Alterations in Thyroid Physiology During Pneumococcal Septicemia in the Rat1

Abstract

A QABSTRACT. The impact of acute infection on iodine concentration was decreased. Kidney thyroid physiology was investigated in rats inradioactivity in the T3 and T 4 groups was unfccted with a type-specific pneumococcus. Inchanged by infection. Although infection altered fected rats showed a lower thyroidal 13I uptake bowel motility, with a resultant delay in the apCc than healthy controls at all time periods studied. pearance of radioactivity in the colon of rata Unlike in the rat, thyroidal 131 uptake curves in given 13I-T, or 1'I-T 4 , total body disappearance the infected and healthy mouse and guinea pig of the labeled hormones, followed over a period of vwere superimposable. Thyroidal I' release in the several days, was not appreciably altered. The infected rat was significantly delayed when comdecrease in thyroidal function during infection q• pared to similar release curves in uninfected appeared to be related to an intrinsic defect animals. Although the thyroid of the infected rat within the gland itself. This concept was supSresponded to a physiologic dose of exogenous ported by a marked fall in the PBI and circulat-TSH, both its uptake and release of I'I showed ing unbound thyroxine. The decrease in serum an absolute reduction. S.rum TSH levels mea-13I-T 4 ti, an increase in the per cent of unbound sured by bio-assay were not altered during infecthyroxine, and an increase in Ts resin uptake were tion. The disappearance time of MI-T 4 from postulated to be the result of a decrease in T, blood of infected rats was significantly shorter binding by serum proteins during infection. The than that of healthy controls, while disappearance failure of serum TSH levels to change appeared times of blood 'M'I-Ts were unchanged. Organ to be related to a decreased pituitary response to radioactivity was measured following serial alterations in circulating unbound thyroxine. In sacrifice after the administration of 1'I-T 4 or spite of these changes, no specific alteration in "3I-T3 to healthy and infected rats. In the T 4 thyroid physiology could be demonstrated that group radioactivity in livers from infected rats would differentiate infection from other nonwas consistently lower than in h,.althy animals, specific stresses in the rat. (Endocrinology 79: In both the infected T, and T 4 groups, thyroidal 511, 1966) T HE RESPONSE of the thyroid gland oides immitis (2). This report was followed in generalized infection has been the by a comprehensive paper by Reichlin and subject of only a few reports compared to Glaser (3), who infected rats by an intratrathe volume of literature on intrinsic dis-cheal injection of streptococci and found eases of the thyroid. Although diminished the thyroidal release of 13'I to be delayed. basal metabolic rates were reported as They postulated that reduced TSH output, early as 1926 in children and adults follow-associated with lowered food intake during ing pneumonococcal pneumonia (1), no infection, might contribute to the reduction basic research into the mechanisms of thy-of thyr...

Alterations in thyroid iodine release and the peripheral metabolism of thyroxine during acute falciparum malaria in man

“…In earlier studies, an increase of the fractional rate of To turnover [(k)] has been observed during infectious illness in rats (2), monkeys (5), and man (1,3,4), although Wiswell and Coronho noted no change in Ts turnover in volunteers given typhoid fever (21). A decrease in T4 turnover has been observed only after surgical stress (22,23).…”

“…DISCUSSION Studies of thyroid function during infection in animals and man have yielded a variety of results. The prepon--derance of data, however, suggests that peripheral thyroxine (T4) turnover is increased (1)(2)(3)(4)(5), and that thy- roid function is generally depressed initially, and then often rebounds during recovery from the infectious illness (6)(7)(8)(9). The great majority of these earlier studies depended either upon the use of epithyroid counting to estimate the rate of release of glandular hormonal iodine, or upon measurement of the concentration of serum PB"1I with time after the injection of labeled T4, in order to assess peripheral To metabolism.…”

“…The great majority of studies of thyroid function during naturally acquired or experimentally induced infections in man and animals have suggested that the fractional rate of peripheral turnover [(k)]' of thyroxine (T4) is accelerated under such conditions (1)(2)(3)(4)(5). Those studies which have attempted to assess the rate of thyroidal iodine release during acute illness, either by direct serial epithyroid count rates after 'I administration, or by changes in the concentration of stable To in serum.…”

Alterations in thyroid hormone economy during acute infection with Diplococcus pneumoniae in the rhesus monkey

“…Leukocytes isolated from blood obtained Received for publication 9 July 1970 and in revised form 7 November 1970. ronine (TB) in several animal species, the results of such studies tend to be conflicting, appearing to vary with the nature of the species examined. In the rat, for example, acute streptococcal and pneumococcal infections appear to result in a depression of thyroid function (1,2), whereas in man data obtained after treatment of acute pneumococcal pneumonia had been instituted suggest that an increase in thyroid function might accompany this type of stress (3).…”

Military Strategies for Sustainment of Nutrition and Immune Function in the Field

“…Additionally, the depressed plasma concentrations of thyroid hormones fail to stimulate the secretion of thyroid-stimulating hormone (TSH), thus indicating an impairment in the pituitary-thyroid feedback system Shambaugh-Beisel, 1966). These abnormalities are the result of cytokineinduced alterations at all levels of this system .…”