Metabolic, ventilatory, and hygric physiology of a South American marsupial, the long-furred woolly mouse opossum

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metabolic, ventilatory, and hygric physiology of the gracile mouse opossum (Gracilinanus agilis)

We present the first complete study of basic laboratory-measured physiological variables (metabolism, thermoregulation, evaporative water loss, and ventilation) for a South American marsupial, the gracile mouse opossum (Gracilinanus agilis). Body temperature (Tb) was thermolabile below thermoneutrality (Tb = 33.5°C), but a substantial gradient between Tb and ambient temperature (Ta) was sustained even at Ta = 12°C (Tb = 30.6°C). Basal metabolic rate of 1.00 mL O2 g-1 h-1 at Ta = 30°C conformed to the general allometric relationship for marsupials, as did wet thermal conductance (5.7 mL O2 g-1 h-1 °C-1). Respiratory rate, tidal volume, and minute volume at thermoneutrality matched metabolic demand such that O2 extraction was 12.4%, and ventilation increased in proportion to metabolic rate at low T a. Ventilatory accommodation of increased metabolic rate at low Ta was by an increase in respiratory rate rather than by tidal volume or O2 extraction. Evaporative water loss at the lower limit of thermoneutrality conformed to that of other marsupials. Relative water economy was negative at thermoneutrality but positive below Ta = 12°C. Interestingly, the Neotropical gracile mouse opossums have a more positive water economy at low Ta than an Australian arid-zone marsupial, perhaps reflecting seasonal variation in water availability for the mouse opossum. Torpor occurred at low Ta, with spontaneous arousal when . T b > 20°C. Torpor resulted in absolute energy and water savings but lower relative water economy. We found no evidence that gracile mouse opossums differ physiologically from other marsupials, despite their Neotropical distribution, sympatry with placental mammals, and long period of separation from Australian marsupials. © 2009 by The University of Chicago. All rights reserved.

Pleistocene mammals from the southern Brazilian continental shelf

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of placental glycogen storage in mild diabetic rats

Purpose: To evaluate the placental glycogen storage and fetal development in the pregnancy of neonatally streptozocin-induced diabetic rats and to establish relation with glycemia and insulin levels. Methods: At the birth day, 147 female rats were randomly distributed in two experimental groups: 1) Non-diabetic Group (Control, n=45) - received the vehicle; 2) Diabetic Group (STZ, n=102) received 100 mg streptozocin/kg in neonatal period. At day 0 of pregnancy, adult female rats were included in the control group when presented glycemia below 120 mg/dL and, in the group STZ with glycemia between 120 and 300 mg/dL. At day 21 of pregnancy, blood samples were collected for glycemia and insulin determination, and placentas withdrawn for placental glycogen determination. The newborns (NB) were classified in small (SGA), appropriate (AGA) and large (LGA) for gestational age. Results: Rats STZ presented higher glycemia at days 0 and 14 of pregnancy. At end of pregnancy, rats STZ showed higher proportion of NB SGA and LGA; reduced rate of NB AGA and unaltered glycemia, insulin and placental glycogen determinations. Conclusion: Mild diabetes altered the maternal glycemia in the early pregnancy, impairing future fetal development, but it caused no alteration on insulin and placental glycogen determination, confirming that this glycemic intensity was insufficient to change glycogen metabolism.

Plasma concentrations and placental immunostaining of interleukin-10 and tumor necrosis factor-alpha as predictors of alterations in the embryo-fetal organism and the placental development of diabetic rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphometric study of placental villi and vessels in women with mild hyperglycemia or gestational or overt diabetes

In this study, morphometric measures of placental terminal villi and villous vessels were compared in overt, as well as gestational diabetes mellitus, and mild hyperglycemia diagnosed by oral 100 g glucose tolerance test (100 g-OGTT) and glucose profile (GP). At delivery (gestational age >= 34 weeks) a total of 207 placentas were assigned to a control group (n = 56) or to one of three groups complicated by mild hyperglycemia (n = 5 1), gestational diabetes (n = 59) and overt diabetes (n = 4 1). Placenta samples were randomly selected for blind morphometric assessment with an image analyser. Morphometric measures obtained included area and number of terminal villi and their respective villous vessels. Statistical analyses were performed using the chi-square test, ANOVA and stepwise regression (p <= 0.05). Glycemic means were 86.2 mg/dL in controls, 98.9 mg/dL in mild hyperglycemia, 114.1 mg/dL in gestational diabetes and 122.1 mg/dL in overt diabetes. Our results show that abnormal maternal glycemic levels may change the placental morphometric characteristics related to materno-fetal exchanges. (C) 2007 Elsevier B.V.. All rights reserved.

Changes in apoptosis and Bcl-2 expression in human hyperglycemic, term placental trophoblast

Apoptosis and its associated regulatory mechanisms are physiological events crucial to the maintenance of placental homeostasis; imbalance of these processes, however, such as occurs under various pathological conditions, may compromise placenta function and, consequently, pregnancy success. Increased apoptosis occurs in the placentas of pregnant women with several developmental disabilities, while increased Bcl-2 expression is generally associated with pregnancy-associated tumors. Herein, we tested the hypothesis that apoptosis-associated disturbs might be involved in the placental physiopathology subjected to different maternal hyperglycemic conditions.Thus, in the present study we investigated and compared the incidence of apoptosis using TUNEL reaction and Bcl-2 expression, in term-placentas of normoglycemic, diabetic and daily hyperglycemic patients. Tissue samples were collected from 37 placentas, being 15 from healthy mothers with normally delivered healthy babies, and 22 from mothers with glucose disturbances. From these latter 22 patients, 10 showed maternal daily hyperglycemia and 12 were clinically diabetics. Both Bcl-2 expression and apoptotic DNA fragmentation were established and quantified in the trophoblasts of healthy mothers. Compared to these reference values, a higher apoptosis index and lower Bcl-2 expression were disclosed in the placentas of the diabetic women, while in the daily hyperglycemic group, values were intermediate between the diabetic and normoglycemic patients. The TUNEL/Bcl-2 index ratio in the placentas varied from 0.02 to 0.09 for pregnant normoglycemic and diabetic women, respectively, revealing a predominance of apoptosis in the diabetic group. Our findings suggest that hyperglycemia may be a key factor evoking apoptosis in the placental trophoblast, and therefore, is relevant to diabetic placenta function. (c) 2006 Elsevier B.V.. All rights reserved.

BLOOD and PLACENTAL OXIDATIVE STRESS ASSESSMENT IN RATS WITH MILD DIABETES

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)