[Fluctuations in the level of progesterone in the peripheral blood of nutria during pregnancy]

The fluctuations in the concentrations of progesterone in peripheral blood of three intact coypus and three coypus after natural mating were investigated for the period of four months. Immediately after mating the concentrations of progesterone are low (1.5-2.4 ng.ml-1), the maximum values reach the peak between the 14th and 15th week of gravidity (12.50-20.72 ng.ml-1), whilst there is almost no change in the intact females. On the last days of gravidity the values of progesterone decrease rapidly and they are very low on the day of parturition (1.0-2.5 ng.ml-1). The concentration of progesterone in the blood plasma of intact females in the test period is low (0.09-3.18 ng.ml-1).

Cardiorespiratory responses of the woodchuck and porcupine to CO2 and hypoxia

The burrow-dwelling woodchuck (Marmota monax) (mean body wt. = 4.45 +/- 1 kg) was compared to a similar-sized (5.87 +/- 1.5 kg) but arboreal rodent, the porcupine (Erithrizon dorsatum), in terms of its ventilatory and heart rate responses to hypoxia and hypercapnia, and its blood characteristics. VT, f, T1 and TE were measured by whole-body plethysmography in four awake individuals of each species. The woodchuck has a longer TE/TTOT (0.76 +/- 0.03) than the porcupine (0.61 +/- 0.03). The woodchuck had a higher threshold and significantly smaller slope to its CO2 ventilatory response compared to the porcupine, but showed no difference in its hypoxic ventilatory response. The woodchuck P50 of 27.8 was hardly different from the porcupine value of 30.7, but the Bohr factor, -0.72, was greater than the porcupine's, -0.413. The woodchuck breathing air has PaCO2 = 48 (+/- 2) torr, PaO2 = 72 (+/- 6), pHa = 7.357 (+/- 0.01); the porcupine blood gases are PaCO2 = 34.6 (+/- 2.8), PaO2 = 94.9 (+/- 5), pHa = 7.419 (+/- 0.03), suggesting a difference in PaCO2/pH set points. The woodchuck exhibited no reduction in heart rate with hypoxia, nor did it have the low normoxic heart rate observed in other burrowing mammals.

Regulation of plasma antidiuretic hormone in the dehydrated kangaroo rat (Dipodomys spectabilis M.)

A sensitive and specific radioimmunoassay was used to measure plasma antidiuretic hormone (plasma arginine vasopressin, PAVP) concentrations in a conscious desert-adapted mammal, the banner-tailed kangaroo rat (Dipodomys spectabilis; 131 +/- 2.3 g body mass), during normal hydration and in response to progressive dehydration. Simultaneous measurements of PAVP and plasma osmolality (POSM) in these experiments permitted determination of the hypothalamo-neurohypophyseal system-osmoreceptor set point and sensitivity to extracellular hyperosmolality during dehydration. In normally hydrated kangaroo rats, acclimated to room temperature (20-24 degrees) and fed a dry grain diet, POSM and PAVP averaged 308.6 +/- 0.7 mosmol/kg H2O and 6.0 +/- 0.7 pg/ml (2.2 +/- 0.2 microU/ml), respectively (means +/- SE). In separate groups of animals subjected to 48, 96, 144, or 192 hr of dehydration, POSM and PAVP increased in a parallel linear manner with time to maxima of 329.7 +/- 2.4 mosmol/kg H2O and 68.8 +/- 4.4 pg/ml (24.9 +/- 1.6 microU/ml), respectively, at 192 hr of dehydration. Thus, a highly correlated and significant relationship between POSM and PAVP (r2 = 0.941, P less than 0.001) exists in dehydrated kangaroo rats, quantitatively defined by the linear regression equation PAVP (pg/ml) = 2.99 (POSM - 306.4), with an apparent osmotic threshold for AVP release at a POSM of 306.4 mosmol/kg H2O.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for the presence of alpha 1B-glycoprotein in mammalian sera: immunoblotting studies

1. A monospecific antiserum to pig alpha 1B-glycoprotein (PO2) was produced in rabbits and was used to search for homologues of alpha 1B in sera of 41 mammalian species belonging to seven orders. 2. Specific reactions were detected in the sera of representatives of Insectivora, Primates, Carnivora, Proboscidea, Perissodactyla and Artiodactyla. No cross-reactions were observed in the sera of two species of Rodentia (mouse, rat). 3. Cross-reactions in the sera of Erinaceus europaeus, Homo sapiens and Macaca mulatta were rather weak; this indicates a greater structural difference between the alpha 1 B of Insectivora and Primates and that of the other mammalian orders. 4. Electrophoretic patterns of alpha 1 B were, in most cases, heterogeneous, the most heterogeneous being in ruminants. 5. Evidence was obtained that the alpha 1 B of sheep is identical with the earlier described (Juneja and Gahne (1980) Anim. Blood Grps Biochem. Genet. 11, 81-92.) polymorphic post-transferrin (Ptf).

A natural auto-inhibitory factor of the terminal complement pathway in serum of Ctenodactylus gondi

The serum of Ctenodactylus gondi, a Tunisian rodent, contains a unique inhibitor of the terminal complement pathway. The auto-inhibitor has been partially characterized as a heat-stable euglobulin that is slightly retarded on a DEAE-ion exchange column at pH 7 and elutes as a symmetrical peak on Sephacryl S-300 in the mol. wt region of approximately 200,000. The inhibitor acts by preventing attachment of cytolytic C5b-9 complexes to natural target cells. It does not appear to affect formation and function of C3-convertase, does not exert inhibitory effects at stages later than C5b-7 formation, and also does not prevent formation of SC5b-9 in serum. That the factor prevents attachment of C5b-7/C5b-9 to cells has been demonstrated in hemolysis model systems using sheep EA + human serum, and in the C3-independent reactive lysis system with the use of ELISA methods and quantitative assays with radioiodinated C8. Addition of partially purified inhibitory factor to human sera or to sera of other animal species abolishes the hemolytic activities of these sera. The inhibitory factor of Gondi serum is the first inhibitor of the terminal pathway which has been shown to be capable of preventing cytolysis of cells undergoing complement attack under physiological conditions. The presence of this factor is probably partially responsible for the remarkable susceptibility of C. gondi towards bacterial and parasitic infections.

[Comparative studies on multiple forms of serum cholinesterase in various species]

Multiple forms of serum cholinesterase (ChE) were compared in 8 species by electrophoretic technique and the following characteristics were noted. The first moving fraction markedly hydrolyzed butyrylthiocholine and the activity was not inhibited by 10(-5)M eserine in the serum of some rabbits tested. Electrophoretic patterns of the ChE were obtained by use of two thiocholines as substrate, and the number of fractions against acetylthiocholine were more than against butyrylthiocholine in dogs, miniature pigs, rabbits, and hamsters. The activities of ChE fractions of dogs (C3), miniature pigs (C1, C2), rabbits (C1), and hamsters (C3) were inhibited by 6.1 X 10(-2)M caffein but not by 10(-4)M ethopropazine, which suggests that the fractions are all true-ChE.

Haematological correlates of burrowing in Ctenomys

Haematological parameters related to O2 transport and regulation of acid-base equilibrium were determined for two species of Ctenomys. The oxygen capacity values of Ctenomys blood are similar to those of other fossorial mammals. Ctenomys blood has almost half the number of red blood cells of Rattus blood but the amount of Hb in each blood cell is 2-2.5 times higher. Blood pH is within typical mammalian values. Concentration of inorganic phosphate is higher in Ctenomys than in rats while bicarbonate and protein values are within typical mammalian range.

Circulating progesterone, progesterone-binding proteins and oestradiol-17 beta concentrations in the pregnant Cape porcupine, Hystrix africaeaustralis

Circulating concentrations of progesterone, progesterone-binding plasma proteins (PBPP) and oestradiol-17 beta in pregnant porcupines remained relatively low until Days 25-30 post coitum. Progesterone values peaked (102-180 ng/ml; N = 3) 42-60 days post coitum and the rapid increase in oestradiol-17 beta concentrations approximated that of progesterone with peak values (170-210 pg/ml) being attained 60-85 days post coitum. The pattern of PBPP synthesis, as suggested by circulating concentrations, was closely related to that of plasma progesterone, with values remaining low (less than 20 pmol/ml) until Day 31 post coitum, reaching peak levels at Days 50-56 and Days 73-77 post coitum. The production of PBPP during pregnancy is, as in related New World hystricomorph species, considered to be a mechanism which facilitates a reduction in the rate of progesterone metabolism during pregnancy.

Hemoglobin and oxygen: different affinities in two species of rodents (Mus musculus and Pitymys duodecimcostatus)

Five different hemoglobins have been demonstrated by polyacrylamide-gel disk electrophoresis in the species Mus musculus. Oxygen affinities of hemoglobin (P50) from Mus musculus and Pitymys duodecimcostatus hemolysates were determined at pH 7.4 and 37 degrees C. Values obtained for delta log P50/delta pH in hemolysates from both species point out a more pronounced Bohr effect in Pitymys duodecimcostatus.

[Blood glucose levels of Holochilus brasiliensis nanus Thomas, 1897, natural host of Schistosoma mansoni in lower Amazonia]

Roedores silvestres, nascidos em biotério, descendentes de Holochilus b. nanus, capturados na região da Baixada Maranhense, localizada na Pré-Amazônia, foram infectados experimentalmente com Schistosoma mansoni, procedente da mesma Região, com o objetivo de verificar a influência da infecção sobre os níveis glicêmicos. Um grupo de roedores não infectados tiveram, também, seus níveis glicêmicos determinados, para o conhecimento da concentração normal de glicose. O estudo procedeu distinguindo os animais, tanto os normais quanto os infectados, por sexo, regime alimentar e idade de infecção. A quantificação da glicose sérica foi feita pelo método da Orto-Toluidina, após sangrias semanais pelo plexo oftálmico, sempre no mesmo horário. Os resultados mostraram que ocorreu elevação de pesos corporais de todos os animais normais, durante suas maturações, ao passo que, os animais infectados, tiveram seus pesos em decréscimo, durante a evolução da infecção. Os níveis glicêmicos estudados nos animais normais mostraram que as fêmeas possuem nível mais baixo e estável do que os machos, independente de terem sido alimentados ou não. Os animais infectados aos 30 dias de vida tiveram seus níveis glicêmicos em declínio à proporção que a infecção evoluía, provavelmente, devido ao acometimento dos órgãos, como baço, fígado e pâncreas; enquanto que, os animais infectados aos 40 dias de vida, tiveram seus níveis de glicose, durante as 8 semanas de infecção, sem diferença significativa entre eles. O número de vermes adultos recuperados nos animais infectados com 30 dias de vida foi maior do que o número encontrado nos roedores do outro grupo. Os dados informaram, também, que, a idade ideal para a infecção deste novo modelo experimental, deva ser a de 30 dias de vida, semelhante a outros, como camundongos.

Circulating progesterone and oestradiol-17 beta concentrations in cyclic Cape porcupines, Hystrix africaeaustralis

The general pattern of steroid secretion during the 30-day oestrous cycle of the Cape porcupine is that of a surge (25-176 pg/ml) in oestradiol-17 beta secretion at the time of perforation of the vaginal closure membrane, followed by an increase in progesterone concentrations, the latter attaining peak values (mean 5.9 +/- 2.1 ng/ml) 8-19 days (13.8 +/- 2.8 days) after vaginal opening. Copulation occurred after the oestradiol-17 beta surge and the length of the luteal phase of the cycle varied from 21 to 35 days (29.3 +/- 4.7 days), this representing 93% of the length of the cycle. Perforation of the vaginal closure membrane was not always accompanied by an increase in oestradiol-17 beta levels and some instances (19%) of vaginal opening were not followed by an increase in progesterone secretion. The hormonal characteristics of the oestrous cycle of females housed with vasectomized males were similar to those of females housed with intact males.

Customized vascular catheters for rodents

Custom arterial and venous catheters were made for rodents from polyurethane tubing. The low thrombogenicity and toxicity index, chemical stability and resiliency of polyurethane made this tubing an ideal catheter material. The tubing is shaped using peanut oil heated to 160 degrees C. Sealing these catheters is accomplished simply by heating the tube end with a hot object and pinching it between the fingers. Chronic catheter patency was maintained using Burr's solution (9:1 mixture of glycerine and heparin). No flushing was necessary.

[Variations in peripheral blood cells levels found in Holochilus brasiliensis nanus Thomas, 1897, infected with Trypanosoma cruzi Sambon, 1907, from pre-Amazonia]

Foram constituídos quatro grupos de roedores silvestres para a contagem de células sangüíneas periféricas, da seguinte forma: Grupo I - formado de animais normais, nascidos em biotério, com 30 dias de vida; Grupo II - formado de animais que foram capturados no campo e considerados não infectados com S. mansoni, após ovohelmintoscopia das fezes, realizada durante 30 dias de observação; Grupo III - animáis capturados no campo, nautralmente infectados com o esquistossomo, e o Grupo IV - de animais nascidos em biotério, com 30 dias de vida, e infectados com 150 cercárias de S. mansoni, oriundas da Região da Baixada Maranhense. Semanalmente, a partir da data da infecção, estes animais foram sangrados e tiveram suas células sangüíneas periféricas contadas global e especificamente. Os resultados mostraram que o número de hemácias e leucócitos por mm³ não variou nos animais normais, tanto de campo como de biotério. No grupo de animais experimentalmente infectados, foi observado decréscimo do número de hemácias à proporção que a infecção evoluia. Comportamento oposto foi verificado com os leucócitos. Elevados níveis de eosinófilos só foram observados nos animais com infecção natural. Estes resultados foram discutidos com dados da literatura e considerados importantes para complementar as informações sobre este hospedeiro natural do trematódeo, oferecido como modelo experimental do verme, e para sua própria história natural.

Mole rat hemoglobin: primary structure and evolutionary aspects in a second karyotype of Spalax ehrenbergi, Rodentia, (2n = 52)

The hemoglobins of the four karyotypes of Spalax ehrenbergi (2n = 52, 54, 58, 60) did not show any differences in their electrophoretic pattern and in high performance liquid chromatography. The complete amino-acid sequence of mole rat hemoglobin (Spalax ehrenbergi), chromosome species 2n = 52, is presented. It was elucidated by automatic Edman degradation of the chains, the tryptic peptides, and the C-terminal peptide obtained by acid hydrolysis of the Asp-Pro bond in beta-chains. The alpha- and beta-chains are identical with those of the chromosome species 2n = 60. A comparison of the hemoglobins of mole rat, mouse, and other rodents shows homology but no indication of adaptation to subterranean life. In all probability alpha 11(A9)Arg and alpha 120(H3)Gly, unique in mole rat among all mammalian hemoglobins, are not involved in high oxygen affinity. The construction of a phylogenetic tree by the maximum parsimony method, based on hemoglobin sequences, made it possible to show that Rodentia originated as a monophyletic clade, and to find the phylogenetic relationship of Spalacidae to other Rodentia (Mus, Rattus, Ondatra, Mesocricetus, Citellus, and Cavia). Among all rodents the slowest rate of nucleotide replacements occurred in the lineage to Spalax (20%) and the fastest in the lineage to Cavia (59%).

Seasonal variations in plasma luteinizing hormone and testosterone levels in the European badger Meles meles L

Although active spermatogenesis occurs throughout the year in the male European badger Meles meles L., seasonal fluctuations of testicular activity were observed. The present study compared the pattern of luteinizing hormone (LH) and testosterone (T) secretions throughout the annual cycle. LH secretion was investigated by means of a heterologous radioimmunoassay using anti-ovine LH beta antiserum and canine reference standard. Seasonal and nycthemeral changes in LH and T secretions were observed. During the year a period of maximal values for both hormones is well correlated with the breeding. Moreover, episodic LH releases occurs during the period of minimal testosterone values, indicating resumption of hypothalamo-pituitary activity well before the breeding period.

Measurement of plasma LH concentrations in aged male rodents by a radioimmunoassay and a radioreceptor assay

Circulating plasma concentrations of LH from young mature (3-4 months old), middle-aged (15-18 months old) and aged (31-32 months old) male C57BL/6 mice, Syrian hamsters (3-4, 19-20 and 24-25 months old), Fischer 344 rats (3-4, 18-19 and 28-29 months old), Chinese hamsters (3-4, 19-20 and 29-30 months old) and Mongolian gerbils (3-4 and 19-22 months old) were analysed using a radioimmunoassay (RIA) and a radioreceptor assay (RRA). Male rats exhibited the greatest changes with advancing age: the oldest rats had an almost undetectable quantity of plasma LH, as measured by both assays. In contrast, the oldest male Syrian hamsters had significantly higher levels of LH than did younger animals. A significant decrease occurred in the amounts of LH detectable by RRA in middle-aged Chinese hamsters which was not evident with the RIA. There were no statistically significant differences in LH levels of C57BL/6 mice and gerbils with increasing age. The mean RRA:RIA ratios indicated that age-related differences in LH concentrations resulted from physiological changes in the secretion or the metabolic clearance of LH and not from changes in the biological potency of LH.

Annual plasma testosterone and thyroxine cycles in relation to hibernation in the edible dormouse Glis glis

Twelve male edible dormice, captured in the autumn of 1979, were studied for 2 years under natural lighting in an animal enclosure with permanently open windows, at Montpellier, in Southern France (latitude 43 degrees 50' N). Ambient temperature fluctuated annually between +4 and 27 degrees, and the photoperiod between 10L:14D and 16L:8D. Another group of 26 animals, captured in the autumn of 1980, was observed under the same conditions for 1 year. Body weight and plasma testosterone and thyroxine concentrations were measured at monthly intervals under standardized conditions. Hibernation generally extended from October to February but lasted till May in a few cases, and the critical temperature for dormancy varied between 13 and 16 degrees in November and 23 degrees in May. Body weight fluctuated annually according to a biphasic pattern, with two maxima, respectively, in spring and autumn (prehibernation), and two minima, in summer and winter. However, plasma testosterone and thyroxine concentrations displayed clearly monophasic annual cycles, closely correlated, both to each other and to the ambient temperature and photoperiod. Both the testosterone and thyroxine cycles culminated in June-July. Interestingly, the annual ascending phase for both hormonal cycles never preceded the terminal arousal of the animal. Further, whatever the season, 30 degrees was clearly the critical minimal body temperature required for a seasonal increase to occur in plasma testosterone. These annual cycles are discussed in the light of the data acquired recently for hibernators other than the dormouse.

Adaptations to hypercapnic conditions in the nutria (Myocastor coypus)--in vivo and in vitro CO2 titration curves

Arterial blood acid-base status of unanesthetized, unrestrained nutria was studied during exposure to 5, 10 and 14.5% CO2 for 6 hr. Control values, pH = 7.426 +/- 0.037, PaCo2 = 36.5 +/- 3.1 mmHg and [HCO-3] = 24.3 +/- 2.5 mM/1 (n = 24), are within the normal range reported for other mammals. Values after 6 hr of exposure to 10% CO2 were: pH = 7.355 +/- 0.043, PaCO2 = 71.0 +/- 3.6 mmHg and [HCO-3] = 38.0 +/- 4.1 mM/l (n = 5). Arterial blood buffer slopes, obtained from the in vitro titration curve, did not show any pattern of adaptation to hypercapnia. Whole body buffer slopes, calculated from the in vivo CO2 titration curve, showed significantly higher values for the nutria than for the rat, dog and man, under comparable conditions [beta(delta HCO-3/delta pH)] = 57.0 slykes for nutria, 32.6 for rat and 11.8 for man. delta H+/delta PaCO2 = 0.38. mM/l/mmHg for nutria, 0.55 for rat and 0.76 for man. The results suggest that the nutria possesses an efficient metabolic mechanism for regulation of pH level during exposure to hypercapnic conditions.

Luteinizing hormone levels in aged female laboratory rodents as measured by a radioimmunoassay and a radioreceptor assay

Plasma levels of LH were measured in young sexually mature (2- to 5-month-old) and aged (13- to 20-month-old) female C57BL/6 mice, Syrian hamsters and Wistar rats using a radioimmunoassay (RIA) and a radioreceptor assay (RRA). There were no statistically significant differences when comparing data from the two assays when examining young oestrous and dioestrous mice. Aged oestrous and dioestrous mice exhibited significantly higher levels of LH as measured by RIA than by RRA. Levels of LH analysed by RIA were also higher in aged mice compared with those in younger mice. Comparing LH hamsters produced similar results. In contrasts, aged pseudopregnant rats exhibited significantly lower levels of plasma LH than younger dioestrous females and there were no differences in RIA and RRA values. There were also no differences when comparing data from the two assays in younger rats. The mean (+/- S.E.M.) RRA: RIA ratios of 0.96 +/- 0.05 (oestrous) and 0.96 +/- 0.04 (dioestrous) for younger mice and 0.92 +/- 0.08 for younger hamsters were significantly higher than the ratios of 0.66 +/- 0.05, 0.72 +/-0.05 and 0.71 +/- 0.05 respectively of their aged counterparts. The mean RRA: RIA ratios in the two age groups of rats were almost identical (0.79 +/- 0.05 and 0.80 +/- 0.10). These studies suggested that a portion of the higher LH levels detectable by RIA in some aged female rodents results from qualitative changes in the LH molecule.

Interaction of amphipathic drugs with erythrocytes from various species

Changes in morphology of human erythrocytes exposed to certain amphipathic drugs can be predicted by the bilayer couple hypothesis as proposed by Sheetz and Singer (Proc Natl Acad Sci USA 71:4456-4461, 1975). When we tested that hypothesis, using erythrocytes from other mammals, we found that most but not all, underwent the predicted changes. Both camel and llama erythrocytes showed minimal morphologic changes when exposed to anionic and cationic phenothiazines. The spicules formed by anionic drug in different species were numerically related to cell sizes. We conclude that structural rigidity of the erythrocyte membrane can alter the response predicted by the bilayer couple hypothesis.

Receptor in group C and G streptococci detects albumin structures present in mammalian species

The presence of albumin structures with the capacity to bind to a surface receptor in group C and G streptococci was studied in serum samples from 45 mammalian species representing 15 different orders, using an inhibition assay. The ability of animal sera to inhibit the uptake of radiolabeled human serum albumin by the streptococci indicated the presence of such albumin structures. Positive reactions were found in species of most orders tested, with Marsupialia as a notable exception. All Carnivora sera tested were strongly positive. In some orders such as Artiodactyla both positive and negative species were identified. Serum samples from 62 bird species representing 15 orders and from 5 fish species were also tested in the inhibition assay. None of these serum samples was capable of inhibiting the uptake of human serum albumin by streptococci. Some differences were also noted in the results obtained with group C and G streptococci from human and bovine sources, respectively, indicating the presence of two types of receptors. The present studies suggest a phylogenetic origin of albumin structures with affinity for the streptococcal receptor to a period after the divergence of Marsupialia from the other mammalian orders.

A new method for the determination of blood ethanol levels in rodents

A procedure is described for the estimation of ethanol in blood of rodents. The procedure is based on the same principle as the breath analyzer method used with human subjects. Using a specifically designed mask, samples of rebreathed air are collected under equilibrium conditions. These are injected directly into gas chromatograph for the quantitation of ethanol. We determined the conversion factor for calculating blood ethanol levels from those determined in breath to be 1:2857. The method was validated by comparing blood (from the jugular vein) and breath values obtained on the same animal after the administration of various doses of ethanol either intraperitoneally or intragastrically.

[The red blood picture in male nutria in the post-natal period]

Blood was sampled by heart puncture from healthy male coypus of ten age categories (from 1 to 300 days). The basic haematological values of the red blood picture were determined in these samples. including the erythrocyte count, haemoglobin content, haematocrit reading, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, and mean corpuscular volume. The summarized mathematico-statistical characteristics were calculated from the values obtained in each group and the significance of differences was determined by the analysis of variance at significance levels of P = 0.01 and P = 0.05.