Old rats are unresponsive to the behavioral effects of adrenocorticotropin

Neuroendocrine and behavioral effects following an acute or chronic treatment with the calcium antagonist, flunarizine, have been studied in young and old rats. Both in young and old rats, acute administration of flunarizine (2 mg/kg) failed to modify plasma prolactin (PRL) levels, as measured at 8.00 a.m., 4.00 p.m. and 12.00 p.m. A chronic treatment with flunarizine (0.5 mg/kg/day, for 20 days) in young rats was followed by a relevant, albeit statistically not significant, increase in plasma PRL levels, as measured at 8.00 a.m. and 4.00 p.m., and by a significant decrease at 12.00 p.m. A shift of nocturnal peak of plasma PRL levels from 12.00 p.m. to 4.00 a.m. was observed in these animals. A chronic treatment with flunarizine in old rats was followed by a significant increase in plasma PRL levels, as measured at 12.00 p.m. The acquisition of active avoidance behavior was studied in a shuttle-box test. Acute administration of flunarizine failed to change the performance of young and old rats in acquiring the behavioral response, as measured by the total number of conditioned avoidance responses (CARs) and the percentage of learners. When flunarizine was administered chronically, a decrease in CARs and learners was observed both in young and old rats. This was accompanied by a significant increase in the percentage of animals that froze during the acquisition session. No significant effect was found in young and old rats tested in a “despair” test after a chronic treatment with flunarizine.

Download Full-text

Endotoxin Alteration of the Mucopolysaccharide Blood Vessel Coating in Rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050755 ◽

1974 ◽

Vol 32 ◽

pp. 148-149

Author(s):

D. E. Philpott ◽

A. Takahashi

Keyword(s):

Skeletal Muscle ◽

Endothelial Cells ◽

Salivary Gland ◽

Carotid Artery ◽

Basement Membrane ◽

Coronary Vessels ◽

Ruthenium Red ◽

E Coli ◽

Old Rats ◽

The Brain

Two month, eight month and two year old rats were treated with 10 or 20 mg/kg of E. Coli endotoxin I. P. The eight month old rats proved most resistant to the endotoxin. During fixation the aorta, carotid artery, basil arartery of the brain, coronary vessels of the heart, inner surfaces of the heart chambers, heart and skeletal muscle, lung, liver, kidney, spleen, brain, retina, trachae, intestine, salivary gland, adrenal gland and gingiva were treated with ruthenium red or alcian blue to preserve the mucopolysaccharide (MPS) coating. Five, 8 and 24 hrs of endotoxin treatment produced increasingly marked capillary damage, disappearance of the MPS coating, edema, destruction of endothelial cells and damage to the basement membrane in the liver, kidney and lung.

Download Full-text

Light and electron microscopic investigation of adenohypophyses of germfree, food-restricted, and germfree-food restricted aging, male lobund-wistar rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103826 ◽

1988 ◽

Vol 46 ◽

pp. 352-353

Author(s):

G. Ilse ◽

K. Kovacs ◽

N. Ryan ◽

T. Sano ◽

L. Stefaneanu ◽

...

Keyword(s):

Wistar Rats ◽

Microscopic Investigation ◽

Electron Microscopic Investigation ◽

Aging Male ◽

Sprague Dawley ◽

Electron Microscopic ◽

Sprague Dawley Rats ◽

Old Rats ◽

Ad Libitum ◽

Microscopic Findings

Germfree state and food restriction have been shown to increase life span and delay tumor occurrence in rats. We report here the histologic, immunocytochemical and electron microscopic findings of adenohypophyses of aging, male Lobund-Wistar rats raised at Lobund Laboratories. In our previous study, the morphologic changes in the adenohypophyses of old rats have been extensively investigated by histology, immunocytochemistry and electron microscopy. Lactotroph adenomas were frequent in Long-Evans and Sprague-Dawley rats, whereas gonadotroph adenomas were frequent in Sprague-Dawley and Wistar rats.Male Lobund-Wistar rats were divided into four groups: 1) conventional, which were raised under normal non-germfree environment and received food ad libitum; 2) germfree-food ad libitum; 3) conventional environment-food restricted and 4) germfree-food restricted. The adenohypophyses were removed from 6-month-, 18-month- and 30-month-old rats. For light microscopy, adenohypophyses were fixed in formalin and embedded in paraffin.

Download Full-text