Synaptic connections of physiologically identified geniculocortical axons in kitten cortical area 17.

Single geniculocortical axons were recorded in the cortical white matter of kittens and adult cats by using micropipettes filled with horseradish peroxidase (HRP). Of 41 axons recovered in 4-5 week old kittens, three well-filled axons arborized in area 17; the remainder were incomplete or arborized in area 18. One axon had Y-like physiological properties, two were X-like. They were recovered from two 34-day-old kittens. All three axons formed clustered arborizations, mainly in layer 4A. Electron microscopic (EM) analysis of 50 boutons from kitten and 38 boutons from adult controls revealed that the boutons from kitten made synapses more frequently on spines (91% of targets) than did the boutons from the adult (71%). One X-like axon in kitten also had a collateral projection that made synapses in layer 1; this has not been seen in adult cats. In overall extent, the axons from kitten fell within the adult range.     

Comparative analysis of the interactions between spontaneous active neurons of the sensomotor cortex of kittens and adult cats

The character of functional interneuronal relations in the sensorimotor cortex during spontaneous neural activity in kitten and adult cats immobilized with d-tubocurarine, was studied by the method of cross-correlations of two impulse series. The data obtained by computation revealed specific age-related interneuronal connections in investigated groups of animals. In kitten aged up to 10 days, the highest percentage of the functional connections was observed which were established mainly due to the influence of a common source. In other groups of animals (kittens of 20, 30 days of postnatal life, adult cats) the common source did not play a significant role in the formation of interneuronal connections. The results showed that inhibitory connections between neurones-are established to the end of the first month of the postnatal life.     

Transplacental Neospora caninum infection in cats

Transplacental transmission of Neospora caninum was studied in 2 pregnant cats (queens). Queen 1 was inoculated subcutaneously with 2 x 10(6) cell culture-derived N. caninum tachyzoites on day 47 of gestation. She gave birth to a full-term kitten on the 17th day after inoculation. The kitten died the second day after birth due to generalized N. caninum infection. The mother cat was killed on the third day after parturition and was found to have a macerated kitten in the uterus. Severe placentitis, metritis, hepatitis, and nephritis due to N. caninum were seen in tissues from the queen. Queen 2 was fed N. caninum tissue cysts and mated 111 days later. She gave birth to 3 healthy full-term kittens. The kittens were necropsied at 2, 22, and 30 days of age. Neospora caninum was recovered from the organs and was seen in histologic sections in 1 of the 3 kittens. Results indicate that N. caninum can be transplacentally transmitted in cats during acute and chronic stages of infection. Neospora caninum-specific IgG antibodies were demonstrated in the sera of inoculated cats and nursing kittens.     

DNA methylation status in somatic and placenta cells of cloned cats

We recently produced 11 cloned kittens by somatic cell nuclear transfer (SCNT) using fibroblasts from a feline fetus (donor A, three kittens), an adult domestic cat (donor B, one kitten), and a deaf adult Turkish Angora cat (donor C, seven kittens). Two kittens were stillborn and three died a month after birth. The donor C-derived kittens did not share their donor's eye color or deafness. To test whether this and the low cloning success rate are due to epigenetic modifications, we compared the methylation of somatic and placental cells from the cloned cats and domestic normal cats by bisulfite mutagenesis sequencing analysis. The DNA methylation of somatic cells from the cloned kittens ranged from 78.0% to 88.9%, and did not differ significantly depending on whether they were stillborn, died early after birth, or were healthy. Donors B and C showed similar levels of methylation (77.0% and 79.1%, respectively), as did somatic cells from normal domestic and Turkish Angora cats (range, 75.7-88.0%). However, donor A showed less methylation (70.6%) than the somatic cells from the kittens derived from it (range, 82.2-88.9%). Moreover, placental cells from three donor C-derived kittens showed significantly higher DNA methylation (range, 76.7-80.5%) than placental cells from normal domestic cats (range, 64.2-74.9%). Thus, methylation of satellite regions in somatic cells may not be responsible for the stillbirth, early death, or different eye and hearing attributes of cloned cats. However, hypermethylation in the placenta of cloned cats may be responsible for low success rates in cloning cats.     

Fluorescent two-dimensional difference gel electrophoresis and mass spectrometry identify age-related protein expression differences for the primary visual cortex of kitten and adult cat

The recent introduction of fluorescent two-dimensional difference gel electrophoresis, combined with mass spectrometry, has greatly simplified the analysis and identification of differentially expressed proteins by eliminating intergel variability. In this report, we describe the successful application of this functional proteomics approach to compare protein expression levels in visual cortical area 17 of adult cats and 30-day-old kittens, in order to identify proteins expressed in an age-related fashion. We identified 16 proteins that were more abundantly expressed in kitten striate cortex and 12 proteins with a pronounced expression in adult cat area 17. Among those isolated from kitten area 17 were proteins related to axon growth and growth cone guidance and to the formation of cytoskeletal filaments. Glial fibrillary acidic protein, as identified in adult cat area 17, has been implicated previously in the termination of the critical period for cortical plasticity in kittens. In situ hybridization experiments for two of the identified proteins, glial fibrillary acidic protein and collapsin response mediator protein 5, confirmed and extended their differential expression to the mRNA level. Our findings show that two-dimensional difference gel electrophoresis combined with mass spectrometry is a powerful approach that permits the identification of small protein expression differences correlated to different physiological conditions.     

Age differences in responsiveness of brainstem chemosensitive neurons to extracellular pH changes

The sensitivity of neurons in the caudal chemosensitive area on the ventrolateral surface of the medulla oblongata (VMS) to extracellular pH changes was examined in newborn and young developing kittens and compared to that of adult cats. The pH was varied by superfusion of the VMS with mock cerebrospinal fluid (CSF) of pH 7.4 (control), 7.0 (acid) and 7.8 (alkaline). A total of 97 neuronal units in the three age groups changed their firing rates inversely in response to extracellular fluid (ECF) pH changes. The greatest sensitivity was found in the adult group where acid superfusion caused an increase in neuronal activity. The least sensitivity was observed in the newborn group (1-6 days old), whereas the young kitten group (4-6 weeks old) exhibited an intermediate sensitivity. Neurons of kittens older than 7 weeks of age demonstrated a response pattern characteristic of the adult group. Neurons of neonates older than seven days, exhibited a response pattern characteristic of the young kitten group.     

Production of second-generation cloned cats by somatic cell nuclear transfer

We successfully produced second-generation cloned cats by somatic cell nuclear transfer (SCNT) using skin cells from a cloned cat. Skin cells from an odd-eyed, all-white male cat (G0 donor cat) were used to generate a cloned cat (G1 cloned cat). At 6 months of age, skin cells from the G1 cloned cat were used for SCNT to produce second-generation cloned cats. We compared the in vitro and in vivo development of SCNT embryos that were derived from the G0 donor and G1 cloned donor cat's skin fibroblasts. The nuclei from the G0 donor and G1 cloned donor cat's skin fibroblasts fused with enucleated oocytes with equal rates of fusion (60.7% vs. 58.8%, respectively) and cleavage (66.3% vs. 63.4%). The 2-4-cell SCNT embryos were then transferred into recipients. One of the five recipients of G0 donor derived NT embryos (20%) delivered one live male cloned kitten, whereas 4 of 15 recipients of the G1 cloned donor cat derived NT embryos (26%) delivered a total of seven male second-generation cloned kittens (four live kittens from one surrogate, plus two stillborn kittens, and one live kitten that died 2d after birth from three other surrogate mothers). The four second-generation cloned kittens from the same surrogate all had a white coat color; three of the four second-generation cloned kittens had two blue eyes, and one of the second-generation cloned kittens had an odd-eye color. Despite low cloning efficiency, cloned cats can be used as donor cats to produce second-generation cloned cats.     

Differential phosphorylation of tau proteins during kitten brain development and Alzheimer's disease

Differential distribution and phosphorylation of tau proteins were studied in developing kitten brain by using several antibodies, and was compared to phosphorylation in Alzheimer's disease. Several antibodies demonstrated the presence of phosphorylated tau proteins during kitten brain development and identified pathological structures in human brain tissue. Antibody AD2, recognized tau in kittens and adult cats, but reacted in Alzheimer's tissue only with a pathological tau form. Antibody AT8 was prominent in developing kitten neurons and was found in axons and dendrites. After the first postnatal month this phosphorylation type disappeared from axons. Furthermore, dephosphorylation of kitten tau with alkaline phosphatase abolished immunoreactivity of AT8, but not that of AD2, pointing to a protection of the AD2 epitope in cats. Tau proteins during early cat brain development are phosphorylated at several sites that are also phosphorylated in paired helical filaments during Alzheimer's disease. In either event, phosphorylation of tau may play a crucial role to modulate microtubule dynamics, contributing to increased microtubule instability and promoting growth of processes during neuronal development or changing dynamic properties of the cytoskeleton and contributing to the formation of pathological structures in neurodegenerative diseases.     

Fatal Neospora caninum infection in kittens

Three 3-day-old kittens were inoculated subcutaneously and orally with Neospora caninum tachyzoites. A littermate and the queen were not inoculated with N. caninum and served as controls. Kitten 1 died between 14 and 16 days postinoculation (DPI) and was eaten by the mother. Kitten 2 died 17 DPI and kitten 3 was euthanized 29 DPI in a moribund condition. The control littermate and the dam remained healthy. Granulomatous skeletal myositis and nonsuppurative encephalomyelitis were the main lesions and were associated with numerous N. caninum tachyzoites in kittens 2 and 3. Cysts were found in kitten 3. Oocysts were not found in any cats. Neither lesions nor parasites were found in control cats.     

Ontogenesis of the asymmetry of transcallosal responses in the cat parietal cortex

In acute experiments on 2-24 days old immobilized kittens and adult cats, studies have been made on the development of functional interhemispheric asymmetry of homotopical transcallosal responses in the parietal cortex. It was found that the number of animals with evident asymmetry increases with age. Alongside, with respect to such characters as asymmetry coefficient, mean amplitude of components of transcallosal components and the ratio of zones of direct and inverse domination, the increase in functional interhemispheric asymmetry was observed during the second week of postnatal life of kittens, which was accompanied by the inversion of its sign; in adult cats, the decrease in the asymmetry up to its complete absence was found. The data obtained are discussed with respect to peculiarities of the development and functional properties of the associative parietal cortex in cats.     

Expiratory effects of vagal stimulation in newborn kittens

Expiratory effects of electrical stimulation of vagal afferents were studied in 12 kittens during the first week of life. Animals anesthetized with ketamine (30 mg/kg, im) and acepromazine (1.1 mg/kg, im), tracheostomized, and paralyzed were artificially ventilated after bilateral vagotomy. Rectified and "integrated" activity of the C5 root of phrenic nerve, systemic blood pressure, and the stimulus train were recorded. The optimal stimulus parameters for expiratory prolongation were chosen. The results varied between animals. We found three types of response: A, expiratory prolongation when stimulus was applied within the initial 80% of control expiratory time (TEc); beyond this delay, a decreased response or no effect was observed in four kittens; B, graded expiratory prolongation was recorded to the end of this phase in three kittens; and C, expiratory prolongation when stimulus delay was less than 40% of TEc and expiratory shortening when the stimulus given with greater delays was observed in one kitten. Nonsignificant effects were observed in the remaining four animals. Types A and B of response suggest activation of the slowly adapting pulmonary stretch receptors. However, amplitude of stimulus and frequency of pulses were higher than those used in adult animals. Type C response indicates that fibers from both rapidly and slowly adapting stretch receptors could be activated. Our results imply that if the expiratory insensitive phase is present in kittens, it can be affected by experimental conditions. This is in contradiction to characteristics of expiratory response to vagal stretch receptor input in adult cats.     

Response of the kitten to dietary taurine depletion: effects on renal reabsorption, bile acid conjugation and activities of enzymes involved in taurine synthesis

Kittens were adapted to a semipurified diet and then fed either a control diet that contained 0.1% taurine or a taurine-free diet for 6 weeks; at the end of the feeding period, kittens fed the taurine-free diet had plasma and liver taurine concentrations that were 0.38 and 0.15%, respectively, of those for control kittens. Hepatic cysteinesulfinate decarboxylase activity in taurine-deficient kittens was five-times the level in control kittens, but hepatic cysteine dioxygenase activity was not affected by the dietary treatment. Taurine-conjugated bile acids made up 98% of the total bile acids in the gall bladder of control kittens, but they accounted for only 44% of the total bile acids in the bile of taurine-depleted kittens; both the concentrations of taurine-conjugated bile acids and total bile acids were markedly decreased in taurine-deficient kittens. No effect of taurine depletion on the fractional excretion of taurine in the urine was observed. The kitten may have some mechanisms for adapting to a low-taurine diet, but these are clearly not sufficient to maintain tissue taurine levels in the absence of dietary taurine.     

Activity of caudal mesenteric ganglion in relation to its impulsation (age aspect)

It has been shown in acute experiments on cats and kittens that the pre- and postganglionic nerves of the caudal mesenteric sympathetic ganglion (CMSG) are bioelectrically active from the first day of the animal's life. When the impulsation which comes to the ganglion along the afferent and preganglionic fibers is removed, the impulse activity of the post-ganglionic neurons disappears completely. In newborn kittens the level of activity of the postganglionic fibers is determined to a greater degree by the afferent impulsation of the hypogastric nerves than in adult cats. The effect of the preganglionic impulsation, especially that coming through the intramesenteric nerves, predominates in adult animals. The efferent impulsation of the hypogastric nerves in cats not older than five days disappeared after sectioning of two to three preganglionic branches of the CMSG; in six to nine and 14 to 15-day-old cats, after sectioning of four and in month old cats after sectioning of five; and in two to three month old cats after sectioning of six branches. In adult cats after the first sectioning the postganglionic impulsation frequently intensified, and after sectioning of seven branches the activity completely disappeared. Automatic activity of the ganglia was not observed, postganglionic impulsation developed and changed under the influence of the impulses coming to the ganglion.Scientific Research Institute of Childhood and Adolescent Physiology, Academy of Pedagogical Sciences USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 5, pp. 533–542, September–October, 1971.     

Congenital transmission of Schistosoma japonicum in the rabbit

Fourteen pregnant rabbits were each infected with 300 cercariae of Schistosoma japonicum and divided into two groups. Group M (n = 8) was infected during mid-gestation (the organogenetic stage) and group L (n = 6) was infected during late-gestation (the post-organogenetic stage). Mother rabbits and rabbit kittens were killed 45-60 days after infection and perfused in order to obtain worm counts. Furthermore, faecal egg counts and tissue egg counts from livers were obtained from the mother rabbits as well as the rabbit kittens. All mother rabbits became infected harbouring 207.6 +/- 20.2 and 220.0 +/- 27.5 adult worms in group M and L, respectively. In groups M and L, 13.5% and 46.7% of the kittens were infected, respectively. In 12 of 14 litters at least one kitten was infected. The infected kittens harboured between one and three adult S. japonicum. The livers of the kittens infected with a worm pair displaced lesions as a result of egg deposition. The results, therefore, show that congenital transmission of S. japonicumcan occur in rabbits. The close anatomical resemblance between the rabbit and human placenta may be indicative of the presence of congenital transmission of S. japonicum infection in humans.     

Investigation of the faecal microbiota of kittens: monitoring bacterial succession and effect of diet

Weaning is a stressful process for kittens and is often associated with diarrhoea and the onset of infectious diseases. The gastrointestinal (GI) microbiota plays an essential role in host well-being, including improving homoeostasis. Composition of the GI microbiota of young cats is poorly understood and the impact of diet on the kitten microbiota unknown. The aims of this study were to monitor the faecal microbiota of kittens and determine the effect(s) of diet on its composition. Bacterial succession was monitored in two groups of kittens (at 4 and 6 weeks, and 4 and 9 months of age) fed different foods. Age-related microbial changes revealed significantly different counts of total bacteria, lactic acid bacteria, Desulfovibrionales, Clostridium cluster IX and Bacteroidetes between 4-week- and 9-month-old kittens. Diet-associated differences in the faecal microbiota of the two feeding groups were evident. In general, fluorescence in situ hybridization analysis demonstrated bifidobacteria, Atopobium group, Clostridium cluster XIV and lactic acid bacteria were dominant in kittens. Denaturing gradient gel electrophoresis profiling showed highly complex and diverse faecal microbiotas for kittens, with age- and/or food-related changes seen in relation to species richness and similarity indices. Four-week-old kittens harboured more diverse and variable profiles than those of weaned kittens.     

Effects of caffeine on carotid sinus nerve chemosensory discharge in kittens and cats

Bairam, A., P. De Grandpré, C. Dauphin, and F. Marchal. Effects of caffeine on carotid sinus nervechemosensory discharge in kittens and cats. J. Appl.Physiol. 82(2): 413-418, 1997.Caffeine (C)decreases apneic episodes in premature infants and is thought tostimulate breathing mainly by a central mechanism. While the methylxanthines theophylline and aminophylline are known to alter thecarotid chemoreceptor activity, there are little data on C. The aim ofthe study was to examine the effects of C on the carotid sinus nervedischarge (CSND) in developing animals. Nine kittens 17-21 daysold and six adult cats that were anesthetized and artificially ventilated were studied. They received four consecutive doses of C,each of 10 mg/kg, administered at intervals of 20 min either asintravenous bolus injection (6 kittens, 3 cats) or continuous infusion(3 kittens, 3 cats). Bolus injections of C invariably induced a promptbut transient increase in the CSND from 4.1 ± 0.6 to 8.1 ± 1.0 (SE) impulses/s in kittens (P = 0.01)and from 3.9 ± 0.1 to 7.9 to 1.0 impulses/s in cats (after thefirst injection). This response was associated with a significantdecrease in arterial blood pressure. Continuous infusion of C did notinduce any early change in either CSND or blood pressure in kittens orcats. Fifteen minutes after C injection or infusion was begun, CSNDvalues in air, 8% O₂-balanceN₂, or 100%O₂ were not significantlydifferent from control. Haloperidol administered at theend of the experiment in four cats and four kittens significantlyincreased CSND and did not suppress the early response to C injection.It is concluded that caffeine administered by bolus in the kitteninduces a transient stimulation of the CSND that is associated with adecrease in the arterial blood pressure and is independent of thedopaminergic mechanisms in the carotid body. The lack of sustainedeffect implies the main mechanism to the ventilatory stimulation by Cmust be central.

     

The consequences of differences in litter size for the nursing cat and her kittens

Seventy-one litters of kittens (mean litter size 4.4) were studied from birth to eight weeks of age in order to measure kitten growth and maternal body condition. Few sex differences in growth occur; male and female kittens place a similar burden on their lactating mother. A mother's weight (non-pregnant, non-lactating) interacts with litter size to determine the fate of her growing kittens. A large litter places a burden on both the mother and on the kittens, whose growth is affected; small mothers with large litters are particularly at risk. An acceleration in kitten growth occurs at about 32 days as the kittens take more solid food. This change in growth rate is more marked in large litters. Kittens of light mothers and kittens in large litters are weaned at a lower weight, and kittens of light mothers are weaned earlier. Our results indicate that, under poor environmental conditions, large litters would be less successful than small litters; kitten growth and survival would be affected and providing milk for a large litter would have a detrimental effect on the mother's health. The cost of lactation appears to have been a major evolutionary factor in determining mean litter size.     

The electrophysiological properties of the conduction pathways of the stellate ganglion in the cat in postnatal ontogeny]

In new-born, 10-, and 20-day-old kittens and in adult cats, the stellate ganglia branches contained both continuous and synaptically interrupted fibres. In the course of postnatal ontogenesis, the average conduction velocity of excitation and average amplitude of the responses increased. In new-born and 10-day old kittens, these are C-fibres. Apart from the latter, A delta and B fibres appeared in 20-day old kittens. In adult cats, two subgroups of all types of the fibres appeared. Since the 10-day age, synaptically interrupted responses have been recorded in anastomoses and inferior cardiac nerve following stimulation of cranial and caudal branches of the subclavian loop, the responses being conducted in both directions in adult cats.     

Anticonvulsant properties of the cerebrospinal fluid during activation of the antiepileptic system of the brain

Cerebrospinal fluid (CSF) was obtained after 30-40 sessions of daily electrical stimulation of the cat cerebellum vermis. The intraventricular injection of CSF (10 microliters) to Wistar rats increased the latent period of initial seizure manifestations, significantly reduced the number of animals with seizures and reduced the severity of seizures induced by korazol injection (40 mg/kg). Analogous seizure changes were observed in rats after intraventricular injection of CSF (10 microliters) from cats subject to 3-10 electroshock seizure fits. Intraventricular injection of CSF (250 microliters) obtained from cats after electroshock to cats with strychnine-induced epileptic foci in the brain cortex led to the suppression of the epileptic activity. The conclusion was made that different ways of antiepileptic system activation cause the accumulation of endogenous antiepileptic substances in CSF.     

The reflection of the motivational status in the spectral characteristics of the species-specific acoustic signals of the domestic cat

Spectral characteristics of species-specific acoustic signals were analyzed in cats under various unfavourable conditions: hunger, isolation, pain stimulation, agony. The increase in the need to get rid of the discomfort accompanied by the development of emotional excitation was reflected in spectral characteristics of produced signals. The frequency and duration of signals increased, their spectrum widened accompanied by spectral maxima shifted towards the high-frequency area similar to the range of formant frequencies in the signals of newborn kittens. The similarity between spectral characteristics of the above signals in adult and newborn cats might indicate the appearance of infantile features in adult cats under conditions of a marked desire to change the existing situation. The fact that motivational state was reflected in spectral characteristics of acoustic signals along with stable responses to the signals, spoke in favour of a considerable contribution made by communication to the organization of intraspecific relations.