Despite a number of studies on noise-induced health effects, it is still unclear to what extent different neuroendocrine pathways are affected by noise exposure. Male Wistar rats were housed in sound-attenuated rooms isolated for noise from outside. Three groups of chronically cannulated rats were exposed to either background noise (±64 dB) only or irregular experimental white noise (90 dB, 2-22 kHz). Two protocols, with approximately the same total amount of noise but with different densities, were used: protocol N1 (180 min random noise per day for 18 days) or protocol N2 (540 min random noise per day for 8 days). Basal levels of circulating hormones (ACTH, corticosterone, prolactin and catecholamines) and plasma glucose were measured. In control animals, no significant changes in any of these parameters were observed over 18 days. Except for plasma prolactin, N1 did not induce a significant elevation in basal hormonal levels. N2 however induced significant elevation in basal prolactin, corticosterone and noradrenaline levels. At the end of the exposure period, all animals were subjected to a novel heterotypic stressor (restraint stress) to monitor differences in neuroendocrine activation (ACTH, corticosterone and prolactin). Compared to nonexposed control animals, N1 animals showed a normal ACTH and an enhanced corticosterone response, whereas N2 animals showed an increased ACTH but a normal corticosterone response. The prolactin response of both Nl and N2 animals was significantly decreased. Adrenal cell suspension experiments revealed that in noise-exposed rats both basal- and ACTH-stimulated corticosterone production were significantly increased as compared to control animals. These results indicate that chronic noise exposure at mild intensities induces subtle but significant changes in hormonal regulation.
Marehesani syndrome consists essentially of shortness of stature, spherophakia and other eye abnormalities and brachydactyly. It is probably an inherited disease of unknown etiology manifesting itself in organs of mesodermal origin.Investigations of a patient with the full picture of the syndrome revealed normal growth hormone levels following insulin and glucagon stimulation as well as normal thyroid function. Karyotypy was also normal. Intelligence was average for the patient's age.
Experimental studies in our laboratory suggest a possible role for a milk-related infectious agent in the etiology of medial aortic lesions in rabbits. The "~pontaneous,'~ nonlipid, medial lesions found in rabbit aortas have been described previously ( 1 ) . Fragmentation and disruption of the elastic lamina with accumulation of acid mucopolysaccharide is observed confined to the inner onehalf to one-third of the media. Frequently the fragmented portions of the elastic fibers are calcified. The relatively high incidence of these lesions in a large sample of rabbits of different breeds, sexes, ages and geographical sources has also been described ( 2 ) . The results of that study suggested the need for a more extensive analysis of familial factors in the etiology of these lesions. The establishment of families that are either "resistant" or "nonresistant" to the lesions, based on incidence at 8 weeks of age, was achieved through a careful selection program.Rabbits from these families were then used to demonstrate the existence of a milk factor related to the incidence of the medial lesion ( 3 ) . Newborn pups were exchanged, between mothers of unrelated familial lines, for foster nursing. Aortas were examined for lesions when the babies were 8 weeks old. Lesions were found in the aortas of rabbits that had been left with their own mothers of the nonresistant families and also in aortas of rabbits foster-nursed by these does. No lesions were found in aortas of rabbits nursed by resistant does regardless of whether the pups were their own or had been born to does of the nonresistant families. The study reported here was undertaken to test the hypothesis that an infectious agent is related to the incidence of this lesion. Tetracycline was selected as the test drug because of its effec-tiveness against a broad spectrum of microbial organisms.Methods. Does of nonresistant familial strains were bred to bucks of their own strain. All does used had previously delivered at least two litters. Tetracycline (66 mg/kg of body wt) was administered orally to the does from approximately 5 days prepartum until 5 days postparum. A portion of each litter was also treated with the drug at the same dose level for the first 5 days postpartum. Aortas were examined for incidence and severity of medial aortic lesions when the pups were 8 weeks of age. The appearance of a single, grossly visible, lesion was sufficient to categorize an aorta as being involved. The severity of the lesion was based on the area of the arch and ascending aorta involved with the lesion. The only procedural change made for the second phase of this study was the elimination of the treatment of the does. As a control, two resistant does were also tested. One litter from each doe was used in the first phase and only one litter was used in the second phase. No lesions were found in any of these 14 rabbits.Results and Discussion. The results of this study are outhed in Table I. Previous controls represent 132 pups born, under normal conditions, to the same does used i...
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