Purinergic signalling in endocrine organs

There is widespread involvement of purinergic signalling in endocrine biology. Pituitary cells express P1, P2X and P2Y receptor subtypes to mediate hormone release. Adenosine 5′-triphosphate (ATP) regulates insulin release in the pancreas and is involved in the secretion of thyroid hormones. ATP plays a major role in the synthesis, storage and release of catecholamines from the adrenal gland. In the ovary purinoceptors mediate gonadotrophin-induced progesterone secretion, while in the testes, both Sertoli and Leydig cells express purinoceptors that mediate secretion of oestradiol and testosterone, respectively. ATP released as a cotransmitter with noradrenaline is involved in activities of the pineal gland and in the neuroendocrine control of the thymus. In the hypothalamus, ATP and adenosine stimulate or modulate the release of luteinising hormone-releasing hormone, as well as arginine-vasopressin and oxytocin. Functionally active P2X and P2Y receptors have been identified on human placental syncytiotrophoblast cells and on neuroendocrine cells in the lung, skin, prostate and intestine. Adipocytes have been recognised recently to have endocrine function involving purinoceptors.     

Purification of proctolin-binding proteins from the foregut of the insect Blaberus craniifer.

A membrane protein that specifically binds the insect neuropeptide proctolin was purified using standard chromatography from cockroach foregut membranes. Proctolin-binding sites were efficiently solubilized with either the nonionic detergent digitonin or the zwitterionic detergent Chaps, as indicated by the specific binding of 3H-proctolin to solubilized samples. A solubilized sample obtained from 1600 foregut membranes was subjected to a five-step chromatographic purification including chromatofocusing, anion-exchange and size-exclusion chromatographies. The final size-exclusion separation resulted in the isolation of approximately 100 pmol of purified proctolin-binding proteins, eluting as a single peak at approximately 74 kDa. Analysis of the purified sample using SDS/PAGE and silver staining showed two bands at 80 kDa and 76 kDa. Densitometric analysis of the gel indicated that each band contained approximately 7-8 microg of protein, suggesting that one band corresponds to the proctolin-binding activity. Proctolin-binding proteins were thus purified 1800-fold using standard chromatography.     

Distribution of the lithium ion in endocrine organs of the rat

Lithium ions accumulated consistently in the pituitary and thyroid of rats at concentrations significantly greater than in plasma. There was also a significant, although lower, accumulation of Li⁺ in the adrenal gland. No accumulation of lithium ion was noted in the testis or in the ovary. The possible significance of these findings with regard to some of the side effects of lithium carbonate treatment is discussed.     

3H-tyrosin incorporation by foregut entoderm, as an additional proof of extra-glandular presence of endocrine ptoencies.

Atopic transplants of embryonic rat larynx, trachea, and oesophagus incorporated 3H-tyrosine selectively and of similar degree to like transplants of thyroid. Further to similar observations with radioiodine, this finding supports the conclusion that primordial endocrinic potencies are retained, and can be activated, in a broader range of foregut derivatives than implied from the actual functional manifestations.     

Cellular and molecular interactions of thymus with endocrine organs and nervous system.

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".     

Epidermal cyst originating from the preauricular sinus

Epidermal cysts are the benign tumors which are found in various regions. We experienced a rare case in which the preauricular sinus was the origin of the epidermal cyst.     

Seasonal changes in endocrine organs of the male common frog,Rana temporaria

Summary The annual cycle of the five morphological cell types in the pars distalis of the adenohypophysis of male common frogs,Rana temporaria, was studied in variously stained sections of the pituitary, collected at monthly intervals. All cell types showed a maximal development at the end of hibernation, a strong extrusion of secretory granules in the breeding season, and a more gradual release during later spring and early summer. A minimal development occurred in mid-summer, and a restoration followed in autumn and the hibernation period. During the phase of extrusion production was low, and vice-versa. These seasonal changes correspond with those of the testes and interrenal tissue of the same animals as well as with those of the thyroids and other endocrine tissues, and seems to be an important part of the biphasic annual life cycle of the species.The authors gratefully acknowledge the patient and skilful technical assistance of MissFemmy Brands. They thank Mr.H. van Kooten for making the photographs.     

Permeability of biological barriers of the endocrine organs to serum proteins in guinea pigs

The experiments on guinea-pigs have established that the vessels of endocrine organs are permeable for autogenic and heterogeneous serum proteins. Parenchymatous cells of these organs play the role of barriers for serum proteins. These parenchymatous cells are responsible for the type of barrier in each endocrine organ.