Early Postnatal Ontogeny Research Articles

Impairments to Conditioned Reflex Activity in Adult Rats after Administration of Interleukin-1β during Early Postnatal Ontogeny

Impairments to cognitive functions in children and adolescents often result from a variety of types of prenatal pathology (birth traumas, ischemia, hypoxia, and allergic and infectious diseases in early life) accompanied by high levels of production of the proinflammatory cytokine interleukin-1β. The studies reported here identified impairments to the acquisition of conditioned active and passive reflex avoidance reactions in adult animals given interleukin-1β during the third week of life.

Neonatal injections of pharmacological agents and their remote genotype-dependent effects in mice and rats

Experimental data were reviewed which demonstrated that the neonatal injection effects of certain biologically active drugs (ACTH(4-10) fragment and its analogue Semax, piracetam, caffeine, levetiracetam, busperone, etc.) could be detected in adult animals as changes in physiological and behavioral reactions and in several morphological traits as well. Audiogenic seizures proneness, anxiety-fear and exploration behavior as well as pain sensitivity were analyzed. The remote effects discovered were either similar in direction to those applied to an adult organism, or opposite to it. Pharmacological treatments of such type presumably interfere the CNS development during early postnatal ontogeny and change the normal pattern ofbrain development. These modulatory influences could be due to changes in neurotransmitter system development and are presumably capable to induce CNS morphological deviations (numbers of neurons, adult neurogenesis).

Formation of humoral immunity in calves in health and disease

It is known that the health and productivity of young animals are determined in many respects by the development of the humoral link of the immune sys� tem most objectively reflecting the effectiveness of the interaction of T and B cells and antigenpresenting cells during the immune response. During postnatal development of animals, a successive change of natu� ral passive humoral protection to active immunity occurs in animals, the level of which, with consider� ation of age and individual characteristics, allows assessing both the degree of resistance of the organism due to lactogenic immunity and subsequently the ade� quacy of the reaction of the immune system to the action of environmental factors. In early postnatal ontogeny, it is impossible to dif� ferentiate maternal isotypes (classes, subclasses) of immunoglobulins or specific antibodies and those produced by own immune system present in new� borns, and the revelation, for example, of allotypic variants is difficult. Therefore, the most accessible is a determination of the level of immunoglobulins in dynamics, which makes it possible with high probabil� ity to judge the formation of humoral immunity in young animals. The purpose of the present investigation was to study humoral immunity in calves with a different level of passive protection in health and disease under con� dition of an industrial complex.

Ultrastructure of Neurons in the Caudal Mesenteric Ganglion in Kittens during Early Postnatal Ontogeny

Electron microscopic studies were performed to study the development of the neural elements of the sympathetic caudal mesenteric ganglion (CMG) in cats from the moment birth to the end of the second month of life. Non-simultaneous maturation of neurons and their terminals was seen; along with completely developed neurons, gliocytes, and synapses, neonatal kittens had numerous immature forms of these structures. In animals aged 14 days, the proportion of immature cells decreased, though neuron destruction was more frequent at this age. The CMG of animals of all age groups contained mostly axodendritic synapses, along with fewer axosomatic synapses. CMG ultrastructure in kittens became comparable with that in adult animals at age 60 days.

Different Cranial Ontogeny in Europeans and Southern Africans

Modern human populations differ in developmental processes and in several phenotypic traits. However, the link between ontogenetic variation and human diversification has not been frequently addressed. Here, we analysed craniofacial ontogenies by means of geometric-morphometrics of Europeans and Southern Africans, according to dental and chronological ages. Results suggest that different adult cranial morphologies between Southern Africans and Europeans arise by a combination of processes that involve traits modified during the prenatal life and others that diverge during early postnatal ontogeny. Main craniofacial changes indicate that Europeans differ from Southern Africans by increasing facial developmental rates and extending the attainment of adult size and shape. Since other studies have suggested that native subsaharan populations attain adulthood earlier than Europeans, it is probable that facial ontogeny is linked with other developmental mechanisms that control the timing of maturation in other variables. Southern Africans appear as retaining young features in adulthood. Facial ontogeny in Europeans produces taller and narrower noses, which seems as an adaptation to colder environments. The lack of these morphological traits in Neanderthals, who lived in cold environments, seems a paradox, but it is probably the consequence of a warm-adapted faces together with precocious maturation. When modern Homo sapiens migrated into Asia and Europe, colder environments might establish pressures that constrained facial growth and development in order to depart from the warm-adapted morphology. Our results provide some answers about how cranial growth and development occur in two human populations and when developmental shifts take place providing a better adaptation to environmental constraints.

Development of regulation of the cardiac chronotropic function in albino rats during the early postnatal ontogeny according to the results of spectral analysis of heart rhythm variability

Regulation of the cardiac chronotropic function was studied by spectral analysis of cardiac rhythm variability in HF, LF, and VLF bands in rats at various stages of the early postnatal ontogeny. The inadequacy of the regulatory mechanisms during the first days of life manifested by low power of all waves (particularly HF) in the cardiac rhythm variability spectrum. On day 14 of life, the cardiointerval variability was formed by HF waves, their low power together with increasing heart rate indicating more intense sympathetic effects. On day 21 of life, a potent elevation of the VLF power reflected a stronger centralization of regulation from higher autonomic centers. The age of 28 days was characterized by a sharp increase of HF activity and could be regarded as the turning point in the development of parasympathetic effects and activity of the autonomic regulation contour. From the age of 35 days, the wave power and the proportion of the spectral components of cardiac rhythm variability in albino rats corresponded to the adult pattern; a trend to the central regulation predominance and to greater rigidity of cardiac rhythm formed only with the onset of sexual maturation.

Shape, variance and integration during craniogenesis: contrasting marsupial and placental mammals

Studies of morphological integration can provide insight into developmental patterns, even in extinct taxa known only from skeletal remains, thus making them an important tool for studies of evolutionary development. However, interpreting patterns of integration and assessing their significance for organismal evolution requires detailed understanding of the developmental interactions that shape integration and how those interactions change through ontogeny. Thus far, relatively little comparative data have been produced for this important topic, and the data that do exist are overwhelmingly from humans and their close relatives or from laboratory models such as mice. Here, we compare data on shape, variance and integration through postnatal ontogeny for a placental mammal, the least shrew, Cryptotis parva, and a marsupial mammal, the gray short-tailed opossum, Monodelphis domestica. Cranial variance decreased dramatically from early to late ontogeny in Cryptotis, but remained stable through ontogeny in Monodelphis, potentially reflecting functional constraints related to the short gestation and early ossification of oral bones in marsupials. Both Cryptotis and Monodelphis showed significant changes in cranial integration through ontogeny, with a mixture of increased, decreased and stable levels of integration in different cranial regions. Of particular note is that Monodelphis showed an unambiguous decrease in integration of the oral region through ontogeny, potentially relating to their early ossification. Selection at different stages of development may have markedly different effects if patterns of integration change substantially through ontogeny. Our results suggest that high integration of the oral region combined with functional constraints for suckling during early postnatal ontogeny may drive the stagnant variance observed in Monodelphis and potentially other marsupials.

Maternal behavior of the Eurasian lynx Lynx lynx L. during the early postnatal ontogeny of its cubs

The dynamics of the major elements of maternal behavior of Eurasian lynx females during the first month of life of their cubs and their association with litter parameters (number of kittens, sex, and mass) have been traced. By the end of the first month, the amount of time spent by the female outside of the den significantly increases. An association between the litter size and maternal behavior has been found. Females rearing small litters spend more time outside of their den; they also spend more time on allogrooming of each separate kitten than females with large litters. Concerning allogrooming duration, a preference for male kittens by lynx females has been noticed in the third week.

Development of the Ordered Organization of Corticocortical Connections between Field 17 and the Posteromedial Wall of the Lateral Suprasylvian Sulcus in Early Postnatal Ontogeny in Cats

The development of the clustered organization of corticocortical connections between visual field 17 and the posteromedial wall of the lateral suprasylvian sulcus (field PMLS) was studied in cats. The retrograde axonal marker horseradish peroxidase was microinjected into the PMLS region. The distribution of labeled initial neurons was analyzed in field 17 in kittens aged five and 12 weeks. A significant increase in the area of cortex containing labeled neurons and a decrease in their distribution density were seen between week 5 and week 12. Analysis of Fourier amplitude and phase spectra demonstrated differences in the distributions of labeled neurons in kittens of different ages and provided evidence of the incomplete formation of the clustered organization of connections in these animals. The temporal morphofunctional characteristics of the development of intercortical connections of the PMLS zone as compared with other visual areas of the cortex are discussed.

Coordinated expression of pro- and antiapoptotic proteins in the hippocampus of neonatal rats

We studied the contents of the apoptotic proteins Bcl-XL, Bax, and intact and active forms of caspase-3 using the immunoblot method in the hippocampus and brainstem of 3-day-old rat pups. The expression of pro- and antiapoptotic proteins in the regions of the developing brain demonstrates individual variability with a variation coefficient ranging from 10 to 40%. In the brainstem, a structure with a low intensity of apoptosis at this period of ontogeny, correlations between the expression levels of these proteins were not significant. However, in the hippocampus we observed a significant positive correlation between the levels of expression of the proapoptotic proteins Bax and the active form of caspase-3 (r = +0.653). The levels of these proteins significantly negatively correlated with the content of the antiapoptotic protein Bcl-XL (r = −0.651 and −0.740, respectively). Our data suggest coordinated expression of the apoptotic cascade proteins in the hippocampus, a brain structure with a high intensity of elimination of excessive cells during early postnatal ontogeny.

Developmental plasticity in covariance structure of the skull: effects of prenatal stress.

Environmental perturbations of many kinds influence growth and development. Little is known, however, about the influence of environmental factors on the patterns of phenotypic integration observed in complex morphological traits. We analyze the changes in phenotypic variance-covariance structure of the rat skull throughout the early postnatal ontogeny (from birth to weaning) and evaluate the effect of intrauterine growth retardation (IUGR) on this structure. Using 2D coordinates taken from lateral radiographs obtained every 4 days, from birth to 21 days old, we show that the pattern of covariance is temporally dynamic from birth to 21 days. The environmental perturbation provoked during pregnancy altered the skull growth, and reduced the mean size of the IUGR group. These environmental effects persisted throughout lactancy, when the mothers of both groups received a standard diet. More strikingly, the effect grew larger beyond this point. Altering environmental conditions did not affect all traits equally, as revealed by the low correlations between covariance matrices of treatments at the same age. Finally, we found that the IUGR treatment increased morphological integration as measured by the scaled variance of eigenvalues. This increase coincided and is likely related to an increase in morphological variance in this group. This result is expected if somatic growth is a major determinant of covariance structure of the skull. In summary, our findings suggest that environmental perturbations experienced in early ontogeny alter fundamental developmental processes and are an important factor in shaping the variance-covariance structure of complex phenotypic traits.

New Calretinin-Positive Cells with Polymorphous Spines in the Mouse Forebrain during Early Postnatal Ontogeny

Immunohistochemical studies of calretinin (CR) in forebrain structures adjacent to the anterior horn of the lateral ventricle in adult mice allowed us to detect a population of previously unknown mono- and bipolar cells whose bodies and processes were coated with polymorphous spines (PS) (Morfologiya, 135, No. 3, 7-19 (2009)). CR-positive spiny (CR(+)PS) cells did not contain GAD67 and were located in the white matter and layers V-VI of the frontal area of the dorsomedial cortex close to the cingulum, the rostrodorsal part of the caudate-putamen, the anterior olfactory nucleus, and the subependyma of the dorsolateral angle of the lateral ventricle. We report here studies of the distribution of these cells in seven-day-old mice. Comparative topographic analysis of definitive and early CR(+)PS cells showed that in seven-day-old mice, CR(+)PS cells were absent from the sites at which they were seen in adults, i.e., the anterior olfactory cortex, the cortical plate, and the inner part of the neostriatum. In addition, small numbers of CR(+)PS-like cells were seen at this age within the dorsal migration pathway, at the anterior margin of the neostriatum, along the dorsal border of the neostriatum with the corpus callosum, in the subependymal layer of the lateral wall of the lateral ventricle, and in the cingulum area. These data demonstrate that CR(+)PS cells may have a postnatal origin. Experiments to verify this hypothesis were performed using postnatal administration of bromodeoxyuridine (BrdU) to mice aged 2-4 days, followed by assessment of brain sections fixed at age 20 days. Double immunolabeling of sections for CR and BrdU demonstrated the presence of CR(+)PS cells containing postnatally supplied BrdU. These data provide evidence that at least some CR(+)PS cells undergo mitosis at postnatal age. In all probability, during the period from 7 to 20 days of postnatal development, CR(+)PS cells migrate to the sites that they occupy in adult animals.

Role of medial prefrontal NMDA receptors in spatial delayed alternation in 19‐, 26‐, and 33‐day‐old rats

Long-Evans rats were trained on spatial delayed alteration (SDA) in a T-maze following medial prefrontal cortical (mPFC) infusions of different doses of the noncompetitive NMDA-receptor antagonist, MK-801 (.125 microl; .25 microl; or .25 microlsaline, bilaterally), on postnatal day (PND) 19, 26, or 33. Pups trained on PND 19 showed almost no learning of SDA, regardless of drug condition (including saline). On PND 26, both doses of MK-801 significantly and equivalently prevented SDA learning, with performance during the final three training blocks remaining near chance levels, in contrast with 85% correct performance in the saline control group. On PND 33, substantial SDA learning was evident regardless of dose, although a modest impairment appeared in mid-training at both doses. These findings confirm previous reports of mPFC involvement in the early postnatal ontogeny of SDA and suggest a developmentally transient role of mPFC NMDA-receptor function in this task.

Stereotypic Progressions in Psychotic Behavior

Dopamine receptor supersensitivity (DARSS) often is invoked as a mechanism possibly underlying disordered thought processes and agitation states in psychiatric disorders. This review is focused on identified means for producing DARSS and associating the role of other monoaminergic systems in modulating DARSS. Dopamine (DA) receptors, experimentally, are prone to become supersensitive and to thus elicit abnormal behaviors when coupled with DA or a receptor agonist. In intact (control) rats repeated DA D₁ agonist treatments fail to sensitize D₁ receptors, while repeated D₂ agonist treatments sensitize D₂ receptors. D₂ RSS is attenuated by a lesion with DSP-4 (N-(2-chlorethyl)-N-ethyl-2-bromobenzylamine) in early postnatal ontogeny, indicating that noradrenergic nerves have a permissive effect on D₂ DARSS. However, if DSP-4 is co-administered with 5,7-dihydroxytryptamine to destroy serotonin (5-HT) nerves, then D₂ RSS is restored. In rats treated early in postnatal ontogeny with the neurotoxin 6-hydroxydopamine to largely destroy DA innervation of striatum, both repeated D₁ and D₂ agonists sensitize D₁ receptors. 5-HT nerves appear to have a permissive effect on D₁ DARSS, as a 5-HT lesion reduces the otherwise enhanced effect of a D₁ agonist. The series of findings demonstrate that DARSS is able to be produced by repeated agonist treatments, albeit under different circumstances. The involvement of other neuronal phenotypes as modulators of DARSS provides the potential for targeting a variety of sites in the aim to prevent or attenuate DARSS. This therapeutic potential broadens the realm of approaches toward treating psychiatric disorders.

Ontogeny of robusticity of craniofacial traits in modern humans: A study of South American populations

To date, differences in craniofacial robusticity among modern and fossil humans have been primarily addressed by analyzing adult individuals; thus, the developmental basis of such differentiation remains poorly understood. This article aims to analyze the ontogenetic development of craniofacial robusticity in human populations from South America. Geometric morphometric methods were used to describe cranial traits in lateral view by using landmarks and semilandmarks. We compare the patterns of variation among populations obtained with subadults and adults to determine whether population-specific differences are evident at early postnatal ontogeny, compare ontogenetic allometric trajectories to ascertain whether changes in the ontogeny of shape contribute to the differentiation of adult morphologies, and estimate the amount of size change that occurs during growth along each population-specific trajectory. The results obtained indicate that the pattern of interpopulation variation in shape and size is already established at the age of 5 years, meaning that processes acting early during ontogeny contribute to the adult variation. The ontogenetic allometric trajectories are not parallel among all samples, suggesting the divergence in the size-related shape changes. Finally, the extension of ontogenetic trajectories also seems to contribute to shape variation observed among adults.

Heart Rate Variability in Kittens during Early Postnatal Ontogeny

Heart rate variability in awake kittens under resting conditions was studied during the following periods of postnatal ontogeny: newborn animals, 10-day-old animals (eye opening), 20-day-old animals (rise on the legs), and 30-day-old animals (control). Newborn animals were characterized by high activity of the sympathoadrenal system due to birth stress. The effect of stress factors increased in 10-day-old kittens, which was related to the start of functioning of distant receptors and delivery of new environmental information into the brain. The acquisition of upright posture and locomotion on the limbs were accompanied by activation of the vagus nerve in kittens. Significant changes in temporal, geometric, and spectral characteristics illustrate an increase in adaptability of the organism and possibility for independent living (particularly, by the 30th day of life).

Effect of aldosterone on the regulation of the volume of principal cells of rat cortical collecting duct epithelium in early postnatal development

A rapid nongenomic regulatory effect of aldosterone on the volume of principal cells in the cortical segment of cortical collecting ducts (CCDs) of rat kidney was studied using the fluorescent dye calcein under hypoosmotic shock conditions (280‐140 mOsm/kg). In the presence of aldosterone (10 nM), the amplitude of cell volume growth significantly decreased ( p < 0.05) and the cell volume recovery time increased twice both in adult and ten-day-old animals. Age differences were detected when the time required for the cell volume recovery under hypoosmotic conditions was determined: in the adult animals, the cell volume recovered much more rapidly (by an order of magnitude) than in the ten-day-old animals both in the control and in the presence of aldosterone ( 0.09 ± 0.02 vs 2.8 ± 0.3 and 0.21 ± 0.03 vs 4.4 ± 0.5 , respectively, p < 0.001). This was the first study to demonstrate the involvement of aldosterone in the regulation of amplitude and dynamics of changes in the volume of CCD principal cells in early postnatal ontogeny. One of the key aspects of development of the osmoregulatory function of the kidney is the development of the molecular mechanisms of regulation of sodium transport in nephron epithelial cells by aldosterone. It is known that, in early ontogeny, kidneys of altricial animals including rats are insensitive to the antinatriuretic effect of aldosterone. Regulation of sodium transport in postnatal ontogeny of the rat is detected starting from the tenth day of life, when the transition from milk feeding to independent feeding is ended. The molecular mechanisms underlying the development of hormonal sensitivity of target cells of an immature kidney have been studied insufficiently well. It is known that the main proteins involved in the transmembrane sodium transport in the principal cells of the CCDs of rat nephron are the proteins of the apical epithelial of the sodium channel (ENaC) and the basolateral sodium pump ( Na + ,a + -ATPase) [6, 7]. The intracellular sodium concentration ([ ]) in principal cells is primarily determined by the dynamic equilibrium between the sodium influx through ENaC and its efflux form the cell into the intersticium against the concentration gradient by ATP-driven Na + ,a + -ATPase. Earlier, we showed that the expression of the genes encoding these proteins is suppressed and the intracellular sodium concentration in CCD principal cells is decreased in kidneys of tenday-old animals [1, 4]. At the same time, we discovered that aldosterone had a rapid nongenomic effect expressed in maintaining an increased [ ] in CCD principal cells at a low (14 mM) sodium concentration in the ambient medium both in adult and ten-day-old rats [4]. These data led us to assume that, along with the well-known mineralocorticoid effect, aldosterone is also involved in the regulation of the volume of CCD cells in rat nephron in hypoosmotic medium and that this mechanism functions even in the preweaning period. However, the rapid nongenomic effects of aldosterone on the regulation of the volume of CCD principal cells have been studied insufficiently comprehensively. In view of above, the goal of this study was to investigate the rapid nongenomic effect of aldosterone at a physiological concentration on the volume of CCD principal cells in kidneys of ten-day-old and adult rats under hypoosmotic shock conditions. Experiments were performed with CCDs of ten- and sixty-day-old Wistar rats, which were obtained by microdissection. The changes in the cell volume were assessed by the changes in the fluorescence intensity of the intracellular dye calcein and expressed in relative units. Fluorescence intensity was measured in the cells located at the open end of a CCD fragment; the basolateral and apical surfaces of these cells are in contact with the ambient solution. Continuous fluorescence recording during cell volume changes in response to osmotic shock was performed in our modification [11]. Renal tubule fragments contained in 100 µ l of suspension in aOa culture medium were loaded on a polylysinecoated slide and loaded with the fluorescent dye calcein

Age-dependent changes in porcine alveolar macrophage function during the postnatal period of alveolarization

During early postnatal ontogeny in most mammals, the lung is structurally and functionally immature. In some species with relatively altricial lung morphology, there is evidence of a coupling between functional maturity of the pulmonary cellular immune system and alveolar maturation. Herein, we examine changes in alveolar macrophage (AM) number and function occurring during alveolarization in a more precocial species, the pig, to determine if heightened oxidative metabolism and phagocytic ability is similarly delayed until completion of lung morphogenesis. We assessed cell differential in lavage fluid and evaluated two main functional parameters of AM phagocytic response, the generation of reactive oxygen species (ROS), and particle internalization. AM functional maturation occurred mainly during the first postnatal week: the proportion of AMs, ROS generation, and phagocytosis all increased significantly. These results suggest maturational improvement of the impaired AM-based pulmonary immune system of the neonate piglet occurs during the postnatal period of rapid alveolarization.

Purinergic regulation of rat heart function in ontogeny

The effect of exogenous ATP and its analogs on heart function was studied in 14-100-day-old rats. Extracellular purines had a positive chronotropic effect on the heart. Intravenous administration of exogenous ATP and its stable analogs induced a dose-dependent increase in heart rate depending on animal age. The analysis of isometric contraction of myocardial strips demonstrated a dose-dependent positive inotropic effect of ATP. The family and subtype of the P2 receptors realizing the positive chronotropic and inotropic effects were identified using selective agonists and blockers. P2X receptors demonstrated the highest sensitivity during early postnatal ontogeny. The age-related pattern of the receptor response to exogenous purines indicated the heterochronic maturation of P2X and P2Y receptors in the myocardium.

Expression of glucocorticoid receptor in the brain of rats during postnatal ontogeny

Expression of glucocorticoid receptor protein in the hippocampus and frontal cortex of male and female rats during the 1st, 2nd, and 3rd weeks of life was studied by Western blot hybridization. In the frontal cortex, the concentration of receptor protein progressively increased from the 1st to the 3rd week of life; in females, expression of 94-kDa protein significantly surpassed that in males during the 1st week of life. In the hippocampus, expression of 94-kDa and 82-kDa proteins during the 1st week of life was higher in males. Moreover, expression of the major glucocorticoid receptor isoform (94 kDa) in this structure remained unchanged in all periods of the study in males, whereas in females it was low over the first 2 weeks of life and increased by the 3rd week. Variations in the expression of glucocorticoid receptors in the hippocampus of male and female rats coincide with changes in plasma corticosterone concentration during the early postnatal ontogeny.