Rabbits Of Different Ages Research Articles

Changes in immunological potential between juvenile and presenile in rabbit

To investigate the relationship between immunological potential and advance of age, patterns of humoral immune response in different aged rabbits were compared. In the primary response, the appearance of total antibody and the arrival to its peak level were retarded by advance of age. On the other hand, the appearance fo IgG antibody was the earliest in young and young adult rabbits though the arrival to its peak level was the latest. The disappearance of total and IgG antibodies was earlier in older and immature animals. In the secondary response, the reincrease of total antibody occured on the same day regardless of the age, but the older were the rabbits, the earlier was the reincrease of IgG antibody and also the arrival to the peak level of both antibodies. In the primary and the secondary responses, the maximal titers of both antibodies were the highest in young and young adult groups. From these results, the exact comparison of immunological potentials in rabbits of different age is possible only by the comparison of patterns of immune responses together with their intensity.

Characteristics of pulmonary edema induced in rabbits of different ages

Young rabbits up to the age of 3 weeks are less resistant to chloramine (CA) than adult rabbits. The lethal dose of CA for the young rabbits was 40–50 mg/kg. They died from poisoning manifested as protracted collapse without any evidence of edema. The lethal dose of CA for older rabbits was 60–70 mg/kg. Death occurred from severe acute pulmonary edema. The young rabbits developed atypical pulmonary edema only after receiving very large doses of CA (200–250 mg/kg). Under these circumstances a small quantity of edema fluid was present and the predominant feature was hemorrahage, probably caused by the direct destructive action of CA, excreted through the lungs, on the walls of the arterioles and capillaries of the vascular system of the lungs.

On the regeneration of aortic endothelium at different ages

In order to study the physiological regeneration of the endothelium, “Häutchen”, preparations of aortic endothelium were produced from 15 rabbits of different ages and studied autoradiographically. By determining the number of 3H-thymidine-labelled cells, the mitotic rate and the total number of cells per 0.12 mm 2, we arrived at the following conclusions: (1) The mean generation time of endothelial cells increases with advancing age. The extension of the mean generation time of the endothelial cells, as deduced from the decrease in the 3H-thymidine labelling index and in the mitotic rate, mainly occurs during the first four months of life. (2) Neither between topologically different aortic segments nor between such portions of the aorta as are exposed to different flow-mechanical stresses could any considerable differences with regard to the reproduction rate of their endothelial cells be detected. The raised endothelial turnover in the area of the iliac bifurcation requires further studies.

Nucleic acids in articular cartilage from rabbits of different ages.

The joint cartilage of immature, adult and old rabbits was examined. The joint cartilage in adult and old rabbits contained less nucleic acids than that in young rabbits. The synthesis of DNA decreases with advancing age, while no difference was found in the concentration of nucleic acids between adult and old rabbits.

The ontogenetic development of concentration differences for protein and ions between plasma and cerebrospinal fluid in rabbits and rats

1. The purpose of this study was to study in rats and rabbits the ontogenetic development of the blood-brain barrier to macromolecules and the ontogenetic development of concentration differences between plasma and cerebrospinal fluid for ions which are known to be transported actively across the choroid plexus and the blood-brain barrier.2. By comparing the development of concentration differences for ions with the development of the blood-brain barrier to macromolecules we wanted to evaluate an eventual relationship between the development of these two functions of the blood-brain barrier.3. The concentration of protein in cerebrospinal fluid and plasma was measured in foetal, juvenile and adult rabbits and in new-born, juvenile and adult rats. The concentration of protein was similar in rabbit foetuses at 23 days of gestational age (term at 31 days) and in new-born rats, and the ratio decreases at approximately the same rate in the two species.4. The high concentration of proteins in cerebrospinal fluid might reflect either a high rate of entry of protein into the brain or a low production rate of cerebrospinal fluid. Injection of Diamox(R) (100 mg/kg) 2 hr before sampling of cerebrospinal fluid did not change the concentration of protein in cerebrospinal fluid in new-born rats whereas it increased the concentration in older rats. This finding suggests that new-born rat produces little (if any) cerebrospinal fluid suggesting that the high concentration of protein in cerebrospinal fluid in new-born rats reflect a low rate of turnover of cerebrospinal fluid.5. The concentration of sodium, potassium, chloride and magnesium in plasma and cisternal cerebrospinal fluid was measured in rabbits of different age, from 23 days of gestation until adulthood, and in rats of different ages from birth until adulthood.6. Concentration differences between plasma and cerebrospinal fluid for these were established in the youngest animals examined, indicating that the active transport mechanisms for these ions were functioning at an age where the concentration of protein in cerebrospinal fluid was very high.7. The maintenance of concentration differences for ions at a time where the concentration of proteins in cerebrospinal fluid is high, is difficult to explain if the high concentration of proteins in cerebrospinal fluid is due to a leakiness of the intercellular junctions between cerebral endothelial cells. However, the findings might be explained either by a low rate of production of cerebrospinal fluid in the youngest animals and/or by a pinocytotic transfer of proteins across the blood-brain barrier in these animals.8. In rats concentration gradients for ions are established at an age (new-borns) with a low or absent bulk formation of cerebrospinal fluid and at an age where the capillaries are still not enveloped by astrocytic foot processes. These facts suggest that the active transport mechanisms for the ions must be located in the cerebral endothelial cells.

Androgen binding protein (ABP) in rabbit testis and epididymis: Changes with age in comparison with, the androgen binding protein (TeBG) in serum and separation from the intracellular receptor in epldidymia

ABP has been measured in 105,000 g supernatants of testis and epididymls from rabbits of different ages and compared with a similar androgen binding protein (TeBG) in rabbit serum. Whereas the concentration of ABP in the caput epididymidis increased markedly from immaturity to adulthood, serum TeBG decreased, indicating that ABP and TeBG are regulated by different hormonal mechanisms. The concentration of ABP (pmoles/mg protein) in sexually mature rabbits was much higher in the epididymis than in the testis. Within the epididymis most of the ABP was concentrated within the caput, and very low amounts were found in the cauda, indicating that binding activity of ABP is destroyed as it passes through the epididymis. In addition to ABP (R f ~0.7), rabbit epididymal supernatant contains a larger binding protein for 5α-dihydrotestosterone (DHT; 17β-hydroxy-5α-androstan-3-one) with slower electrophoretic mobility (R f ~0.4) and a more rapid sedimentation rate on sucrose gradients (7S). This component is most probably the intracellular androgen receptor in the rabbit e pididymis.

Structural and biochemical maturation of the cerebral pallium in rabbit fetuses: morphogenesis and lipids.

Abstract—Morphological parameters of maturation of the cerebral pallium in rabbit fetuses ranging between 20 days of gestation (d.g.) and the early neonatal stage are expressed semi‐quantitatively and correlated with progressive changes in the brain lipids, glycolipids and nucleic acids. Dual expression of the chemical values, using as referents both the dry weight of the tissue and the DNA unit, reveal the crucial stage in brain development when rapid cell proliferation is replaced by rapid cell growth; this stage in rabbit fetuses occurred between 28 and 30 d.g. Between 20 d.g. and the early neonatal phase the RNA decreased moderately when expressed per unit of DNA. Even at the time of term birth the cortical nerve cells of the rabbit showed signs of immaturity including a relatively small nuclear volume.On the dry weight basis, the lipids of the cerebral pallium exhibited little change in composition during fetal development; however, cerebrosides rose substantially between 30 d.g. and the early neonatal phase. When expressed per unit of DNA, all lipids and glycolipids continued to increase progressively in a pattern characteristic of growth throughout the prenatal period studied. This increase was also apparent when the lipid constituents were expressed per total pallium at the progressive gestational stages.The molar ratios of phospholipids:cholesterol:cerebrosides in the pallium of rabbits of different ages were as follows: in adult rabbits‐2.9: 2.6: 1.0, in the newborn‐2.9: 1.3: 0.2 and in the 30 d.g. fetuses‐3.0: 1.2:0.44. These values reflect the fact that during maturation the content of phospholipids changes little, whereas that of cholesterol and especially erebrosides increases markedly.

Selective postnatal development of Na,K-activated-adenosinetriphosphatase in rabbit kidneys.

SummaryRenal ATPase activity was measured in rabbits of different ages. Total Na,K-activated; Mg-dependent-ATPase activity increased gradually with age from newborn to adult. Mg-dependent-ATPase, however, remained essentially unchanged and equivalent to the adult level during development. Na,K-activated-ATPase was nearly absent at birth and at 5 weeks of age approached levels comparable to those of the adult. The increase in total ATPase activity was due to this selective increase in the Na,K-activated component. The development of Na,K-activated-ATPase activity correlates well with the reported maturation of renal transport mechanisms for amino acids, p-aminohippuric acid, and sodium ion during the perinatal period.

The effect of age, species and adrenaline on the recovery of isolated atria from anoxia.

1. The rate of recovery of the force of contraction of isolated atria from different species of mature animals after 1 hour of anoxia was recorded.2. Atria from rabbits of different ages were also exposed to anoxia. Atria from rabbits, ranging in age from 8 days to 3 years, were essentially similar in their recovery from anoxia, which was significantly slower than that of atria taken from rabbit foetuses at the 25th day of gestation.3. Atria from human foetuses at 12-16 weeks of gestation recovered from anoxia much faster and more completely than any other atria studied and it is postulated that this may be due, in part, to the concentration of endogenous catecholamines being low.4. The addition of propranolol to the organ bath had no effect on the recovery of atria from anoxia but prevented the action of added adrenaline, which manifests itself in a slowing of the rate and incompleteness of the recovery.

Numbers of granulocytes in thymic imprints of rabbits of different ages and degrees of coccidial parasitism.

Counts of granulocytes were performed on thymic imprints from normal rabbits 3 days old, 2–3 weeks old, and young adults, and from young adult rabbits mildly and severely parasitized with coccidiosis. Analyses of percentages of eosinophils, heterophils, and basophils indicated no sex differences. Comparisons of relative numbers of granulocytes in normal rabbits showed that young adult rabbits possessed more eosinophils and fewer basophils than the younger groups (no differences in heterophils); 3-day-old rabbits had more eosinophils than the 2-to 3-week animals (no differences in heterophils and basophils). No differences in relative numbers of the various granulocytes were found in the mildly and severely parasitized rabbits, but there was a decrease in eosinophils in the parasitized rabbits when compared with the young normal adult rabbits. Eosinophilic leukocytes were divided into two groups: the mononuclear "tissue" line and the lobated "blood" line of development. In the 3-day-old rabbits about 95% of eosinophils were of the lobed variety but in the older normal rabbits, the two developmental lines were about equal in numbers. When compared with the normal young adult rabbits, parasitized rabbits have increased percentages of "blood" eosinophils as a result of greater numbers of band and polymorphonuclear cells.

Effect of Cx-reactive protein on immunologic reactivity of rabbits of different ages

Effect of Cx-reactive protein on immunologic reactivity of rabbits of different ages

Induction of tryptophan pyrrolase activity in starving rabbits of different ages.

SummaryInduction of liver tryptophan pyrrolase activity occurs readily in young rapidly growing male and female rabbits between 30-75 days of age when subjected to starvation for 24 hours or more. LTP activity in older rabbits between 4-10 months of age increases only slightly during 11 days of starvation. In the younger 30-75-day-old rabbits, intraperitoneal injection of 0.5 g L-tryp-tophan per kg body weight induces the enzyme between 7- to 15-fold over control values as compared to about 2-fold for 4-10-month-old animals.

Effect of estrogens on development of atherosclerosis of the coronary arteries in female rabbits of different ages

Effect of estrogens on development of atherosclerosis of the coronary arteries in female rabbits of different ages

Haemorrhage as a test of the function of the cardiovascular system in rabbits of different ages.

Haemorrhage as a test of the function of the cardiovascular system in rabbits of different ages.

Further observations on the territorial function and histology of the submandibular cutaneous (chin) glands in the rabbit, Oryctolagus cuniculus (L.)

Chinning—the deposition of secretion of the submandibular glands—is described and its role in the territorial marking of the free living Australian wild rabbits, Oryctolagus cuniculus (L.), is emphasized. The frequency of chinning and the weight and histology of the submandibular glands of a large number of free-living wild rabbits and of domestic rabbits have been studied experimentally. A small number of chin glands from hares, Lepus europaeus P. have been studied for comparative purposes. The chin glands are larger in males than in females. Sexual dimorphism appears when sexual maturity occurs. Males chin more frequently than females. The size of the gland and the frequency of chinning are correlated with social status. The glands seemed to be largest and most active during the breeding season. Castration during early life inhibited both the development of the glands and chinning in male rabbits, but in castrated females the size of the gland actually increased as compared with non-castrated animals. Histological changes connected with the secretion were studied in rabbits of different ages, of different social status, of known frequency of chinning, in castrated animals, and during the breeding and non-breeding seasons. Vacuolated secretory cells were found to be associated with heavy secretion. They were not seen in immature animals or those which did not chin frequently. In some heavily secreting animals they formed the entire glandular tissue. The vacuolated cells seemed to be secretory cells in a state of intense secretion. Dark cells were more common in males. Chin glands in hares were much smaller than those in rabbits. The vacuolated type of cells was not seen in hares.

Age characteristics of experimental myogenic thrombocytosis

A study on 45 rabbits of different ages (1.5–3–6 months) was carried out to assess the quantitative and qualitative thrombocyte changes in blood in response to a 7-week-long physical, physiological load. The data received showed that the physical load caused myogenic thrombocytosis in the blood of animals with age-specific peculiarities. The time and degree of adaptation to physical load in animals differed also. When analyzing the thrombocytograms in laboratories it is necessary to take into consideration the age and training of animals and also the dependence of quantity and quality of thrombocytes upon the myogenic factors.

STUDIES OF SMALL INTESTINE DURING DEVELOPMENT

The data indicate that hydrolysis of lactose is maximal perinatally. The increase in activity of this enzyme is dissociated from intestinal growth by the time the rabbit is 21 days old. There is passive diffusion of the lactose across an intestinal sac which is related only to concentration and not the age of the animal. When lactose is administered to rabbits of different ages, lactosuria is observed mainly in older animals.

EFFECT OF BACTERIAL ENDOTOXIN ON THE PHAGOCYTIC ACTIVITY OF THE RETICULO-ENDOTHELIAL SYSTEM IN RABBITS OF DIFFERENT AGE.

Stimulation of the phagocytic activity of the reticulo-endothelial system with bacterial endotoxin was studied in newborn rabbits in the period in which they do not actively form antibodies to bacterial antigens. A markedly accelerated clearance of colloidal carbon from the blood was found in five-day-old rabbits (tested by the technique of Biozzi, Benacerraf and Halpern 1953) when relatively high doses of endotoxin were used. It is assumed that the increased resistance to infection which may be elicited in young animals in that period is due to stimulation of cellular defence mechanisms. By comparison of the stimulating effect of endotoxin on phagocytosis in five-day-old, one-month-old and adult rabbits it was found that the phagocytic cells of the R.E.S. are more susceptible to the effect of endotoxin in adults than in newborns. This difference is evident from comparisons of the phagocytic indices K and the corrected phagocytic indices α in three age groups of rabbits stimulated with different doses of endotoxin. The possible mechanism and cause of differences in sensitivity of young and adult individuals is discussed.

Clotting patterns in the aqueos humor.

Fibrin formation in the anterior segment of the eye depends upon factors in the aqueous humor and upon components released from the surrounding tissues. To amplify our understanding of the circumstances that control clot formation, numerous experimental observations were accumulated using the anterior chamber of the rabbit as a living test tube. <h3>Methods and Materials</h3> The study was carried out on rabbits of different ages and races. The eyes were anesthetized with one-half per cent tetracaine (Pontocaine) solution and fixed with a small toothed forceps applied to the superior rectus muscle, while the animals were manually immobilized by an assistant. The standard experiment consisted in evacuation of the rabbit's anterior chamber by means of 30-gauge needles 1 in. long that were attached to 1 ml. syringes. After passing the needle through the cornea 1 mm. inside the limbus, it was advanced for about 4 mm. in a direction tangential to

Antibody formation in young rabbits immunized with erythrocytes.

Litters of young rabbits of different ages were immunized with a suspension of foreign erythrocytes. In every case, including rabbits immunized on the first day after birth, antibodies were formed (demonstrated by haemagglutination) on the fifth day after immunization. Age had no influence on the rate of antibody formation. Irradiation of young rabbits with a dose of 350 r. 48 hours prior to immunization inhibited the antibody reaction.