Electron-microscopic morphometric analysis of mouse liver. II. Effect of ageing and thymus transplantation in old animals

Pieri, Carlo; Giuli, C.; Moro, M. Del; Piantanelli, L.

doi:10.1016/0047-6374(80)90040-8

Cited by 29 publications

(18 citation statements)

References 21 publications

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“…The data of Pieri et al (1975) and David (1985) corroborate the volume density values from these studies. In another study, Pieri et al (1980) observed a gradual increase in the mitochondrial compartment in mice between 2 and 24 months of age.…”

Section: B Animal Age (Months)mentioning

confidence: 94%

Hepatocyte fine structure during maturation and senescence

Schmucker

1990

J. Elec. Microsc. Tech.

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Aging is accompanied by a myriad of changes in cell structure, function, and composition. The fact that much of the information concerning age-related alterations in cellular morphology is qualitative precludes meaningful correlations with biochemical changes in order to enhance data interpretation. The mammalian liver has been subjected to both qualitative and quantitative evaluations of hepatocyte structure as a function of aging, i.e., development, maturation, and senescence. Although these data are characterized by considerable variability and, in some instances, blatant contradictions, there exists sufficient agreement in several parameters to permit a consensus in the inbred rat model. Certainly the volume of individual hepatocytes increases with age, and many of the organelle compartments reflect this change. While old rats exhibit a high incidence of polyploidy, there is no definitive evidence to demonstrate a concomitant increase in the binuclear hepatocyte index. Several specific hepatocellular organelles undergo changes in their relative volume or surface area that appear to correlate with functional alterations. The volume density of the lysosomal compartment enlarges significantly during senescence and is accompanied by increased activities of several constituent hydrolases. The hepatic concentration of smooth-surfaced endoplasmic reticulum declines markedly with aging, as does the yield of liver microsomes and the activities of several microsomal enzymes, e.g., mono-oxygenases and glucose-6-phosphatase. However, the responses of the majority of hepatocyte organelles to aging is varied and inconsistent based on the limited data currently available.

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Section: B Animal Age (Months)mentioning

confidence: 94%

Hepatocyte fine structure during maturation and senescence

Schmucker

1990

J. Elec. Microsc. Tech.

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“…Thus, thymic gland is needed for both development and maintenance of physiological functions of the 13-adrenergic system, but it is also able to recover physiologically relevant age-related alterations. The regulatory influence of thymus has been observed on different tissues, such as submandibular glands, brain cortex and liver, and on different neuronal systems, such as c~-and B-adrenergic ones (21,23,(55)(56)(57)(58). The corrective action of the thymus, in addition, does not seem to act in a nonspecific stimulatory way.…”

Section: Discussionmentioning

confidence: 97%

Insulin receptors in mouse brain: Reversibility of age-related impairments by a thymic extract

Alimazighi

Piantanelli

2000

AGE

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Recently, we have shown that insulin receptors (InsRs) in the brain undergo impairments with aging. Interestingly, age-related alterations of brain InsRs, are not irreparable as thymus grafts are able to recover them. With the present study we verified the possibility that an aqueous extract from calf thymus (TME) can mimic the restoring action of age-related impairments induced by thymus graft. InsR characteristics were assayed in a group of 25 months old BALB/c-nu mice treated with TME: 2μg/g body weight every third day, for total five subcutaneous injections. The last dose was injected the day before animals were killed. Other two groups of young (4 months) and old (25 months) mice received saline solution with the same schedule. A two-sites model analysis of receptor data confirms the age-dependent decrease of InsR number and kd previously observed in the high affinity population. Furthermore, a statistically significant recovery of number impairment is shown in TME-treated animals. On the contrary, the characteristics of the low affinity receptor subset show no statistically significant differences among the three animal models studied. TME induced recovery of the age-related changes found in brain InsRs, together with previously observed regulatory action of the same thymic extract on the adrenergic system, suggest that thymic gland does not necessarily have to mutually interact with other controlling systems for maintaining or recoving homeostasis of the complex neuroendocrine network during development and aging.

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“…In other studies the same group has shown that grafting of neonatal thymus into old mice was able to correct their abnormal serum levels of T 3 and insulin, as well as the decreased response of their submandibular glands to isoproterenol [10]. Neonatal thymus grafting into old mice has also been reported to reverse the agerelated decrease of ß 1 -adrenoceptor density in brain cortex [11] and to correct the age-associated increase in hepatocyte mean nuclear volume [12]. Other workers have reported that the accelerated aging and tumorigenesis of the ovaries that occur in neonatally thymectomized mice can be overcome by the transplant of an intact thymus or injection of T cells [13,14].…”

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confidence: 90%

The Thymus-Pituitary Axis and Its Changes during Aging

Goya

Brown²,

Bolognani³

1999

Neuroimmunomodulation

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The pituitary-thymic axis constitutes a bidirectional circuit where the ascending feedback loop is effected by thymic factors of epithelial origin. The aim of the present article is to review the evidence demonstrating that aging brings about a progressive disruption in the integration of this network. In doing so, we briefly review the experimental evidence supporting the view that immune and neuroendocrine aging are interdependent processes. The advantages and limits of the nude mouse as a model of thymus-dependent accelerated aging is also discussed. Next, we review a number of studies which show that the endocrine thymus produces several bioactive molecules, generally called thymic hormones, which in addition to possessing immunoregulatory properties are also active on nervous and endocrine circuits. In particular, the reported activities of thymosin fraction 5 (TF5), thymosin α-1 and thymosin β-4 on β-endorphin, ACTH, glucocorticoids, LHRH and LH secretion in different animal and cell models are reviewed. The known hypophysiotropic actions of other thymic hormones like thymulin, homeostatic thymus hormone (HTH) and thymus factor are summarized. Aging has a significant impact on pituitary responsiveness to thymic hormones. Thus, it has been reported that TF5 and HTH have thyrotropin-inhibiting activity in young but not in old rats. Furthermore, intravenous administration of HTH was also able to reduce plasma GH and increase corticosterone levels in both young and old rats, although these responses were much weaker in the old animals. Further evidence on this topic is discussed. It is proposed that in addition to its central role in the regulation of the immune function, the thymus gland may extend its influence to nonimmunologic components of the body, including the neuroendocrine system. The early onset of thymus involution might therefore act as a triggering event which would initiate the gradual decline in homeostatic potential that characterizes the aging process.

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Electron-microscopic morphometric analysis of mouse liver. II. Effect of ageing and thymus transplantation in old animals

Cited by 29 publications

References 21 publications

Hepatocyte fine structure during maturation and senescence

Hepatocyte fine structure during maturation and senescence

Insulin receptors in mouse brain: Reversibility of age-related impairments by a thymic extract

The Thymus-Pituitary Axis and Its Changes during Aging

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