Heavy metals and the mammalian thymus: in vivo and in vitro investigations.

This experiment was performed to investigate changes in the thymus of Wistar-strain male rats administered cadmium chloride (CdCl2), mercuric chloride (HgCl2), and lead chloride (PbCl2) salts. The study involved measurement of: 1) deoxyribonucleic acid (DNA) content; 2) ascorbic acid (vitamin C) content; 3) incorporation of 3h-thymidine during in-vitro investigation; and 4) histological and morphological changes. It was shown in investigations on DNA content that administration of heavy metal salts caused an average 76% decrease in DNA content compared to the control. Moreover, in the thymus of experimental animals, an average 69% decrease in vitamin C content was recorded. In in vitro cultures, heavy metal salts decreased the incorporation of 3H-thymidine in thymic cells.

Effect of lithium salts on the microstructure of the thymus and on vitamin C content in some lymphatic organs, the liver and suprarenal glands in F1 mouse crosses (CBA x C57BL).

The administration of lithium chloride (LiCl) to mice by intraperitoneal injection caused involution in the thymus, both in the cortex and medulla. Lithium also considerably decreased vitamin C (ascorbic acid) content in all of the organs that were studied: thymus, lymph nodes, spleen, suprarenal glands, and liver.

Physiological dependency between the hypothalamus and the thymus of Wistar rats. IV. Organotypic culture of the thymus in the presence of hypophyseal hormones, vasopressin, and oxytocin.

The experiments were carried out with the cultured thymic glands of the 7 d old rats. 3H-thymidine incorporation rate, histological alterations and the lipid level within the entire gland were studied. In cultures supplemented with 200 ng of vasopressin per ml of medium, the amount of the incorporated 3H-thymidine was lower than in the control cultures, whereas in cultures to which higher quantities of the same hormone (10 micrograms/ml) were added a reverse effect was observed and the difference was statistically significant as compared with the control cultures (p less than 0.001). Addition of oxytocin (0.01 units/ml of the medium) to the culture brought about a slight increase in the incorporation of 3H-thymidine. Histological and histochemical studies showed that the involution of the thymic tissue was least pronounced in the cultures supplemented with vasopressin in amount of 10 micrograms per ml of the medium.

Physiological dependency between the hypothalamus and the thymus of Wistar rats. V. 3H-thymidine incorporation by the organotypic culture of thymus in the presence of serotonin.

Thymic glands of 7 d old Wistar rats were used for the experiments. 3H-thymidine incorporation after different culture periods and the histological alterations were studied. The obtained results show that the addition of serotonin (5-HT) at the concentration of 2 micrograms and 10 micrograms per ml of the culture medium decreases 3H-thymidine incorporation by DNA-synthesizing thymic cells. Serial histological sections prepared after 48 h of the culture revealed a lowered number of thymocytes which were regularly distributed over the entire area of the thymus, leading to the disappearance of a boundary between the cortical and medullary parts of the organ. The histochemical studies showed that in the thymic glands cultured in the presence of serotonin appeared numerous mast cells located mainly in the central parts of the gland.

[Physiological dependency between the hypothalamus and the thymus in Wistar rats. III. Hypothalamic cells cultured in vitro in the presence of Thymus Factor X (TFX) and fresh thymus filtered homogenate].

The studies were carried out on the hypothalamic cells cultured in vitro in the presence of low-molecular proteins (constituting the control): the thymic hormone, known as Thymus Factor X [TFX]; or fresh thymus filtered homogenate prepared from the glands collected from 1 h or 7 d old rats. All the cultures were supplemented with 3H-thymidine. The experiments demonstrated that TFX in when added to the culture caused a decrease 3H-thymidine synthesis in comparison to the control. In other cultures, which were enriched with the fresh thymus filtrated homogenate, especially from 7 d old rats, a high level of thymidine synthesis in the cellular nuclei was observed.

The physiological relationship between the hypothalamus and thymus of Wistar rats. I. Some morphological and microstructural changes in the hypothalamus in newborn rats following thymectomy.

The investigations were carried out on male Wistar rats. 12 h after birth newborn rats were subjected to thymectomy, and subsequently observed for the period of 8 weeks. The studies of the rat hypothalamus revealed that supraoptic nuclei (NSO) contained numerous cells which dyed dark. The cells were deprived of nuclei, or else they were shrunk. Similar cells were encountered in the medial eminence (EM). Measurements of cellular nuclei within NSO and NPV demonstrated that their size diminished following thymectomy what after t-test calculations yielded a statistically significant value.

Neurosecretory and microstructural changes in the hypothalamus of rats following administration of lithium chloride and 3H-thymidin.

Adult male rats were intraperitoneally administered aqueous solution of lithium chloride (LiCl). Studies, including neurosecretory and microstructural changes within particular neurocytes in supraoptic (NSO) and paraventricular nuclei (NPV) were performed on hypothalamic sections. In the experimental rats the administered LiCl increased the level of GOMORI-positive neurosecretory material both in supraoptic and paraventricular nuclei. Great amounts of the neurosecretory material were markedly conspicuous in the above areas after 20 days of LiCl administration. Investigations carried out on cellular nuclei of particular neurocytes showed a significant enlargement of the nuclei, and statistical calculations revealed that, in comparison with the basic control, the difference was essentially significant (p less than 0.001). 3H-thymidin administration to the rats which had previously been on LiCl for 20 days demonstrated also that within supraoptic nuclei the incorporation of the isotope in cellular nuclei took a faster course than in control animals.

Physiological dependency between the hypothalamus and the thymus in Wistar rats. II. The neurosecretion level and microstructural changes following para-chlorophenylalanine administration. The differences in DL-5-hydroxy G-3H tryptophane incorporation in the hypothalamus of normal and thymectomized rats.

The experiments were carried out on male Wistar rats, both normal and thymectomized in which the thymus was excised in 12th h of life. 8 weeks later, the animals were administered parachlorophenylalanine [PCPA], i.e. a compound inhibiting tryptophane hydroxylase, in the amount of 200 mg/kg of body weight. The studied hypothalamus preparations, i.e. supraoptical [NSO] and paraventricular nuclei [NPV] revealed an increased level of Gomori-positive neurosecretory material in thymectomized rats when compared to control animals. It was observed that the former rodents manifested an elevated incorporation of the isotope, i.e. DL-5-Hydroxy [G-3H] Tryptophane. The calculations performed by the use of the Gosset's t-test ("Student's") showed that the difference was statistically significant (p less than 0.001).

Changes within the thymus gland as induced by high doses of hydrocortisone--histological and histochemical aspects.

The investigations were carried out on mature male Wistar rats. Hydrocortisone was administered intramuscularly for the period of 10 or 20 days. Histological findings showed that within the thymus gland the compact and fat connective tissue was proliferated, including both cortical and medullar zones. In the medullar part large vesicular forms filled with a substance of a basic character could be observed. Studying the thymus sections from the histochemical point of view, one could note numerous cells filled up with the Gomori-positive substance. The cells, mainly grouping in the cortical zone were often of a giant size.