Comparison of Long-Term Perifused Pars intermedia of Anolis carolinensis, Rana pipiens and Hyla chrysoscelis: Their Responses to Dopamine

2004 ◽  
Vol 80 (6) ◽  
pp. 343-354
Author(s):  
Earl B. Barnawell ◽  
Tom W. Bargar
Keyword(s):  
Rana Pipiens ◽  
Anolis Carolinensis ◽  
Pars Intermedia ◽  
Hyla Chrysoscelis ◽  
Responses To Dopamine

Effects of long-term hypoxemia on pituitary-adrenal function in fetal sheep

1996 ◽  
Vol 271 (4) ◽  
pp. E678-E685 ◽  
Author(s):  
J. Murotsuki ◽  
R. Gagnon ◽  
S. G. Matthews ◽  
J. R. Challis
Keyword(s):  
Adrenal Function ◽  
Arterial Oxygen ◽  
Pars Intermedia ◽  
Mrna Levels ◽  
Pars Distalis ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Pomc Mrna ◽  
Pregnant Sheep

To test the hypothesis that long-term hypoxemia causes premature activation of the fetal pituitary-adrenal function, we embolized the fetal side of the placenta in pregnant sheep and examined the changes in concentrations of immunoreactive adrenocorticotropic hormone (irACTH), cortisol, and prostaglandin E2 (PGE2) in fetal plasma, and levels and localization of proopiomelanocortin (POMC) mRNA in the pars distalis and the pars intermedia of the fetal pituitary. Twelve fetal sheep were studied (6 embolized and 6 control) for 21 days between 0.74 and 0.88 of gestation. Daily injections of nonradiolabeled microspheres were given into the fetal abdominal aorta to decrease fetal arterial oxygen content by 40-50% of the preembolization values. In the embolized group, concentrations of irACTH, PGE2, and cortisol in fetal plasma increased gradually and were significantly (P < 0.05) elevated above those of controls after day 10, day 16, and day 20, respectively. POMC mRNA levels in the pars distalis of the fetal pituitary were not different from those of controls but were significantly reduced in the pars intermedia (P < 0.05). We conclude that levels of POMC mRNA in the pars distalis are unchanged during long-term hypoxemia possibly because of negative feedback effects of elevated cortisol on the pituitary gland. During long-term fetal hypoxemia, there is a differential regulation of POMC mRNA expression in the pars distalis and pars intermedia.

The extent of long-term temperature compensation for jumping distance in the frog, Rana pipiens, and the toad, Bufo americanus

1983 ◽  
Vol 61 (6) ◽  
pp. 1284-1287 ◽  
Author(s):  
J. M. Renaud ◽  
E. D. Stevens
Keyword(s):  
Nervous System ◽  
Test Temperature ◽  
Temperature Compensation ◽  
Rana Pipiens ◽  
Acclimation Temperature ◽  
Thermal Compensation ◽  
Muscular System ◽  
Bufo Americanus ◽  
Toad Bufo

The effects of acclimation to either 5 or 25 °C were studied on the longest jumping distances of Rana pipiens and Bufo americanus to estimate their capacity for long-term compensation. Animals were tested randomly at 5, 10, 15, 20, and 25 °C. Both Rana and Bufo jumped further at higher temperatures. For both species, acclimation temperature modified the effect of test temperature. At test temperatures of 20 and 25 °C, frogs acclimated to 25 °C jumped further than those acclimated to 5 °C. There was no evidence for thermal compensation in toads, but half of those acclimated to 25 °C would not jump when tested at 5 °C, whereas only 1 out of 16 cold-acclimated toads did not jump. We suggest that the acclimation effects on the jumping ability of R. pipiens at high temperatures are important in increasing their ability to escape predation and that this effect depends on an effect on the nervous system rather than the muscular system.

Relationship between anoxia exposure and antioxidant status in the frog Rana pipiens

1996 ◽  
Vol 271 (4) ◽  
pp. R918-R925 ◽  
Author(s):  
M. Hermes-Lima ◽  
K. B. Storey
Keyword(s):  
Skeletal Muscle ◽  
Lipid Peroxidation ◽  
Rana Pipiens ◽  
Thiobarbituric Acid ◽  
Leopard Frog ◽  
Antioxidant Defenses ◽  
Glutathione S Transferase ◽  
Glutathione Status ◽  
Organ Specific

The biochemical adaptations of cellular antioxidant defenses that permit anoxia-tolerant animals to deal effectively with rapid and large changes in oxygen availability, and hence oxidative stress, during transitions from anoxia to normoxia provide insights into the strategies of antioxidant defense that could help to minimize reperfusion injuries to mammalian organs after anoxia/ischemia stress. The present study analyzes the effects of 30 h anoxia exposure followed by reoxygenation on the antioxidant defenses (activities of five enzymes, glutathione status) and lipid peroxidation damage to organs of the leopard frog Rana pipiens (5 degrees C-adapted autumn frogs). Exposure to 30 h anoxia resulted in significant increases in the activities of skeletal muscle and heart catalase (by 53 and 47%), heart and brain glutathione peroxidase (by 75 and 30%), and brain glutathione S-transferase (by 66%). In most cases, enzyme activities had returned to the control values after 40 h aerobic recovery. Activities of superoxide dismutase and glutathione reductase were unaltered in all of the organs, and anoxia/recovery had no effect on any of the enzymes in liver. Glutathione equivalents (GSH-eq) were maintained in four organs during anoxia but decreased by 32% in brain during anoxia. Brain GSH-eq had recovered after 90 min reoxygenation, and, in addition, hepatic GSH-eq rose by 71% after 90 min reoxygenation. The ratio of oxidized glutathione to GSH-eq was also affected by anoxia in an organ-specific way. Lipid peroxidation, assessed as the content of thiobarbituric acid-reactive substances (TBARS), was unaltered in skeletal muscle and liver after 30 h anoxia exposure or short (25 and 90 min)- or long-term (40 h) periods of reoxygenation, indicating that cycles of natural and survivable anoxia/reoxygenation occur without significant increase in TBARS in selected organs. Overall, the data demonstrate that elements of the antioxidant system of R. pipiens are induced during anoxia exposures as a possible preparation for dealing with potentially harmful oxygen reperfusion stress.

Control of the pars intermedia of the lizard, Anolis carolinensis

1979 ◽  
Vol 198 (3) ◽  
Author(s):  
Leonard Larsson ◽  
EstebanM. Rodr�guez ◽  
Patrick Meurling
Keyword(s):  
Anolis Carolinensis ◽  
Pars Intermedia
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