The number of active Purkinje cells in the microelectrod track as an indicator of maturity of the cerebellum motor function in mature- and immature-born animals

In experiments on 5 age groups of anesthetized guinea pigs (from newborns to 4 weeks of postnatal ontogenesis), activity of cerebellum Purkinje cells (PC) (IV–VII lobules of cerebellar vermis) was studied in the single track of microelectrode passing through cell layers. It has been shown that as early as several hours after birth, in the superficial layer of cerebellar cortex, there are recorded occasional background-active, but functionally mature PC in the form of simple and complex spikes and accordingly reflecting synaptic PC activation by afferent inputs of mossy and climbing fibers. The functional manifestation of the guinea pig motor behavior at this period of ontogenesis is act of their standing. At this period of ontogenesis, in the newborn and one-day old guinea pigs, on average, from 1 to rarely 11 active PC are recorded in the single microelectrode track. At the one-week age, the highest number of active PC in the track somewhat increases, predominantly at the expense of the mean from the total number of cells in the track. In the 2-week old guinea pigs the mean number of active PC in the track somewhat falls, while in the 4-week old and adult animals it again exceeds, although slightly, the maximal number of PC in the track of newborn animals. The relatively high number of active PC at the very initial period of postnatal ontogenesis can indicate importance of motor function in the congenital food-procuring reflex.     

Functional Role of Cerebellar Purkinje Cells in Ontogenesis of Postural-Motor Reactions in Mature- and Immature-Born Mammals

In experiments on guinea pigs, cats, and rats of different ages, from newborns to adults, the postural and stato-kinetic reflexes were studied with subsequent recording of electrical activity of identified cerebellar Purkinje cells (PC) in the same animals. Simultaneously in same age group of the animals, a morphometrical study of the shape and size of Purkinje cells and their nuclei was carried out. The first signs of manifestation of reflexes of standing and of the support reaction were observed in mature-born guinea pigs as early as at the first day after birth. At this time the PC fire has an irregular and low-frequency character with long inhibitory pauses and a great dispersion of the frequency-time characteristics. In the course of postnatal ontogenesis the parameter of the ratio of frequencies of simple and complex spikes increased in all the studied animals, guinea pigs, rat puppies, and kittens, but to different degrees. The complete maturation of the PC activity in the mature-born guinea pigs took 3–4 weeks after birth, whereas in the immature-born rat puppies and kittens this process took, on average, 5–6 and 8–9 weeks, respectively. By this time, all the studied postural-motor reactions were formed. The comparison of the course of formation of the frequency-time characteristics of the Purkinje cell activity in mature- (guinea pigs) and immature-born (rats and cats) animals allowed establishing that the highest rate of maturation of the Purkinje cell activity in the mature-born animals is observed during the first half, whereas in immature-born animals, during the second half of postnatal ontogenesis. A similar rate of changes also took place at maturation of postural-motor reflexes. The complete functional maturity of the Purkinje cell occurred, as a rule, at the time period when the shape and size of the Purkinje cell body became close to the definitive ones, and their vertical and horizontal diameters reached the values characteristic of adult animals.     

Postnatal development of the cerebellar Purkinje cell shape in guinea pig ontogenesis

In sagittal cerebellum sections, morphometrical study of cerebellum of mature-born animals - guinea pigs - was performed using Nissl's procedure. A change of shape and volume of Purkinje cells and their nuclei in the course of the guinea pig postnatal ontogenesis was studied. It has been shown that both the growth process itself and the rate of formation of the definite form of Purkinje cells and of their nuclei in the course of ontogenesis proceeds non-uniformly. The most intensive growth of vertical and horizontal diameters of Purkinje cells and of their nuclei is observed during the 1st and 4th weeks of postnatal life. Especially rapid is an increase of horizontal diameters of Purkinje cells and of their nuclei, which impairs the ovoid-bear-like shape to the cerebellar Purkinje cells of adult guinea pigs.     

Postnatal development of the shape of cerebellar Purkinje cells in guinea pig ontogenesis

In sagittal cerebellum sections, morphometrical study of cerebellum of mature-born animals—guinea pigs—was performed using Nissl’s procedure. A change of shape and volume of Purkinje cells and their nuclei in the course of the guinea pig postnatal ontogenesis was studied. It has been shown that both the growth process itself and the rate of formation of the definite form of Purkinje cells and of their nuclei in the course of ontogenesis proceeds non-uniformly. The most intensive growth of vertical and horizontal diameters of Purkinje cells and of their nuclei is observed during the 1st and 4th weeks of postnatal life. Especially rapid is an increase of horizontal diameters of Purkinje cells and of their nuclei, which impairs the ovoid-bear-like shape to the cerebellar Purkinje cells of adult guinea pigs.     

Dynamics of hematologic parameters and of the erythrocyte deformability index at the juvenal period of rats and guinea pigs

In experiments on Wistar rats and guinea pigs, dynamics of blood hematological parameters and of erythrocyte deformability index (DI) was studied from birth to the 3-month age. In rats, significant changes were revealed in the picture of blood for the first month of postnatal ontogenesis. The number of erythrocytes and leukocytes sharply increased, the number of reticulocytes decreased, their ratio in the degree of maturity was changed. The mean erythrocyte volume and their acidic resistance also decreased. Prior to the 4-week age, DI increased, which was accompanied by an increase in the hemoglobin hydration and flattening of the erythrocyte shape. Then DI decreased and erythrocytes acquired the more spherical shape. After the critical period of 3–4 weeks the studied parameters reached plateau. In guinea pigs, at this period of ontogenesis the hematologic parameters had sufficiently stable values, except for a DI decrease from birth to 1.5 months, then it rose without reaching the initial values. Like in the case with rats, DI had a close correlation with the erythrocyte parameter of shape (O_min).     

Dynamics of hematologic parameters and of the erythrocyte deformability index at the juvenal period of rats and guinea pigs

In experiments on Wistar rats and guinea pigs, dynamics of blood hematological parameters and of erythrocyte deformability index (DI) was studied from birth to the 3-month age. In rats, significant changes were revealed in the picture of blood for the first month of postnatal ontogenesis. The number of erythrocytes and leukocytes sharply increased, the number of reticulocytes decreased, their ratio in the degree of maturity was changed. The mean erythrocyte volume and their acidic resistance also decreased. Prior to the 4-week age, DI increased, which was accompanied by an increase in the hemoglobin hydration and flattening of the erythrocyte shape. Then ID decreased and erythrocytes acquired the more spherical shape. After the critical period of 3-4 weeks the studied parameters reached plateau. In guinea pigs, at this period of ontogenesis the hematologic parameters had sufficiently stable values, except for a DI decrease from birth to 1.5 months, then it rose without reaching the initial values. Like in the case with rats, DI had a close correlation with the erythrocyte parameter of shape (O min).     

Maturation of the activity of cerebellar Purkinje cells and the lift reaction

In experiments on guinea pigs (from newborn to adults), studies have been made on the extensor, support and lift reactions, as well as on the activity of cerebellar Purkinje cells in the same animals. First signs of immature lift, extensor and support reactions were observed already 12th after birth. At this period, mean discharge frequency in Purkinje cells was significantly lower than in the adult animals, reaching 11.5 +/- 1.2 imp/s for simple spikes and 0.45 +/- 0.05 imp/s for complex ones. Complete maturation of lift, extensor and support reactions takes place to the beginning of the 2nd week (8-9 days) of postnatal life. Within this period, significant changes in the activity of Purkinje cells were observed: mean discharge frequency of simple and complex spikes increased correspondingly up to 17.9 +/- 2.3 and 1.48 +/- 0.25 imp/s. At the same time, the mean discharge frequency in Purkinje cells, the average duration of inhibition pause, and the response latency became more stable.     

Development of the caudate nucleus of rats in postnatal ontogenesis and formation of cholinergic mediation in it]

Morphological maturation of the rat's caudate nucleus and formation of cholinergic system in it were studied in postnatal ontogenesis. Under investigation were newborn rats, 7, 14, 21 day old rats and adult animals. The growth and maturation of the caudate nucleys were most intesne during the first two postnatal weeks, it was somewhat descreased by the beginning of the third week and continued in later terms as well. The structure of dendrites and axons became complicated during the first two weeks, the axo-dendritic contacts being also formed. The neuron structure in 14 days old rats was similar to that of adult animals. The activity of acetylcholinesterase in the caudate nucleus of 7 and 14 days rats was not great. It sharply increased by the 17th day and reached the level of adults with 3 weeks after birth. Possible correlations of the morpho-chemical maturation of the caudate nucleus and formation of motor activity in rats is discussed.     

The organizational characteristics of the APUD system in mammalian lungs at different stages of ontogeny]

The organization peculiarities of APUD-system in the lungs of rabbits, rats and guinea pigs has been studied. The endocrine system in the lungs of rabbits in pre- and postnatal ontogenesis is presented by the adipocytes and neuroepithelial bodies (NEB) containing a considerable number of monoamines. The number of argyrophil adipocytes and NEBs in the lungs of 21 and more day-old adult rats seem to be less than in fetuses and newborns. Monoamines are not revealed in the endocrine rat lung structures by means of the glyoxylic acid. In the lungs of guinea pigs the single argyrophil adipocytes and NEBs are determined in the gestation period.     

Development of different types of muscle fiber in the postnatal ontogeny of guinea pigs

As demonstrates estimation of myosin ATPase and SDG activity, the guinea pig is already born with differentiated muscle fibers (MF), and the first histochemical differences between them take place in the uterine 10 days before birth. Tonic oxidative fibers of the first type, arranging hexagonally, develop especially quickly at early stages of postnatal ontogenesis. Their relative contents up to the end of the observations (185 days) do not change, and area of their transversal section increases but slightly in comparison to the phasic fibers. The main age changes of the muscle tissue are connected with formation and rearrangement of the phasic fibers. The most intensive reconstructions of the phasic fibers coincide with the period of game activity and sex maturation. In mixed muscles the part of the glycolytic fibers increase during the postnatal ontogenesis. In the process of ontogenesis the soleus muscle fully consists of oxidative fibers. The definitive level of the MF development is established after the guinea pigs have reached their sex maturation. Comparing the results of the given investigation with the previous data on development of MF in rats, it is possible to conclude that term and premature animals have various rates in development of the muscle system, however, main stages of myogenesis coincide, though they are connected with various phases of ontogenesis.     

Effect of harmaline on the complex spike shape and depression time in cerebellar Purkinje cell discharge in rat postnatal ontogenesis

Functional relationship between wave form of complex spike (CS) and depression time of simple spike (SS) in discharge of cerebellar Purkinje cells was studied after their activation with afferent climbing fiber at different terms of postnatal ontogenesis in norm and after treatment with harmaline. The experiments were carried out on three age groups of Wistar rats: rat pups (2 weeks), the adult (4–6 months), and the old animals (22–26 months). It was established that the SS duration in norm was approximately equal in rat pups, adult, and old animals, whereas it markedly decreased form the young to the old animals during the SS depression in the Purkinje cell discharge. Frequency of small action potential (lAP) and their number in the Purkinje cell discharge were approximately equal in young rat pups and adult animals, while in old animals these parameters were higher, on average, by 30%. After administration of harmaline, all CS parameters in rat pups and old animals increased in parallel with the depression time elongation. In adult rats, harmaline did not produce statistically significant changes of the mean values of CS parameters, but an increase of the simple spike depression time was observed. The obtained results allow concluding that the SS wave form and the simple spike depression time in norm are functionally coupled and change with age. The effect of harmaline on the CS wave forms as well as on interrelation of the CS duration and the CS depression time in the Purkinje cell discharge was more pronounced at the early and the late stages of Wistar rat postnatal ontogenesis.     

Hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and cholesterol 7 alpha-hydroxylase activity in neonatal guinea pig.

Optimal assay conditions for hepatic HMG-CoA reducatase activity and cholesterol 7 alpha-hydroxylase activity in the guinea pig were determined. These two enzyme activities were studied in the liver of newborn guinea pigs during the first three postnatal weeks. Hepatic HMG-CoA reductase activity of neonatal guinea pigs was similar to that of adult animals. However, cholesterol 7 alpha-hydroxylase activity of newborns was about one-third of that in adult guinea pigs. This finding suggests that the system for bile acid synthesis in the neonatal guinea pigs is underdeveloped.     

Characteristics of autogenic motor stimulation in rat pups

Studies have been made on the organization of the spontaneous motor activity during first 2 weeks of postnatal life of rats Rattus norvegicus (var albin.) by means of prolonged EMG recording from the gastrocnemius muscle and by computer analysis. Complexes of prolonged activity with a period of about 1 min, intracomplex periodicity of short pulses with a frequency 1/sec and periodicity of separate short bursts arranged into series with intervals between them of approximately 8-12 sec were observed. It was found that the main rhythm of these forms of excitation remains relatively unchanged during postnatal ontogenesis. The number of periods filled by series of short bursts decreases in postnatal development of animals, whereas the number of periods of a complete rest lasting for 1 1/2 and more minutes increases. These findings were compared with the development of sleep--wakefulness cycle in early postnatal ontogenesis.     

The red blood cells in growing guinea pigs. (Cavia cobaya). II. Communication: erythropoiesis and red blood cells in the postnatal development period

Bone-marrow smears of 175 guinea pigs aged 1-27 days and venous blood samples of 351 animals aged 1-25 days were prepared for cell counting. A significant increase of erythroblasts were found between life day 1 and 2; normoblasts increased in number synchronously with a decrease of erythroblasts after the 5th day. The percentage of the erythroid bone marrow increased from 10 to 14 during the developmental period. Beyond the perinatal period the red blood picture is characterized by the following changes: a decrease of erythrocyte count, hematocrit, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin; a constant mean corpuscular hemoglobin concentration; an increase of the reticulocyte count. The decrease of the red cell count is compensated by a decreasing oxygen affinity attained by an important increase of 2,3-DPG. Nevertheless, the stimulus for a raising erythropoiesis remains constant which can be shown by the growing percentage of erythroid cells and reticulocytes. The difference between the human postnatal development and that of the guinea pig becomes obvious. Cell counts in dependence of body masses in postnatally growing guinea pigs, veil the perinatal finding of the increase in erythrocytes up to the 5th day and the decrease of the mean corpuscular volume after the 3rd day.     

Connections of the cat stellate ganglion with target organs during postnatal ontogenesis

The enzyme horseradish peroxidase was administered into trachea, esophagus, heart, sternocleidomastoid muscle, and biceps of newborn, 10-, 20-day old kittens, and adult cats. The labeled neurons were located on the topical basis of the stellate ganglion. In newborn kittens, the largest cells take part in the heart innervation. In animals of other ages, the largest cells take part in innervation of the sternocleidomastoid muscle. The findings suggest that, in postnatal ontogenesis, neuronal organisation of the stellate ganglion is changing parallel to an enhancement of the neurons' size and ganglion section area.     

Maternal Vitamin C Deficiency during Pregnancy Persistently Impairs Hippocampal Neurogenesis in Offspring of Guinea Pigs

While having the highest vitamin C (VitC) concentrations in the body, specific functions of VitC in the brain have only recently been acknowledged. We have shown that postnatal VitC deficiency in guinea pigs causes impairment of hippocampal memory function and leads to 30% less neurons. This study investigates how prenatal VitC deficiency affects postnatal hippocampal development and if any such effect can be reversed by postnatal VitC repletion. Eighty pregnant Dunkin Hartley guinea pig dams were randomized into weight stratified groups receiving High (900 mg) or Low (100 mg) VitC per kg diet. Newborn pups (n = 157) were randomized into a total of four postnatal feeding regimens: High/High (Control); High/Low (Depleted), Low/Low (Deficient); and Low/High (Repleted). Proliferation and migration of newborn cells in the dentate gyrus was assessed by BrdU labeling and hippocampal volumes were determined by stereology. Prenatal VitC deficiency resulted in a significant reduction in postnatal hippocampal volume (P<0.001) which was not reversed by postnatal repletion. There was no difference in postnatal cellular proliferation and survival rates in the hippocampus between dietary groups, however, migration of newborn cells into the granular layer of the hippocampus dentate gyrus was significantly reduced in prenatally deficient animals (P<0.01). We conclude that a prenatal VitC deficiency in guinea pigs leads to persistent impairment of postnatal hippocampal development which is not alleviated by postnatal repletion. Our findings place attention on a yet unrecognized consequence of marginal VitC deficiency during pregnancy.     

The effect of insulin and thyroxine on the age-related dynamics of synthesis and degradation of proteins in skeletal muscles of cattle

The intensity of sarcoplasmic and myofibrillar protein synthesis in skeletal muscle homogenates of the cattle aged from 45 to 360 days is 3.5 and 3.8 times reduced, respectively, and remains at the same level in the old beef cattle aged 540 days. Exogenous insulin and thyroxin increases the sarcoplasmic and myofibrillar protein synthesis in skeletal muscle homogenates of animal at certain stages of postnatal ontogenesis. The catepsin and neutral protease activities are 2.0 and 1.7 times as low in the skeletal muscle of the cattle aged from 45 to 360 days while in the subsequent period they change slightly. Exogenous insulin decreases the catepsin protease activities but does not change the neutral protease activities in the skeletal muscle of animal at the most stages of postnatal ontogenesis. Exogenous thyroxin increases the catepsin and neutral protease activities in skeletal muscle of animals at the some stages of postnatal ontogenesis.     

Acid-base status of the blood and adenine nucleotide metabolism in ruminant erythrocytes during early post-natal development]

It has been established that data of acid-base balance in cows' and newborn calves' blood closely correlate with physiological status of animals during their initial days of postnatal ontogenesis and depend on the peculiarities of metabolism in fetus and newborn organisms. Data on the acid-base balance in blood of newborn calves under diarrhea syndrome are discussed from the point of view of the influence of rehydration therapy and "Namacit" preparation on clinical status of animals.     

Muscle fibre ontogenesis in farm animal species

In farm animals (bovine, ovine, swine, rabbit and poultry), muscle fibre characteristics play a key role in meat quality. The present review summarises the knowledge on muscle fibre characteristics and ontogenesis in these species. Myofibre ontogenesis begins very early during embryonic life, with the appearance of two or three successive waves of myoblasts which constitute the origin of the different types of muscle fibres. In small animals (rodents and poultry), a primary and a secondary generation of fibres arise respectively during the embryonic and foetal stages of development. In the largest species (bovines, sheep, pigs) a third generation arises in the late foetal or early postnatal period. Following these two or three waves of myogenesis, the total number of fibres is fixed. This occurs during foetal life (bovines, ovines, pigs and poultry) or during the first postnatal month in rabbits. Contractile and metabolic differentiation proceed by steps in parallel to myogenesis and are partially linked to each other. In bovines and ovines, the main events occur during foetal life, whereas they occur soon after birth in the pig, poultry and rabbit, but some plasticity remains later in life in all species. This comparative survey shows that the cellular processes of differentiation are comparable between species, while their timing is usually species specific.     

Changes in responses of UVB irradiated skin of brownish guinea pigs with aging

It is known that skin often shows irregular pigmentation during aging, which is frequently associated with hyperpigmentation. Many studies have utilized brownish A1 guinea pigs to investigate the pathogenesis of ultraviolet B (UVB)-induced skin pigmentation, however, responses associated with aging following UVB irradiation have not been elucidated. To characterize those responses, dorsal skin of A1 guinea pigs from 14-weeks to 5-yr old were investigated. The minimal erythema dose was found to increase with aging. Further, in pigmentation induced by UVB radiation, skin brightness (DeltaL*-value) decreased equally in both the 14-week old (young) group and in the 3-yr old (old) group of guinea pigs. The DeltaL*-value recovered in the young group from 21 d after UVB irradiation, whereas no such recovery was seen in the old group. In addition, the amount of melanin and the number of melanocytes returned near pre-irradiation levels in the young group, while they remained high in the old group. Our results therefore demonstrate for the first time that skin responses following UVB irradiation change with aging in A1 guinea pigs.