Effect of stress on the acetylcholinesterase activity of the hypothalamus-pituitary-adrenal axis in the rat

Acetylcholinesterase (AchE, EC 3.1.1.7) activity was determined in cerebral cortex, hypothalamus, adenohypophysis and adrenal gland in response to acute and chronic stress. Chronic exposure of animals to cold stress (at 4 degrees C for 7 days) resulted in significant decline of AchE activity in all tissues studied. Similar results were obtained when animals were exposed to acute immobilization and cold stress (at 4 degrees C) simultaneously. In another experiment, animals were treated with 2 mg/kg of corticosterone prior to AchE determination. Corticosterone administration resulted in a significant decline in AchE activity of the cortex, the hypothalamus and the adrenal but failed to affect the adenohypophysis AchE level. Exposing adrenalectomized animals to acute stress resulted in no significant changes in the cortex and the hypothalamus but caused a significant decline in AchE of the adenohypophysis. It was concluded from this study that corticosterone might mediate the stress effect on AchE activity.     

Trigger properties of gonadotropic hormones and oocyte factors in connection with the germinal epithelium of the rat testis]

In order to reveal possible stimulation of growth of the germinal epithelium of the rat's injured testicle the animals were injected follicle-stimulating and luteinizing hormones and their mixture as well as homogenate of fertilized egg-cells during two weeks. Changes of neurosecretion in large-cell nuclei of the anterior hypothalamus, cellular set in the adenohypophysis and the condition of the germinal epithelium in the gonad under study were investigated. Identical phenomena of reduction (having quantitative distinctions) took place due to effects of exogeneous honadotropins in neurosecretory nuclei and the adenohypophysis. In testicular tubules there occurred pronounced proliferation of the germinal epithelium, but spermatogenesis was absent. Egg-cell homogenate failed to cause changes in neurosecretion and adenohypophysis but resulted in completing the developmental cycle of the germinal epithelium with mature spermatozoa. The effect of gonadotropins upon the system hypothalamus-hypophysis is explained by feed-back mechanism, and the absence of spermatogenesis--by the lack of androgens. The rsults of egg-cell homogenate effects should be associated with local stimulating effects of DNA of the dividing egg-cell.     

Morphological and functional changes in several endocrine glands induced by hypothyroidism in the rat

The effect of hypothyroidism upon the morphology and the function of several endocrine glands was studied in radiothyroidectomized male rats. It was found that T3, T4, insulin, prolactin and corticosterone levels were significantly lower in hypothyroid rats. TSH levels were significantly higher in these animals while no changes were depicted in testosterone levels. The administration of T4 drew back to normal range the above-mentioned altered serum hormone levels. The studies performed with light microscopy revealed alterations only in the TSH secretory cells of the adenohypophysis. Conversely, when using the electron microscope to study the different endocrine glands, clear alterations were depicted in the TSH and prolactin secretory cells of the adenohypophysis, as well as in the pancreatic B cells and the cells of the zona fasciculata of the adrenal cortex. No abnormal changes were demonstrable at the level of the seminiferous tubules of the testis. All the above morphological changes were corrected by the administration of T4 to hypothyroid rats. These results suggest that the hypothyroid state is a complex hormonal dysfunction rather than a single hormonal defect. The secretory alterations are accompanied by fine cellular alterations in the corresponding glands.     

Distribution of 3H-thymidine in the postnatal hypophysis of the C57BL mouse

The distribution of cells labelled with 3H-thymidine was determined autoradiographically in the adenohypophysis and neurohypophysis of the C57BL mouse during postnatal phases ranging from the newborn to 24 days of age, as well as in the adult. In the newborn, labelled cells are scarce in the neurohypophysis but common in the adenohypophysis. The neurohypophysis shows a surge in labelling at 5-9 days, with a sharp decline thereafter. In the adenohypophysis, labelled nuclei are scarce in the pars tuberalis after 19 days, whereas the pars intermedia and pars distalis continue to show labelled cells. In the pars distalis, at all phases, label occurs in the marginal cells along the hypophysial cleft as well as in deeper-lying cells representing follicular cells. In the adult, follicular cells are more commonly labelled relative to other cells of the hypophysis.     

The emergence and maintenance of interdyad differences in the mother-infant relationships of rhesus macaques: A correlational study

The role of the mother in promoting infant independence, reflected in the time spent out of contact with her by the infant, was addressed with a simple correlational approach to scores of time out of contact (Off) and frequencies of acts of maternal rejection and restriction through the infants’ first 16 weeks of life. Correlations of the extents of age changes from week to week were also examined. Infants differed consistently in the times they spent off from their fourth through their eighth weeks, while rates of maternal restriction and rejection were consistent from week 4 until at least week 8 in both sexes and from week 2 in females. The correlations were consistent with the view that time off was set at its week-4 and possibly later levels by maternal rejection, while some further changes in time off, resulting in a loss of consistency from week to week, reflected the extents to which mothers of daughters decreased their restrictive behavior. Weeks in which individual differences in maternal restriction and rejection were correlated with differences in time spent off were generally weeks in which changes in group means of these mean measures were correlated. In daughters, age changes of individual dyad’s scores of time off and maternal rejection were correlated between week 2 and week 4, supporting the view that in these early weeks age changes and individual differences were produced by the same processes. Findings from comparative and experimental studies, and the limitations of correlational approaches now available, are discussed.     

Chromogranin A proteolysis to generate beta-granin and WE-14 in the adenohypophysis during the rat oestrous cycle

Immunohistochemical analysis of the male and female rat adenohypophysis revealed that chromogranin A (CgA), beta-granin and WE-14 immunostaining was localised to follicle stimulating hormone (FSH) producing cells, while luteinizing hormone (LH) producing cells exhibited chromogranin A and beta-granin immunostaining. The intensity of chromogranin A, beta-granin and WE-14 immunostaining exhibited variation during the oestrous cycle; weak immunostaining was observed during proestrous and oestrous, corresponding with the lowest cellular concentration of luteinizing and follicle stimulating hormone. Chromogranin A and beta-granin immunostaining were similar in both the male and female (at dioestrous), however, a larger number of more intense WE-14 immunopositive cells were evident in the male adenohypophysis relative to the female at any stage of the cycle. The tissue and plasma concentrations of beta-granin and WE-14 immunoreactivity fluctuated throughout the oestrous cycle. Maximum and minimum beta-granin and WE-14 tissue concentration counterpoised the latent maximum and minimum plasma concentration. Chromatographic analysis of adenohypophysis extracts revealed the degree of chromogranin A proteolysis throughout the oestrous cycle; in contrast, plasma profiles consistently possessed a large chromogranin A-like immunoreactant. This data suggests that chromogranin A biosynthesis, proteolysis and the secretion of its derived peptides parallels that of the gonadotroph hormones throughout the oestrous cycle.     

Morphofunctional features of the secretory cells of the adenohypophysis and adrenal glands of the rat during aging

Karyometric and electron microscopic investigation has been performed in the adenohypophyseal secretory cells, in the cortex and medulla of the adrenal glands in mature (6 months) and ageing (25-26 months) white male rats. The diameter of the corticotropic cell nuclei of the adenohypophysis significantly increases with age. In the secretory cells of the adrenal cortex and medulla no important changes in their parameters are revealed. With age destructive changes of the ultrastructures are manifested variously in different types of the secretory cells in the endocrinic glands studied. In the corticotropic, somatotropic, thyreotropic cells of the adenohypophysis, in spongiocytes of the adrenal cortex, compensatory ultrastructural rearrangements develop; they are aimed to preserve functional activity of the cells mentioned. No age changes are revealed in ultrastructure of chromaffin cells of the adrenal medulla.     

An input of heterochronies to the formation of interspecific differences in wood mice, Sylvaemus (Rodentia)

Difference in adult size and body shape among the closely related species is the result of diversification in morphogenetic processes. We examined age variation in various external and craniometric characters of four Sylvaemus species from Ukrane fauna, S. uralensis, S. arianus, S. sylvaticus, and S. tauricus, using cross-sectional techniques. The intensive growth period occurred to be different in various species. Rapid growth of S. tauricus continues during all life span, while in other species growth rate becomes slower at different stages. This peculiarity of S. tauricus may be the result of prolonged and more intensive production of somatotropin by adenohypophysis. Side effects of adenohypophysis activation are resulted from changes in S. tauricus skull shape and more intensive pigmentation in comparison with three other species. Prolongation of growth could be developmental mechanism for size increasing in evolution of S. tauricus. The independence of body size and pigmentation is principally the same at interspecific and intraspecific level.     

The differentiation of prolactin cells in an organ culture of chick embryo adenohypophysis

We have studied differentiation of prolactin cells in explants of cephalic and caudal parts of Rathke's pouch of 4.5 day and 5.5 day old chick embryos after their incubation in vitro lasting for 7-8 days. Indirect immunofluorescence using an antiserum against bovine prolactin was used to detect prolactin cells in the cultures. Differentiation of prolactin cells was detected regularly in explants of the cephalic lobe of the adenohypophysis anlage in 5.5 day old embryos; under certain growth conditions prolactin cells were found in explants of the same lobe in 4.5 day old embryos. Prolactin cells were either absent or found in small numbers in cultures of the caudal part of adenohypophysis of 5.5 day old embryos. Our results provide evidence for the appearance of the committed precursors of prolactin cells in the Rathke's pouch at late stages of its formation and for their regional localization in the cephalic part of the anlage. This localization is in correspondence with the distribution of differentiated cells of this type in definitive adenohypophysis.     

The distribution of competence for adenohypophysis development in the ectoderm of chick embryos

The ability of various zones of the cephalic and trunk ectoderm to differentiate into adenohypophysis after the contact with the bottom of the prosencephalon was studied in tissue culture of chick embryos as the stage of 10-13 somites. Stomodeal presumptive lens ectoderm and lateral cephalic ectoderms were shown to be competent for development into adenohypophysis. In all cases adenohypophyseal cords were formed in the zones of ectoderm contact with the brain. The cords contained antigens A-2, A-3 specific for chicken adenohypophysis as well as ACTH and beta-lopotropin. Trunk ectoderm proved to be incapable to differentiate into adenohypophysis.     

Effect of thermal stress and water deprivation on the acetylcholinesterase activity of the pig brain and hypophyses

The effects of direct exposure of boars to thermal stress for 1 h daily for 5 days and to acute water deprivation for 24 or 48 h were studied on the acetylcholinesterase (AChE) activity of porcine brain and hypophysial regions. Mean ambient temperatures, respiratory rates and rectal temperatures in the open were significantly higher than inside the pen. Heat stress induced a rise in AChE activities in the pons, cerebellum, amygdala, hippocampus, hypothalamus, mid-brain and medulla oblongata. However, no significant changes were observed in the cerebral cortex, adenohypophysis and neurohypophysis. Water deprivation significantly (P<0.05) depressed AChE activity to varying extents depending on the duration of water restriction. Thus AChE activity in the amygdala was depressed by water deprivation for 24 h but partially restored at 48 h. The pons and medulla oblongata were comparable to the amygdala in this respect. The adenohypophysis and neurohypophysis were relatively unaffected.     

Ultrastructural changes in the adenohypophysis, adrenal gland activity, and desynchronization of the oestrous cycle following unpredictable stress in the rat

An ultrastructural study of the adenohypophysis, after exposure of female Wistar rats to a signalled unpredictable 5- and 15-day stress regimen, is described. Cellular activity of the adenohypophysis correlated well with the circulating levels of corticosterone. Intense secretory activity was observed in all tropic cell types at 5 and 15 days although the observed differences generally were greater in the 5-day stressed group. It was observed that the oestrous cycles of 40 and 100% of the rats became desynchronized over the 5- and 15-day stress period respectively.     

The determination of the cytodifferentiation of the adenohypophysis in embryonic development

This is a review of the literature and author's own data on determination of various cell types of adenohypophysis during embryonic development. Recent studies using techniques of organ culture and immunohistochemistry have established the time of determination of glandular cells of adenohypophysis. It has been shown in rat embryos that the direction of differentiation of all major cell types of adenohypophysis is programmed late during the development of the epithelial anlage of this organ. Similar data as concerns somatotropic and prolactin cells have been obtained on chick embryos. Chick embryos possess regional type of determination of prolactin and somatotropin-containing cells in the anlage in correspondence with their location in definitive adenohypophysis.     

Postnatal changes in testicular development and androgen receptors immunolocalization in D'Man ram lambs

The purpose of this study was to characterize testicular development in D'Man ram lambs, focusing primarily on androgen receptors (ARs) immunolocalization in the adenohypophysis and testis that is not still known in the D'Man ram lamb. Lambs (n = 12) were divided into four groups (three lambs per group). Adenohypophysis and testis were fixed and paraffin embedded; cross-section (3 μm) were stained and evaluated with immunohistochemistry. Testis weight increased at a greater rate between two and five months after birth, which was associated with remarkable changes in testicular histology, including significant increases in the diameter of seminiferous tubules. Spermatogenesis started between three and five months after birth; lumen and elongated spermatids were observed for the first time in three and four months-old animals respectively. ARs detected with immunohistochemistry were located in the nuclei and cytoplasm of adenohypophysis cells, and only in nuclei of testis cells (Leydig, Sertoli, peritubular myoid and germ cells).     

Immunochemical identification of the growth hormone and prolactin in the hypophyseal polypeptide spectrum of chickens

Forty-eight fractions of polypeptides including 39 fractions with a molecular weight of 14-95 kD were identified in chick adenohypophysis by sodium dodecyl sulphate electrophoresis in 10-20% gradient polyacrylamide gel slabs. The immunochemical identification of the polypeptides was performed with the aid of the electroblotting of proteins and antisera to human STH, to bovine prolactin, and to the tissue-specific antigen A-1 of chick adenohypophysis. Antisera to human STH and to antigen A-1 reacted with the same major polypeptide fraction, m.w. 26 kD, characteristic of the caudal lobe of the adenohypophysis. Immunoreactive prolactin was present in chick adenohypophysis in the form of a polypeptide fraction with a molecular weight of 25 kD and in the form of two minor fractions of polypeptides with molecular weights of 27 and 28 kD. The data obtained indicate the identity of the adenohypophyseal tissue-specific antigen A-1 to chick STH.     

Facts and hypotheses concerning the function of non-granulated cells in the adenohypophysis of vertebrates

Electron microscopic examination of the non-granulated cells of the adenohypophysis of several species has evidenced a unity of structure amongst vertebrates. Efforts to correlate structure and function have been made, but they have often been hampered by the scarcity or absence of direct experimental methods for the investigation of their function. Yet often the evidence in favor of a given role has been circumstantial, relying on coincidences between changes in the secretory activity of the gland and changes in the ultrastructure of the non-granulated cells or in colloid production. At the present time, the prevailing hypothesis is that, in addition to a possible role in mechanical support within the gland, the non-granulated cells seem to be important with respect to the secretory process of the endocrine cells and/or to the metabolism of the adenohypophysis.     

Tissue specific antigen of the caudal lobe of the chicken adenohypophysis]

The tissue-specific water-soluble antigen of the chick pituitary gland was revealed by immunochemical analysis. The content of this antigen was found to be predominant in the caudal lobe of the adenohypophysis. The antigen was found from the 13th day of embryogenesis by immunoelectrophoresis and immunofluorescence. Two kinds of the antigen (with high and low relative electrophoretic mobility) were discovered in the chick adenohypophysis. A conclusion was drawn that the adenohypophysis cells differed by the differentiation level.     

Effects of essential fatty acids deficiency in milk diets on the development of germ-free and conventional rats

Conditions allowing physiological development were determined in infant rats delivered by Caesarian section on the 22nd day of gestation and fed, from birth onwards, on various diets by stomach tube. Two new diets were prepared--K 50 A (11.7% fat, 7.7% protein) and LNaH (7.6% protein, 12% fat). The sole difference between the two diets is in the essential fatty acid (EFA) content, which is 42.6% in diet K 50 A, but only 0.7% in diet LNaH. Animals reared on the LNaH diet displayed slower growth and delayed development of the adenohypophysis and the thymus. Degenerative changes (intracytoplasmic vacuolation) were found in the somatotropin-producing cells of the adenohypophysis. The serum prolactin concentration of animals fed on the LNaH diet was lower than in the suckled controls and in animals given the K 50 A diet. The damaging effect of the LNaH diet was particularly marked on the first five days after birth, indicating that this is a critical period in the development of the newborn rat. The histological structure of the adenohypophysis and thymus of animals reared on the K 50 A diet was the same as in the suckled controls.     

Changes in dehydrogenase glutamate in the rat brain caused by thyroid hormone deficiency

The dependent GDH-NADPH activity in adenohypophysis and other cerebral areas, has been studied in hypothyroid rats, in which hypothyroidism has been induced surgically. After thyroidectomy a decrease of GDH activity in limbic system (amygdala, septum and hippocampus), and an increase of this enzyme in cortex and hypothalamus have been found, with no changes in adenohypophysis. The alterations of GDH activity, induced by thyroidectomy, have been corrected, although not uniformly in the different brain areas after L-T3 treatment.