The physiological effects of extracts of the pituitary body

Regulatory mechanism of the arginine vasopressin-enhanced green fluorescent protein fusion gene expression in acute and chronic stress

Various kinds of stress cause neuroendocrine responses such as corticotropin-releasing hormone (CRH) or arginine vasopressin (AVP) release from parvocellular division of the paraventricular nucleus (PVN) and activation of the hypothalamo-pituitary adrenal (HPA) axis. We examined the effects of acute and chronic stress on the expression of the AVP-enhanced green fluorescent protein (eGFP) fusion gene in the hypothalamus, using chronic salt loading as an osmotic stimulation, intraperitoneal administration of lipopolysaccharide (LPS) as acute inflammatory stress and adjuvant arthritis (AA) as chronic inflammatory/nociceptive stress. Salt loading caused a marked increase in the eGFP gene expression and eGFP fluorescence in the supraoptic nucleus, magnocellular division of the PVN and internal layer of the median eminence (ME). Administration of LPS caused increased fluorescence in parvocellular division of the PVN and external layer of the ME. AA rats revealed an increased expression of the eGFP gene and eGFP fluorescence in both magnocellular and parvocellular divisions of the PVN and both internal and external layers of the ME. On the other hand, the levels of the CRH gene expression in parvocellular division of the PVN were significantly decreased as AA developed, though plasma concentrations of corticosterone were significantly increased. These results indicate that AVP-eGFP transgenic rats enable the detection of changes in AVP expression more easily than by using procedures such as immunohistochemistry. We propose that AVP-eGFP transgenic rats represent a useful animal model for further understanding of the physiology of AVP expression in the hypothalamo-pituitary system under various physiological conditions, including various kinds of stress.

Diabetes insipidus: historical aspects

The contributions to our present knowledge and understanding of diabetes insipidus are briefly surveyed. Though a disease presenting with polyuria and thirst had been recognized since Antiquity, it was not until the 17. Century the distinction was made between diabetes insipidus and diabetes mellitus. At the beginning of the 20. Century almost nothing was known about the function of the pituitary. It was generally believed that diabetes insipidus was a renal disease. Two clinical observations in 1912 suggested an association between the hypophysis and diabetes insipidus. This view was supported by the recognition in 1913 that extract of the posterior lobe of the pituitary was effective in diabetes insipidus. Despite much evidence to the contrary, it was assumed that the antidiuretic hormone was produced in the intermediate lobe of the pituitary. Around 1950 it was finally established that 'the posterior lobe hormones' are in fact secreted in the hypothalamus. At the same time the antidiuretic hormone was isolated and synthesized. More recently, progress within genetics has made it possible to characterize in details other rare types of diabetes insipidus.

[PHARMACOLOGICALLY ACTIVE POLYPEPTIDES AND THE DIAMETER OF THE PIAL ARTERIES. EXPERIMENTAL STUDY WITH VASOPRESSIN, OXYTOCIN, BRADYKININ AND NEUROKININ]

A ação de quatro polipeptídeos farmacológicamente ativos (vasopressina, ocitocina, bradicinina e neurocinina) sôbre as artérias piais foi estudada em cães anestesiados com pentobarbital sódico e preparados para o registro da pressão arterial. Utilizou-se a técnica de Forbes 25, modificada por Me-laragno37 que permite a visibilização, a fotografia e a mensuração dos referidos vasos. Foram feitas 24 experiências, divididas em 5 grupos de animais: um grupo foi utilizado como contrôle e os outros quatro para o estudo de cada uma das drogas acima referidas, administradas por via venosa. Os resultados obtidos conduziram às seguintes conclusões: 1) a vasopressina não determina variação significativa no diâmetro das artérias da pia-máter, embora tenha provocado irregulares variações da pressão arterial; 2) a ocitocina causa intensa vasoconstrição pial, de curta duração, sem contudo modificar essencialmente a pressão arterial sistêmica; 3) a bradicinina aumenta o diâmetro das artérias da pia-máter, em paralelismo com um efeito hipotensor sistêmico; 4) a neurocinina promove dilatação das artérias da pia-máter, independentemente de eventual variação da pressão arterial sistêmica.