats was used to label neurons generated on E14 or E18 in the fetuses. In control rat pups a majority of cells labeled on E14 were localized in the lower cortical layers V-VI while the cells labeled on E18 were mainly found in the superficial cortical layers II-III. It was shown that hypoxia both on E14 and E18 results in disruption of neuroblast generation and migration but affects different cell populations. In rat pups subjected to hypoxia on E14, the total number of labeled cells in the parietal cortex was decreased while the number of labeled neurons scattered within the superficial cortical layers was increased. In rat pups subjected to hypoxia on E18, the total number of labeled cells in the parietal cortex was also decreased but the number of scattered labeled neurons was higher in the lower cortical layers. It can be suggested that prenatal hypoxia both on E14 and E18 causes a disruption in neuroblast migration but with a different outcome. Only in rats subjected to hypoxia on E14 did we observe a reduction in the total number of pyramidal cortical neurons and the density of labile synaptopodin-positive dendritic spines in the molecular cortical layer during the first month after birth which affected development of the cortical functions. As a result, rats subjected to hypoxia on E14, but not on E18, had impaired development of the whisker-placing reaction and reduced ability to learn reaching by a forepaw. The data obtained suggest that hypoxia on E14 in the period of generation of the cells, which later differentiate into the pyramidal cortical neurons of the V-VI layers and form cortical minicolumns, affects formation of cortical cytoarchitecture, neuronal plasticity and behavior in postnatal ontogenesis which testify to cortical dysfunction. Hypoxia on E18 does not significantly affect cortical structure and parietal cortex-dependent behavioral tasks.

Secretory activity of the brain and peripheral organs: Spontaneous and stimulated release of noradrenaline in the ontogenesis of rats.

Spontaneous and K(+)-stimulated release of noradrenaline from the hypothalamus, adrenal gland, and organ of Zuckerkandl under their flowing incubation was investigated in the perinatal period of ontogenesis of rats. The results suggest that, during the investigated period of ontogenesis, adrenal glands are the main source of noradrenaline in the blood, whereas the contributions of the organ of Zuckerkandl and the brain are not as significant and change during this period.

ОСОБЕННОСТИ СВОБОДНОРАДИКАЛЬНЫХ ПРОЦЕССОВ ПРИ ИММОБИЛИЗАЦИОННОМ СТРЕССЕ У КРЫС В ОНТОГЕНЕЗЕ

ОСОБЕННОСТИ СВОБОДНОРАДИКАЛЬНЫХ ПРОЦЕССОВ ПРИ ИММОБИЛИЗАЦИОННОМ СТРЕССЕ У КРЫС В ОНТОГЕНЕЗЕ

Signal molecules during the organism development: Central and peripheral sources of noradrenaline in rat ontogenesis.

Using the method of high performance liquid chromatography with electrochemical detection, the age dynamics of the content of noradrenaline (NA) in the brain, adrenal gland, and the organ of Zuckerkandl in prenatal (18th and 21st days of embryogenesis) and early postnatal (3, 7, 15, and 30th days) periods of development was studied. The potential contribution of these organs to the formation of physiologically active concentration of noradrenalin in the blood was also assessed. The results suggest that, during the development of the organism, the activity of the sources of noradrenaline in the general circulation changes, which gives a reason to assume the existence of humoral interaction between NA-producing organs in the perinatal period of ontogenesis.

The secretion of noradrenaline from the brain into the peripheral blood during rat ontogenesis

We studied the endocrine function of the noradrenergic system in the developing brain. The data on the age-related dynamics of the noradrenaline concentration in plasma and in the hypothalamus and mesencephalon–rhombencephalon before and after the formation of the blood–brain barrier indirectly indicates the possibility of noradrenaline secretion from the brain to the peripheral blood. The direct evidence that the rat brain may be a source of noradrenaline in the peripheral blood before the formation of the blood–brain barrier was first obtained using a model of chronic specific inhibition of noradrenaline synthesis in the neonatal rat brain. It suggests that the brain is involved in the regulation of the development and functioning of peripheral target organs during this period.

Correlation and spectral analysis of vascular tone regulator mechanisms in paired formations during postnatal ontogenesis in rats.

The study focused on the changes of microcirculation indices and components of the vascular tone of endothelial, neural, and myogenic nature in symmetrical skin sites of temples, forehead, auricles, scapulae, and groin during postnatal ontogeny. Initially, microcirculation indices in the symmetrical regions decreased to postnatal day 10, thereafter they surpassed the initial level at the age of 30 days. The endothelial, neural, and myogenic indices of vascular tone changed differently in the symmetrical left and right sites. On the right side, all indices increased by the postnatal day 21 ("redundancy" phase), and by postnatal day 30 surpassed the initial level by two times. On the left side, the redundancy phase manifested in the endothelial component on postnatal day 10, but to postnatal day 30 all three indices dropped below the initial level.

Changes of mitochondria in the contractile cardiomyocytes during postnatal rat ontogenesis.

Background. CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause. An estimated 17.5 million people died from CVDs in 2012, representing 31% of all global deaths. Of these deaths, an estimated 7.4 million were due to coronary heart disease and 6.7 million were due to stroke. Over three quarters of CVD deaths take place in low- and middle-income countries. Objective. Ultrastructural analysis of mitochondria in the rat contractile cardiomyocytes during postnatal ontogenesis. Methods. As the object of the study were used neonatal rat hearts, on the 5th, 10th, 15th, 30th days of life and mature animals. Hearts were investigated by the transmission electron microscopy. Volume density and numerical density of mitochondria were estimated. The Paired Student’s t-test was applied. Results. Was conducted a comprehensive ultrastructural analysis of mitochondria contractile cardiomyocytes, which allowed us to determine changes in the qualitative and quantitative parameters of mitochondria during postnatal ontogenesis, and helps to explain the dynamics and the development of mitochondria heart muscles cells after birth. Conclusion. It was shown that from the 1st to the 5th day there was a significant increase in volume density of mitochondria, which was accompanied by the increasing complexity of the ultrastructural organization of organelles. Following 20th day of postnatal ontogenesis mitochondrial structure was approaching the definitive condition and on the 30th day was the same as the mature myocardium.

Brain as an endocrine source of circulating 5-hydroxytryptamine in ontogenesis in rats

This study was aimed to test the authors’ hypothesis stating that the developing brain before the closure of the blood brain barrier (BBB) operates as an endocrine organ that secretes classical neurotransmitters and neuropeptides into the general circulation. 5-Hydroxytryptamine (5-HT) was selected as a marker of brain endocrine activity though it is also secreted by peripheral organs. 5-HT was detected in blood of rats in a biologically active concentration at any studied age, from the 21st embryonic day till the 30th postnatal day. The brain was proven to be a source of circulating 5-HT before the BBB closure by showing that the 5-HT concentration in blood decreased significantly after the inhibition of 5-HT synthesis in the brain of neonates. The 5-HT concentration in blood was not diminished after the BBB closure, apparently due to compensatory increase of 5-HT secretion by peripheral sources. Thus, brain-derived 5-HT is delivered to the general circulation before the BBB closure being potentially capable of providing endocrine regulation of target organs.

Catecholaminergic regulation of autorhythmical viscero- and somatomotor activity in early rat ontogenesis

Ontogenetic peculiarities of catecholaminergic regulation of three vitally important physiological processes are described: heart beating, respiration, and early somatomotor activity. They are subordinated to the autorhythmical regime and are submitted to modulating effects ofnoradrenergic and dopaminergic mechanisms. There are considered age-related changes of this effect whose peculiarity are polar changes of reactions in the process of their maturation from the predominantly excitatory at early stages to predominantly inhibitory ones.

Formation of lateralization of manipulatory food-procuring behavior in the white rat early ontogenesis

Study of peculiarities of formation of preference in use of one of forelegs at learning of the manipulatory food-procuring skill has been carried out at different stages of early ontogenesis of white rats. It was established that as early as at the 3-week age the rat pups were already able to learn getting food from a narrow test-tube; however, no expressed preference in using one of the extremities was revealed. After repeated testing of adult rats at the age of 4 months the number of ambidexters was significantly higher than in the control animal group. At learning of the 30-day old rat pups of this manipulatory skill, in the majority of the rat pups, no significant lateralization also was found in using the foreleg. At repeated testing of adult rats the amount of ambidexters did not differ from that in the control group of animals. The obtained results indicate the existence of critical periods in formation of lateral preference in performance of the manipulatory food-procuring skill. There also was shown effect of learning in early ontogenesis on the capability for lateralization of this skill in the adult state in rats.

Fatty acids of phospholipids of brain cell nuclei in rat ontogenesis

Experiments were carried out on the 19-day old rat embryos, the 5- and 45-day old rat pups, and the 1.4-1.5-year old rats. Phospholipids and their fatty acid composition in brain cell nuclei were studied using methods of extraction, two-dimensional thin-layer chromatography, and spectrofluorimetry. In the course of ontogenesis, the percentage of different classes of nuclear phospholipids was changed; at the postembryonic period, the unsaturation index of lipids (phosphatidylcholine and phosphatidylethanolamine) and the content of unsaturated (especially polyenic) fatty acids decreased. Microviscosity of nuclear membranes increased; this changes were also shown earlier in phylogenesis of vertebrates. Thus, the facts revealed in the present work correspond to the recapitulation law. It is suggested that such change of lipid ratio and of composition of their fatty acids as well as of the membrane microviscosity serve for regulation of functions of membrane proteins and have adaptive character.

PARP-I and p53 expression in Sertoli cell during rat ontogenesis

Poly ADP-ribose polymerase-I (PARP-I), a nuclear I I 3-kDa Zinc-finger protein, catalyze poly ADP-ribosilation reactions and is involved in many physiological and pathological conditions such as cell differentation and proliferation, transcriptional events, carcinogenesis and apoptosis. Sertoli cells are essential for reproduction, providing germ cells with nutrients and hormonal signals. Poly ADP-ribosylation has been well studied during sperm cell maturation but the role of such reactions at the Sertoli cell level remains unknown. In the present work we analyzed the expression of PARP-I during the postnatal differentiation of Sertoli cells isolated from rat testis. We compared PART-I expression with that of p53, whose activity is modulated by poly ADP-ribosylation. Quantitative RT-PCR technique was employed. Our data demonstrate for the first time PART-I expression in rat Sertoli cell both in the neonatal and peripubertal period. p53 expression pattern was found opposite to that of PART-I, suggesting that PART-I is possibility in charge for protecting the developing Sertoli cells when the activity of p53 lowers.

Neurotransmitter levels in the hypothalamus during postnatal development of rats.

The content of norepinephrine (NE), epinephrine (E), dopamine (DA) and serotonin (5-HT) in the rat hypothalamus was determined at four hours time interval during 24 hours period at the age of 12, 23, 27 and 75 days. It was found that the content of NE in the hypothalamus is low in 12 day-old rats, and during the postnatal period a gradual increase of NE was noted. The content of E in the hypothalamus is low in 12- to 27-day-old rats and an important increase was found in adult animals. The high values of DA and 5-HT concentration were found in the hypothalamus of 12-day-old rats and a transient decrease of 5-HT and DA at the age of 23 days was noted, further an important increase of the content of both neurotransmitters in the hypothalamus was demonstrated later in life. The presence of circadian rhythm of hypothalamic NE, E, DA and 5-HT content was found in 12-, 23-, 27-day-old and in adult rats overfed or underfed during the suckling period. However, no significant correlation was observed between the NE and E levels in the hypothalamus and the diurnal fluctuations of plasma corticosterone concentrations. In adult animals an inverse correlation between the plasma corticosterone level and hypothalamic 5-HT content was noted. In young 12- and 23-day-old rats the correlation between 5-HT in the hypothalamus and corticosterone in the plasma was positive. These results indicate that the shift of peak in plasma corticosterone levels during postnatal ontogenesis of rats observed in previous experiments is not dependent on the changes in diurnal fluctuation of hypothalamic neurotransmitter concentrations.

Development of central and peripheral serotonin-producing systems in rats in ontogenesis

The work deals with study of development of central and peripheral serotonin-producing systems in rat ontogenesis before and after formation of the blood-brain barrier. By the method of highly efficient liquid chromatography it has been shown that the serotonin level in peripheral blood before formation of the blood-brain barrier (in fetuses and neonatal rats) is sufficiently high for realization of physiological effect on target cells and organs. At the period of formation of the blood-brain barrier the serotonin level in brain sharply rises, whereas the serotonin concentration and amount in plasma and duodenum increase insignificantly. Completion of formation of the blood-brain barrier is accompanied by a significant increase of the serotonin content in duodenum, probably for maintenance of the high serotonin level in blood. To evaluate secretory activity, the mean rate of daily increment of the serotonin in the studied tissues was calculated. In brain, this parameter was maximal at the period of formation of the blood-brain barrier and then sharply fell, whereas in duodenum it rose markedly after completion of the barrier formation. In plasma this parameter decreased statistically significantly at the period of formation of the blood-brain barrier - from the 4th to the 16th postnatal days. This allows thinking that brain before formation of the blood-brain barrier is a most important source of serotonin in peripheral blood.