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Cellular and molecular interactions of thymus with endocrine organs and nervous system.
- Kinoshita Y, Hato F
Cell Mol Biol (Noisy-le-grand). 2001 Feb;47(1):103-17.
T-cell
ontogenesis has been disclosed to depend on the interactions of thymus
with endocrine glands
and nervous system
as follows: i/ Thymic
deprivation
not only impaired the immunological
development but also brought about the dysgenesis
of pituitary
anterior lobe. Conversely, hypophysectomy
resulted in thymus
atrophy
with the disturbed immune
responses. ii/ Binding
of pituitary
acidophilic cell hormones
to their receptors on thymus
epithelial cells
(TECs) augmented the release
of thymic
hormonal
peptides
(THPs) in vitro.
iii/ Elevation of blood glucocorticoid
level after stress caused atrophy
of thymus
cortex
through double positive thymocyte
apoptosis.
Morpho-molecular alterations of cytoplasm
preceded nuclear
damage in the apoptotic thymocytes. iv/ Administration
of thymosin
to the streptozotocin-induced diabetic
mice repressed mononuclear cell infiltration
to the pancreatic
islets. v/ Autonomic
nerve fibers
innervate
thymic
parenchyma.
Binding
of acetylcholines (Achs) to Ach receptors on TECs enhanced protein
synthetic activity which seemed to connect with THP production. vi/ Thymectomy
not only depressed
the immune
responses but also accelerated the reduction of leaming and memory ability with aging.
The operation appears to disturb the brain adrenoceptor functions and to suppress the regulatory roles of hypothalamus
to other nervous tissues. vii/ Several kinds of THPs, separated from the culture supernatant
of TEC line by high performance liquid chromatography,
showed a favorable effect on the thymocytes at different stage of differentiation and maturation. viii/ Thymosin,
thymulin and THPs were capable of proliferating and differentiating thymocytes in vitro.
However, the administration
of each thymic
product to the thymus-deprived animals could not restore
from their "wasting
disease". Since TECs are composed of a heterogeneous
population, it would be one of essential ways for isolating "true thymus
hormone"
(TTH) to use the material which consists of functionally homogeneous
subset of TECs. ix/ An additional grafting of pituitary gland
to the thymus-grafted nude mice
improved the disturbed T-cell
ontogeny.
Accordingly, the administration
of "TTH" and pituitary
acidophilic cell hormones
might be more hopeful procedure
for rescuing the thymus-deprived animals from "wasting
disease".
This abstract at PubMed.