Guillermo Federico Wassermann
Universidade Federal do Rio Grande do Sul
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Fish Physiology and Biochemistry | 2004
Adriana Borges; Luciana V. Scotti; Daniele Rodrigues Siqueira; Daiane Follmann Jurinitz; Guillermo Federico Wassermann
The determination of hematologic parameters for jundiá Rhamdia quelencultivated in ponds is an easy and useful tool for the control of their sanitary and nutritional conditions. In the present work hematologic indices (RBC, WBC, Ht, Hb, MCV, MCH, MCHC), electrolytes (Cl, Na, K, Ca, Mg, P), metabolic products (creatinine, urea, ammonia, glucose, total protein, triglycerides, cholesterol, bilirubin) and enzymes (alanine and aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase) were measured in a population of jundiá. The mean ± SEM and range were established.
Life Sciences | 2011
Eloisa da Silveira Loss; Ana Paula Jacobus; Guillermo Federico Wassermann
This minireview describes the rapid signaling actions of follicle stimulating hormone (FSH) and testosterone in immature Sertoli cells mainly related to Ca(2+) inflow and the electrophysiological changes produced by hormones. The rapid membrane actions of FSH occur in a time frame of seconds to minutes, which include membrane depolarization and the stimulation of (45)Ca(2+) uptake. These effects can be prevented by pertussis toxin (PTX), suggesting that they are likely mediated by Gi-protein coupled receptor activation. Furthermore, these effects were inhibited by verapamil, a blocker of the L-type voltage-dependent Ca(2+) channel (VDCC). Finally, FSH stimulation of (45)Ca(2+) uptake was inhibited by the (phosphoinositide 3-kinase) PI3K inhibitor wortmannin. These results suggest that the rapid action of FSH on L-type Ca(2+) channel activity in Sertoli cells from pre-pubertal rats is mediated by the Gi/Gβγ/PI3Kγ pathway, independent of its effects on insulin-like growth factor type I (IGF-I). Testosterone depolarizes the membrane potential and increases the resistance and the (45)Ca(2+) uptake in Sertoli cells of the seminiferous tubules of immature rats. These actions were nullified by diazoxide (K(+)(ATP) channel opener). Testosterone actions were blocked by both PTX and the phospholipase C (PLC) inhibitor U73122, suggesting the involvement of PLC - phosphatidylinositol 4-5 bisphosphate (PIP2) hydrolysis via the Gq protein in the testosterone-mediated pathway. These results indicate that testosterone acts on the Sertoli cell membrane through the K(+)(ATP) channels and PLC-PIP2 hydrolysis, which closes the channel, depolarizes the membrane and stimulates (45)Ca(2+) uptake. These results demonstrate the existence of rapid non-classical pathways in immature Sertoli cells regulated by FSH and testosterone.
General and Comparative Endocrinology | 1991
Vera Lúcia Andrade Machado; Guillermo Federico Wassermann; Maria Marques
The presence of specific insulin binding sites in the thyroid gland of the turtle Chrysemys dorbigni has been previously reported. The purpose of the present work was to investigate the probable action of insulin on the uptake of [14C]deoxy-D-glucose ([14C]DG) and [14C]alpha-aminoisobutyric acid ([14C]AIB) in turtle (C. dorbigni) thyroid glands in vitro. Thyroid fragments (+/- 40 mg) were incubated at 25 degrees in Krebs-Ringer-bicarbonate buffer containing 0.2 microCi of [14C]DG or [14C]AIB without or with bovine insulin at different periods of time. The uptake of [14C]DG and [14C]AIB increased with incubation time. The presence of insulin (7 x 10(-6) M) in the incubation medium during 240 min did not modify the [14C]DG uptake. However if the thyroid fragments were previously incubated with insulin (60 min) and then incubated (240 min) with the same concentration of the hormone, the [14C]DG uptake was markedly increased. This stimulatory effect of insulin was dose-dependent. In similar experimental conditions, insulin also produced a significant increase in the uptake of [14C]AIB. Therefore, these findings strongly support the hypothesis that insulin might exert a direct action on the thyroid function.
Comparative Biochemistry and Physiology Part A: Physiology | 1984
Ana M.R Silva; Galba S Moraes; Guillermo Federico Wassermann
Abstract 1. 1. In this paper we studied the relationship between the seasonal variation of testicular morphology in the turtle Chrysemys dorbigni , the plasma levels of testosterone, the amino acid uptake by the testes and the environmental temperature (monthly mean temperature). 2. 2. The testicular weight, the plasma levels of testosterone and the spermatogenesis were at maximum from January to March (end of summer, beginning of autumn). 3. 3. The highest amino acid uptake coincides with the predominance of Sertoli and interstitial cells in the testes, that is, during the period of rising temperature (spring or mating period, October to December). At this time however the levels of testosterone are very low. 4. 4. The spermatozoa used in the mating period (spring) seem to be the ones stored in the “tubuli” epididymis which were matured in the previous cycle, since in the spring the seminiferous tubuli are lacking mature germinative cells. 5. 5. We conclude that the rise of temperature in the spring increases the metabolic activity of the testes (high amino acid uptake) and this metabolic reactivation leads to an increase in cell proliferation, testosterone levels, enzyme activity, and a new spermatogenic wave.
Frontiers in Physiology | 2010
Ana Paula Jacobus; Eloisa da Silveira Loss; Guillermo Federico Wassermann
The aim of this study was to evaluate the effect of pertussis toxin (PTX) on the depolarizing component of the action of follicle stimulating hormone (FSH) on the membrane potential (MP) of Sertoli cells, which is linked to the rapid entry of Ca2+ into cells and to the Ca2+-dependent transport of neutral amino acids by the A system. This model allowed us to analyze the involvement of Gi proteins in the action of FSH in these phenomena. In parallel, using an inactive analog of insulin-like growth factor type I (IGF-1), JB1, and an anti-IGF-I antibody we investigated the possible mediating role of IGF-I on these effects of FSH because IGF-I is produced and released by testicular cells in response to stimulation by FSH and shows depolarization effects on MP similar to those from FSH. Our results have the following implications: (a) the rapid membrane actions of FSH, which occur in a time-frame of seconds to minutes and include the depolarization of the MP, and stimulation of 45Ca2+ uptake and [14C]-methyl aminoisobutyric acid ([14C]-MeAIB) transport, are nullified by the action of PTX and, therefore, are probably mediated by GiPCR activation; (b) the effects of FSH were also nullified by verapamil, an L-type voltage-dependent Ca2+ channel blocker; (c) wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K), prevented FSH stimulation of 45Ca2+ entry and [14C]-MeAIB transport; and (d) these FSH actions are independent of the IGF-I effects. In conclusion, these results strongly suggest that the rapid action of FSH on L-type Ca2+ channel activity in Sertoli cells from 10- to 12-day-old rats is mediated by the Gi/βγ/PI3Kγ pathway, independent of the effects of IGF-I.
Comparative Biochemistry and Physiology Part A: Physiology | 1991
M.G. Fauth; K.P. Barreto; Guillermo Federico Wassermann
1. Insulin stimulated the [1-14C] methylaminoisobutyric acid and [1-14C] aminoisobutyric acid uptake in the bovine adrenal cortex or in the glomerulosa zone through the A system. 2. Verapamil nullified the insulin stimulatory action indicating that this hormonal action is probably related to the voltage-dependent Ca2+ channels.
Comparative Biochemistry and Physiology Part A: Physiology | 1982
Ana M.R Silva; Guillermo Federico Wassermann
Abstract 1. 1. The uptake of α-aminoisobutyric acid (AIB) by the testes of C. dorbigni has been investigated. 2. 2. This uptake reached a maximum during late spring and early summer and a minimum in autumn and winter. 3. 3. Testes from normal winter turtles acclimatised at 10. 25 or 31°C show increased AIB uptake with increased acclimatisation temperature. 4. 4. The acclimatisation of turtles increases the testicular uptake of AIB with respect to non-acclimatised controls. 5. 5. Hypophysectomized turtles have lower levels of AIB uptake but still show variation with season and acclimatisation. 6. 6. The seasonal variation in the ammo acid uptake appears to be due to testicular and hormonal cycles as well as to changes in membranes induced by acclimatisation.
Aquaculture Research | 2001
Leonardo Jose Gil Barcellos; V. M. Woehl; Guillermo Federico Wassermann; Rosmari Mezzalira Quevedo; I Ittzés; Marta Helena Krieger
Chemosphere | 2007
Adriana Borges; Luciana V. Scotti; Daniele Rodrigues Siqueira; Rebeca Zanini; Fernanda do Amaral; Daiane Follmann Jurinitz; Guillermo Federico Wassermann
General and Comparative Endocrinology | 2001
Leonardo Jose Gil Barcellos; Guillermo Federico Wassermann; Alexander P. Scott; Viviane M Woehl; Rosmari Mezzalira Quevedo; István Ittzés; Marta Helena Krieger; Francisco Lulhier
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Universidade Federal de Ciências da Saúde de Porto Alegre
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