Distribution of two splice variants of the glutamate transporter GLT-1 in the developing rat retina.

The distributions of a carboxyl terminal splice variant of the glutamate transporter GLT-1, referred to as GLT-1B, and the carboxyl terminus of the originally described variant of GLT-1, referred to hereafter as GLT-1 alpha, were examined using specific antisera. GLT-1B was present in the retina at very early developmental stages. Labelling was demonstrable at embryonic day 14, and strong labelling was evident by embryonic day 18. Such labelling was initially restricted to populations of cone photoreceptors, the processes of which extended through the entire thickness of the retina and appeared to make contact with the retinal ganglion cells. During postnatal development the GLT-1B-positive photoreceptor processes retracted to form the outer plexiform layer, and around postnatal day 7, GLT-1B-immunoreactive bipolar cells appeared. The pattern of labelling of bipolar cell processes within the inner plexiform layer changed during postnatal development. Two strata of strongly immunoreactive terminals were initially evident in the inner plexiform layer, but by adulthood these two bands were no longer evident and labelling was restricted to the somata and processes (but not synaptic terminals) of the bipolar cells, as well as the somata, processes, and terminals of cone photoreceptors. By contrast, GLT-1 alpha appeared late in postnatal development and was restricted mainly to a population of amacrine cells, although transient labelling was also associated with punctate elements in the outer plexiform layer, which may represent photoreceptor terminals.

The newly inbred cohen diabetic rat: a nonobese normolipidemic genetic model of diet-induced type 2 diabetes expressing sex differences.

The newly inbred Cohen diabetic rat is an exceptional experimental model of diet-induced type 2 diabetes mellitus that is the result of secondary inbreeding nearly 30 years after it originally had been established. Animals from the original colony were selectively inbred by stringent criteria for 10 additional generations, bringing overall inbreeding to >50 generations. The metabolic phenotypes of the resulting contrasting strains, designated as the Cohen diabetic-sensitive (CDs) and -resistant (CDr) rats, were characterized. The phenotype of the CDs strain that was fed a regular diet consisted of fasting normoglycemia, normal glucose tolerance to intraperitoneal glucose loading, normal fasting insulin levels, and a normal insulin response to glucose loading. In contrast, CDs rats that were fed a custom-prepared high-sucrose low-copper diabetogenic diet became overtly diabetic: fasting glucose levels were normal or elevated, and the blood glucose insulin response to glucose loading was markedly abnormal. CDr rats that were fed a regular or diabetogenic diet did not develop diabetes and maintained normal glucose tolerance and insulin secretion. A striking sex difference was observed in CDs rats that were fed a diabetogenic diet: males had a lower growth rate and a more severe glucose intolerance pattern than females. Gonadectomy shortly after weaning did not prevent the development of the diabetic phenotype in its early phase in either sex but markedly attenuated its expression in males at a later phase, abolishing the sex differences. Alternate-day feeding, as opposed to daily feeding, also attenuated the metabolic phenotype in males. The development of the diabetic phenotype in CDs rats that were fed a diabetogenic diet was not accompanied by obesity or hyperlipidemia. The genetic profile of the strains was established using 550 microsatellite markers evenly distributed throughout the rat genome. The rate of homozygosity within strain was > or = 96%. The rate of polymorphism between the contrasting strains was 43%. We conclude that the metabolic phenotypes of the rebred colony of CDs and CDr rats and their genetic makeup render the Cohen diabetic rat a useful experimental model that is highly suitable for studying the interaction between nutritional-metabolic environmental factors and genetic susceptibility (sensitivity and resistance) for the development of type 2 diabetes. The model is also distinctively useful for investigating the effect of sex on the expression of the diabetic phenotype.

A comparative analysis of the maternal behavior and infant development of golden hamster (Mesocricetus auratus) and albino rats (Rattus norvegicus)

Maternal care is very important for infant development, mainly for altricial species such as rodents. This study was carried out in order to analyze the differences between the maternal behavior and infant development in two species of rodents regarded as gregarious and solitary. Thus, the behavior of 40 lactating females (20 golden hamster and 20 albino rat mother, or GH and AR) and their litters was recorded from the 1st to the 35th day after partirition. On the 4th day, litters were culled to 4 pups (all males or all females) and animals were grouped as follows: Groups I and II (litters consisting of all-male or all-female GH pups) and Groups III and IV (litters consisting of all-male or all-female AR pups). It was noted that GH mother spent a higher mean time in bodily interactions with pups and nest-building activity. All mothers axhibited higher pup retrievals and licked their pups more frequnatly around the 15th day, but GH mother exhibited a higher mean number of pup retrievals and licked their pups less frequantly. The emergence of pup self-licking around the 15th day coincided with the abrupt decrease in the maternal licking in both GH and mother. GH gained body mass more rapidly and their mothers lost a significant amount of body weight during the lactation, in contrast to the body weight gain by AR mother during the same period: On the 20th day, GH and AR mother exhibited 88.6 percent and 110.8 percent of their body mass, respectively, suggesting that the rearing costs are higher for GH mothers. We concluded that the behavior of animals may be explained in accordance with the differences in their habitats (desert or savanna), level of gregariousness, and also the characteristics of pup development.

Aspects of postural development in the rat.

The activation patterns in the longissimus and gastrocnemius muscles during the development of the mature type of locomotion were studied in rats from the 11th day until maturity. The EMG's of these muscles were recorded and movements were simultaneously recorded on videotape. Results indicate that during locomotion at early ages, the longissimus muscles are activated irregularly. From the 16th day, the bursts in the longissimus muscle become more pronounced. During locomotion, they are activated differentially and often a simultaneous activation of the longissimus and the contralateral gastrocnemius muscle was observed. From the 20th day, bursts in the gastrocnemius muscle during walking coincide with bursts in the ipsilateral longissimus muscle. Our results demonstrate that the mature type of postural control (from the 20th day) develops a few days after the development of the mature type of fluent walking (around the 15th-16th day).

Changes in body weight and organ weight of Ishibashi (IS) rats with growth.

Changes in body weight (25-175 days old, every 10 days) and weights of various organs (70, 105, 140 and 175 days old), i.e., cerebrum, cerebellum, pituitary gland, thyroid gland, thymus, heart, liver, spleen, adrenal gland, kidney, seminal vesicle, prostate, epididymis, testes, bulbourethral gland and ovary, of Ishibashi (IS) rats with growth, which are model animals for congenital vertebral malformation (spontaneous kyphoscoliosis) were examined as compared with Brown Norway (BN) rats, which are genetically irrelevant to IS rats, and also with hybrid rats (IBF, rats) which are between IS and BN rats. The experimental results showed that body weight and weights of various organs except cerebrum, cerebellum and thymus were greater in IS rats than in BN rats, and body weight and weights of various organs of IBF, rats were intermediate between the two strains of rats.

Morphology of NADPH-diaphorase-positive cells in the retinoceptive layers of the developing rat superior colliculus.

We have used diaphorase histochemistry to study the morphology of cells expressing nitric oxide synthase in the superficial layers of the superior colliculus of developing and adult rats. The nitric oxide synthase-positive cells showed a Golgi-like morphology and were classified according to the cell types identified by several authors using the Golgi method. The first nitric oxide synthase-positive cells appeared at postnatal day 7 and the number of stained cells increased progressively reaching a maximum at postnatal day 15. The poor staining of the dendritic tree and cell bodies in animals younger than postnatal day 15 allowed no unambiguous identification of the different cell types before that age. At postnatal day 15, based on cell soma and dendritic morphology, we have found that the following cell types express nitric oxide synthase: marginal, horizontal, narrow and wide-field vertical and stellate. In the adult, the same cell types were found to express nitric oxide synthase but the staining intensity and frequency of each cell type was different from the developing animal. Our results show that cells expressing nitric oxide synthase constitute a subpopulation of neurons in which all cell types are represented. Furthermore, our observations of nitric oxide synthase expression by collicular cells starting by the end of the first postnatal week and reaching a maximum by postnatal day 15 parallels the functional development of the retino-collicular and cortico-tectal projections and suggest that nitric oxide synthase-positive cells might be involved in this process.

Epi- and metaphyseal morphology in the long bones of BDIX/Han rats.

Development and morphology of the epiphyses of the long bones were investigated in 93 adult rats of 7 different strains (BDIX/Han, BDE/Han, BN/Han, DA/Han, LEW/Han, AVN/IpcV/Wistar/Rehbrücke, Shoe: WIST) from the age of 14 weeks up to the age of 78 weeks. Strain-related differences were found in the development of the secondary centre of ossification, which was retarded in the BDIX/Han rats. Furthermore, closure of the growth plate started earlier in the BDIX/Han rats. In addition various regressive changes were detected in the growth plates of long bones of all rats, but not of the ribs. The frequency and extent of these changes varied between individuals and strains. Degeneration of the matrix and necrosis were already observed at 14 weeks of age.

Iron and copper metabolism in analbuminaemic rats fed a high-iron diet.

The metabolism of iron and copper in male Nagase analbuminaemic (NA) and Sprague Dawley (SD) rats was compared. Relative liver weight was higher and spleen weight significantly lower in NA than SD rats. In NA rats, red blood cell count, haemoglobin and haematocrit were lower, whereas plasma transferrin, total iron-binding capacity and mean corpuscular haemoglobin were higher when compared with SD rats. Iron concentrations in plasma, liver, kidneys and heart were higher, and those in the spleen and tibia were lower, in NA rats. The iron concentrations in liver and spleen were positively correlated with the amount of brown pigment as observed histopathologically. Bile flow as well as biliary iron and copper excretion were higher in NA than SD rats. Copper concentrations in liver, kidneys and plasma were higher in NA rats. Plasma levels of ceruloplasmin were about two-fold higher in NA rats. The feeding of a high-iron diet reduced kidney copper concentrations in both strains of rats, which was associated with a decrease in the absorption and biliary excretion of copper.

Morfometria de ratos Wistar: pesos e medidas corporais / Morphometry of Wistar rats

Apresenta-se a evoluçäo do peso corporal e de medidas cranianas, do esqueleto axial e apendicular, em ratos Wistar. Os animais foram medidos desde o 30§ até o 180§ dia de vida pós-natal, com intervalos de 10 em 10 dias. Säo mencionadas também as condiçöes de criaçäo dos animais. Foram observados: peso corporal maior em machos, em todas as idades, ocorrendo um pico de crescimento entre 30 e 40 dias; as medidas do esqueleto apendicular de machos säo maiores do que as das fêmeas, em todas as idades; quanto às medidas do crânio, säo semelhantes até os 50-60 dias, diferindo dessa idade; o comprimento do corpo e do esterno é maior em machos do que em fêmeas (em todas as idades); a cauda dos machos só ultrapassa o comprimento da cauda das fêmeas a partir dos 60 dias

Biological evaluation of protein quality of sorghum as affected by insect infestation

Protein quality of sorghum grains having 25, 50 and 75 percent infestation caused by mixed population of Trogoderma granarium Everts and Rhizopertha dominica Fabricius was biologically evaluated by rat growth and nitrogen balance studies. Feeding of diet containing insect infested sorghum grains (50 and 75 percent) resulted in marked decrease in food intake, protein intake, gain in body weight, food efficiency ratio, protein efficiency ratio, nitrogen consumption, nitrogen absorption, biological value, net protein utilization, dry matter digestibility, net protein retention and protein retention efficiency. These parameters showed negative association with insect infestation levels. However, 25 percent level of grain infestation did not affect these parameters significantly (AU)

Changes in serum and lipoprotein fatty acids of growing rats fed protein-deficient diets with low or adequate linolenic acid concentrations.

The effects of a protein-deficient diet associated with sunflower oil [adequate in 18:2(n-6), poor in 18:3(n-3)] or soybean oil [adequate in both 18:2(n-6) and 18:3(n-3)] on lipid serum and lipoprotein compositions were studied in growing rats. Four groups of rats were fed different diets: SFC (20% casein + 5% sunflower oil); SFd (2% casein + 5% sunflower oil); SC (20% casein + 5% soybean oil); Sd (2% casein + 5% soybean oil). After 28 d, both protein-deficient groups exhibited low concentrations of protein, phospholipid, triacylglycerol and total cholesterol in serum and VLDL. Compared with rats fed 20% casein diets, those fed low protein diets had lower 18:2(n-6) and 20:4(n-6) in phospholipids of serum, VLDL and HDL2-3, and the 20:4(n-6)/18:2(n-6) ratio was twofold higher in triacylglycerols of serum and VLDL. In the SFd-fed group, 22:5(n-6) was higher than in the SFC-fed group for both triacylglycerols and phospholipids in overall lipoprotein fractions studied. In addition, the 20:3(n-9)/20:4(n-6) ratio was 0.1 in HDL2-3 phospholipids of the SFd-fed group. Sunflower oil-fed rats compared with soybean oil-fed rats had greater monounsaturated fatty acids and lower total (n-3) fatty acids in both triacylglycerols and phospholipids of serum, VLDL and HDL2-3, as well as lower total (n-6) fatty acids in serum and VLDL triacylglycerols. Apolipoproteins (apo) of VLDL were drastically depressed in rats fed protein-deficient diets, whereas apo-AI of HDL2-3 showed a particular resistance. Likewise, sunflower oil-fed rats had enhanced apo-B48 of VLDL and apo-C, apo-AII and apo-AIV of HDL2-3. The present findings show that some effects of protein malnutrition were enhanced by alpha-linolenic acid deficiency, in particular reduced (n-6) and (n-3) fatty acid bioavailability.

Differences in GH secretion from individual somatotropes in rats genetically selected for fast and slow growth.

A reverse hemolytic plaque assay was used to examine effects of selection for fast (F) and slow (S) growth on growth hormone (GH) secretion by individual somatotropes. Anterior pituitaries (AP) from 32 male Charles River CD strain rats selected for F and S growth for 20 generations were used. Four rats per line were used at 4, 6, 8, or 10 wk of age. Body weight (P < 0.0001) of F rats was greater compared with S rats. AP (P < 0.05) were heavier at 8 and 10 wk of age in F compared with S line rats. Percentages of GH-secreting cells were unaffected by age (range = 32.7-35.5%) and line [F = 33.1 +/- 1.2% (SE) vs. S = 34.5 +/- 1.2%] or by human GH-releasing factor (hGRF). At 8 and 10 wk, mean plaque-forming area was greater (P < 0.0001) in F compared with S rats under both nonstimulated (2,704 +/- 202 vs. 1,648 +/- 202 microns2) and hGRF-stimulated secretion (4,503 +/- 202 vs. 2,682 +/- 202 microns2). Results indicate that differences in growth observed in the two lines may be due to a greater secretory capacity of individual somatotropes rather than to a greater percentage of somatotropes or sensitivity of somatotropes to secretagogue.

Postnatal ontogenesis of vasopressin receptors in the rat collecting duct.

The ontogenesis of vasopressin receptors in the rat collecting duct was studied by measuring the binding of [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-O-methyltyrosine,4-threonine,8-ornithine,9-125I-tyrosylamide+ ++]-vasotocin (125I-d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH(9)2]-OVT) to isolated cortical collecting ducts (CCD), outer medullary collecting ducts (OMCD) and inner medullary collecting ducts (IMCD) microdissected from collagenase-treated kidneys of 2- to 34-day-old rats and adult animals. The stereospecificity for recognition of a series of seven vasopressin structural analogues by CCD and OMCD receptors reveals that the labeled binding sites identified in 11- to 16-day-old and adult rats are homologous respectively and contain a major population of V2 type and a minor population of V1a type of vasopressin receptors. At all postnatal stages examined, the receptor density (expressed as 10(-18) mol radioligand bound per square millimeter tubular outer surface area) decreases gradually from the CCD to the IMCD. For the three segments, the numbers of receptors detected remained constant during the first 2 weeks after birth and increased sharply after 20 days to reach the corresponding adult levels during the fifth week.

Age-related changes in thyroid structure and function in Sprague-Dawley rats.

Investigation of thyroid glands from 500 male and 500 female Sprague-Dawley rats, at time points of 8, 17, 30, 56, and 108 weeks of toxicity studies conducted at the Huntingdon Research Centre between 1981 and 1984, revealed age-related structural and functional changes that have previously not been well documented. The number of ultimobranchial cysts decreased with age, while area(s) of C-cell hyperplasia appeared with age. Beginning at 56 weeks, some of the thyroid follicles were hyperdistended with colloid, had irregular lumens, and were lined by flattened epithelium. These follicles had clumped, granular, and stratified colloid. Follicular tumors were found in 8% of the males and 6% of the females at 108 weeks. There was an increase in absolute thyroid weights (males from 21.8 +/- 4.0 g to 46.5 +/- 19.05 g, females from 17.2 +/- 4.53 g to 41.7 +/- 26.92 g) and body weights (males from 382.0 +/- 70.6 g to 806.0 +/- 120.7 g, females from 220.0 +/- 21.0 g to 495.0 +/- 127.3 g) with age in both sexes, but the relative thyroid weights were not significantly affected. Negative allometry was observed. With an increase in the age of the rats, there was a decrease in the height of the follicular epithelium and an increase in the internal follicular diameter and the total number of follicles. No prediction for sex could be detected. Serum T3 and T4 concentrations were constant until 56 weeks of age, but at 108 weeks, the values were markedly reduced (in males, serum T3 concentration decreased from 91.60 +/- 13.970 ng/100 ml to 32.90 +/- 10.878 ng/100 ml, and in females, from 90.80 +/- 11.338 ng/100 ml to 48.10 +/- 8.875 ng/100 ml; in males, serum T4 concentration decreased from 5.94 +/- 0.679 microgram/100 ml to 3.04 +/- 0.604 microgram/100 ml, and in females, from 4.59 +/- 0.717 microgram/100 ml to 2.77 +/- 0.786 microgram/100 ml). The data suggest that the thyroid function of Sprague-Dawley rats reduces as the rats age.

Lack of proportionality between gene dosage and total muscle protein content in the rat heart.

Counting of isolated cardiomyocytes has demonstrated that their number was 16.8 +/- 0.6 10(6) in both ventricles of weanling rats (28 days after birth), growing in litters of four (fast-growing). In rats growing in litters of 16 (slow-growing), the myocyte number was 11.8 +/- 0.8 10(6). In the control group (8 sucklings per litter), there were 14.2 +/- 10(6) cardiomyocytes. The fast-growing rats had more octoploid cells than slow-growing ones. Considering ploidy and cell number, the total number of myocyte genomes in fast-growing animals was 45% higher than in slow-growing ones. The total content of contractile proteins in fast-growing weanling animals was higher by 28% while sarcoplasmic proteins were 8% higher. This lack of correspondence between the number of myocyte genomes and muscle protein content was even more pronounced at the age of 110 days. The results are compared with the cytophotometric data concerning the lack of correspondence between the total protein content in a myocyte and its DNA amount and chromosome number, i.e., total dosage of the myocyte genes.

Protection by N-acetylcysteine of the histopathological and cytogenetical damage produced by exposure of rats to cigarette smoke.

Adult male Sprague-Dawley rats were exposed whole-body to mainstream cigarette smoke (CS) once daily for 40 consecutive days. Such a treatment resulted in a significant decrease of body weight growth and in intense histopathological changes of terminal airways, including a severe inflammation of bronchial and bronchiolar mucosae, with multiple hyperplastic and metaplastic lesions and foci of micropapillomatous growth as well as emphysema, with extensive disruption of alveolar walls. All histopathological changes were efficiently prevented by the daily administration of the thiol N-acetyl-L-cysteine (NAC) by gavage. Cytological and cytogenetical changes were monitored in bronchoalveolar lavage (BAL) fluid and bone marrow cells of groups of rats killed after 1, 3, 8, 28, or 40 days of treatment. From the first day of exposure, CS significantly enhanced the proportion of polymorphonucleates among BAL cells and the frequency of micronucleated (MN) bone marrow polychromatic erythrocytes. After 8 days, a reduction was observed in the polychromatic/normochromatic erythrocytes ratio and an increase in the frequency of MN pulmonary alveolar macrophages (PAM) was also recorded, followed, after 28 days, by an increase of binucleated PAM. All these alterations immediately reached a plateau and persisted unchanged until the end of the experiment. NAC administration exhibited a significant and considerable protective effect towards the CS-induced alterations of BAL cellularity, the increase of MN PAM and bone marrow cytotoxicity.

A new mathematical model to study bone turnover in growing rats.

A new mathematical model for the study of bone turnover in growing rats was developed. The model predicts a linear relationship between bone mineral content (BMC) and biochemical markers (BMK) of bone turnover assuming that rats are growing, bone turnover is profoundly affected by skeletal maturation, and resorption and formation are physiologically balanced. The model validation was performed by measuring galactosyl-hydroxylysine (GHYL) and hydroxyproline (HYP) in urines. This mathematical evidence supports our proposed use of the specific bone resorption marker GHYL to predict bone mineral content. Further studies on bone turnover will be possible by the application of the same approach.

Effect of antiserum to rat adipocytes on growth and body composition of the rat.

1. Antibody against intact adipocytes was produced in sheep and was capable of binding to intact rat adipocytes using an immunofluorescent assay. An antibody dose level was established and subsequently used in vivo. 2. This study demonstrated inconsistent response of passive immunization procedures with crude antibody against rat adipocytes. Establishment of specific protocols for each antibody preparation would be essential for using this immunological approach in body fat reduction.

Ontogeny of immunosuppressive activity, MHC antigens and leukocytes in the rat testis.

The levels of immunosuppressive activity and the presence of MHC antigens and leukocytes were studied in the immature and the sexually mature rat testis. The immunosuppressive activities were measured from high-molecular weight (greater than 5 kDa) fractions of testis extracts using the protectin bioassay. The presence of MHC antigens and leucocytes was studied using the indirect immunoperoxidase method. In the immature rats, clusters of class I MHC antigen positive cells and a few cells expressing class II MHC antigen were present in the testicular interstitium. In the sexually mature rats, all the cells were MHC I+, and MHC II+ cells were numerous in the testicular interstitium. The seminiferous epithelium was MHC-negative in both the immature and the sexually mature testis. W3/25+ leukocytes were present in the interstitium and the tubular wall in both the immature and the sexually mature rat testis, but not in the seminiferous epithelium at any age. At 20-30 days of age, the testicular extracts were neutral or slightly stimulated 3H-TdR incorporation into peripheral blood lymphocytes, but at 44-60 days of age they inhibited lymphocyte proliferation significantly. In gel filtration, a peak of immunosuppressive activity was observed at approximately 400 kDa (protectin A) in both 20- and 60-days-old rat testes. A smaller peak was present at approximately 200 kDa in both age groups. This study shows that the testicular immunoregulatory microenvironment is different in the immature and the sexually mature rats. This may be important in such age-dependent human diseases as mumps orchitis and the testicular relapses of acute lymphoblastic leukemia.

Postnatal development of the hypothalamic ventromedial nucleus: neurons and synapses.

1. In this report the postnatal differentiation of the hypothalamic ventromedial nucleus (VMN) was studied. The main maturational changes detected at the fine structural level occurred between 10 and 20 days of postnatal life. 2. In 5-day-old rats the majority of neurons was undifferentiated, with rudimentary cytoplasmic organelles. Dendritic profiles presented an empty appearance due to an electron-lucent matrix and scarce content of organelles. 3. At 10 days there was a significant proliferation of cytoplasmic organelles in the perikaryon, mainly of those involved in protein biosynthesis as the rough endoplasmic reticulum (RER) and the Golgi complex. 4. After 20 days of age the VMN neurons acquired the cytological appearance of adult neurons, with well-organized RER, Golgi complexes, and pleomorphic mitochondria. Concurrent with these changes, there was a marked development of other organelles in the neuropil, which was accompanied by an increase in synaptic density and differentiation of their subsynaptic structures.