Endocrinologia experimentalis 

Abstract: Extirpation of the pineal body of newborn rats was followed by the disorganization of thymic structure, follicular transformation and proliferation, viz. malignant transformation of its epithelial and connective tissue elements. Increase of connective tissue was also observed in the thyroid gland. The follicular cells contained crystal-like bodies and vesicles, whereas in the parafollicular cells the endoplasmic reticulum was increased and light granules appeared.

Abstract: Fifteen seconds after intracarotid injection of either 14C-glucose or tritiated water in adrenalectomized rats, the net uptake of the respective tracer by 18 brain regions and by the anterior pituitary was measured. Corticosterone added to the injection solution (1 or 100 micrograms ml-1; 0.2 ml per animal) caused a dose-dependent decrease of net uptake of 14C-glucose in twelve regions. Compared to the net uptake of tritiated water which was used as a measure of relative blood flow, it suggests that this effect, at least partially, is due to a decreased blood-brain barrier permeability to 14C-glucose. Furthermore, the regional net uptake of 14C-glucose was estimated in rats with different endogenous corticosterone levels but injected with an identical solution in each case. Statistically significant differences could be observed between adrenalectomized and restrained animals in three brain regions.

Abstract: Changes in concentration of insulin, growth hormone (GH) and thyroid stimulating hormone (TSH) in the whey fraction of mammary secretion of women during late pregnancy and lactogenesis were determined by radioimmunoassay. The milk hormone changes were compared to changes in the concentration of milk lactose, glucose and proteins which reflect the transition from colostrum to milk production during lactogenesis. During late pregnancy the average concentrations of insulin, GH and TSH in the colostrum of 2 women were 114.6 microU ml-1, 21.7 microU ml-1 and 14.1 microU ml-1, respectively. The concentrations of these hormones fell from high to low levels between day 1 and day 2 post partum concomitantly with the changes in the concentration of milk lactose, glucose and protein. On day 5 post partum the average milk concentrations of insulin, GH and TSH were 21.0 microU ml-1, 4.0 microU ml-1, and 5.0 microU ml-1, respectively. Similar milk hormone changes occurred in non breast feeding women during the first 11 days post partum. During 2 to 13 months of lactation one woman, the average concentration of milk insulin was 12 microU ml-1. In another woman, from 0 to 22 days after termination of breast feeding, the concentration of insulin increased from 19 to 56 microU ml-1. There were significant positive correlations between hormones and total protein and negative correlations between hormones and lactose, and hormones and glucose in women during lactogenesis and involution. The results showed that the changes in insulin, GH and TSH in milk were closely related to changes in secretory activity and permeability of the breast.

Abstract: Thyroid hormones (TH) in milk can be measured by RIA after prolonged extraction with alkaline ethanol at low temperature. The results of this method agreed with those obtained by gas chromatography-mass spectrometry, though they show the concentrations lower than in most of the already published studies based on radioimmunoassay. The levels of thyroxine (T4) in colostrum and milk in rabbit, cow and women were found to be similar, about 2 nmol l-1, which represented a small fraction of those in blood serum. Triiodothyronine (T3) content approximated one third of that in serum and was about 1.0, 1.8, 0.3 and 0.5 nmol l-1 in the rabbit, pig, human and cow, respectively. Although in a relatively high blood concentration, reverse-T3 does not appear in cow milk, but it passes through the blood/mammary gland barrier into the milk in rabbits in which it appears in a very low concentration. Of TH in milk, T3 may exert some physiological role in offsprings, particularly during the early adaptive postnatal period. Insulin (INS) in human, cow and pig milk was found in concentrations approximate to those in blood serum. They were high at the peri-parturient period and then fell rapidly in the pig and more gradually in the women, to a relatively low and constant levels. Transfer of INS into the mammary gland and milk was positively related to the actual concentrations of this hormone in the blood, in quantities which, following ingestion of milk, might exert some biological action in neonates.