M.D. Andrés
University of Santiago de Compostela
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Featured researches published by M.D. Andrés.
Fish Physiology and Biochemistry | 1996
José L. Soengas; E.F. Strong; J. Fuentes; J. A. R. Veira; M.D. Andrés
The capacity of carbohydrate and ketone bodies metabolism in brain and liver was evaluated in fed and food-deprived Atlantic salmon (Salmo salar) in a time period covering from 1 to 7 days (Experiment I), and in Atlantic salmon food deprived for 6 weeks, and food deprived for 4 weeks and refed for 2 weeks (Experiment II). The results obtained demonstrate for the first time in a teleost the existence of changes in brain metabolism due to food deprivation. Thus, decreased glucose levels in plasma are reflected in the brain by an increased mobilization of glycogen reserves, and by a decreased glycolytic capacity. Also, ketone bodies appear to increase their importance as a metabolic fuel from day 7 of food deprivation onwards. A possible increase in the gluconeogenic potential in brain simultaneously is not discarded. All these metabolic changes are reversed under refeeding conditions.
Aquaculture | 1992
José L. Soengas; P. Rey; G. Rozas; M.D. Andrés; M. Aldegunde
Abstract Glycogen, glucose, protein and glycogen phosphorylase and glycogen synthetase activity in liver, white muscle and kidney were determined in domesticated rainbow trout (Oncorhynchus mykiss) treated with 3,5,3′-triiodo-L-thyronine (T3), thyroxine (T4) and cortisol and combinations of all these hormones for 10 days. Plasma protein and glucose levels were also determined. Declines in liver glycogen and glucose were observed after cortisol treatment as compared to values obtained in controls (controls: 27.54 ± 1.73 mg glycogen/g and 16.81 ± 1.50 mg glucose/g) such as 15.94 ± 2.64 mg glycogen/g and 8.63 ± 1.22 mg glucose/g. T4 treatment did not produce any effects on the measured parameters. T3 plus T4 treatment caused a fall in hepatic glycogen and glucose levels ( 11.97 ± 1.27 mg glycogen/g and 8.98 ± 2.06 mg/g, respectively). All cortisol and thyroid hormone combinations produced a fall in liver glycogen levels (range between 6.07 ± 1.19 and 16.38 ± 1.56 mg glycogen/g) as well as an increase (from 37 to 44%) in glycogen phosphorylase activity. No changes were observed in any of the measured parameters for the different hormone treatments assessed in white muscle and kidney. Under our experimental conditions, cortisol and probably T3 are involved in liver glycogen mobilization and apparently do not elicit a response in white muscle and kidney.
Comparative Biochemistry and Physiology B | 1993
José L. Soengas; P. Barciela; J. Fuentes; J. Otero; M.D. Andrés; M. Aldegunde
Abstract 1. 1. A study of the levels of glycogen and glucose, as well as the activities of glycogen phosphorylase (GPase), glycogen synthetase (GSase), fructose 1,6-bisphosphatase (FBPase), phosphofructokinase (PFK), glucose 6-phosphate dehydrogenase (G6PDH), pyruvate kinase (PK) and lactate dehydrogenase (LDH) was carried out in livers of domesticated rainbow trout ( Oncorhynchus mykiss ) of two different weights [small (80 g) and large (140 g)] after transfer to seawater (28 p.p.t.) for 21 days. 2. 2. The results indicate that metabolic changes during adaptation of rainbow trout to seawater appear to occur in two stages which, in addition, appear to be size-dependent. 3. 3. During the first stage a clear glycogenolysis (associated with an increase in GPase activity and a decrease in GSase activity) and hyperglycemia were observed both in small and large animals, being higher in the small ones. 4. 4. A seeming increase in gluconeogenesis (as indicated by the activation of FBPase activity) was observed only in large animals. 5. 5. The mobilization of energy reserves could be associated with the increase in energetic demand of the osmoregulatory organs. On the other hand, the second stage indicates that a successful adaptation to seawater did not occur, since the animals ceased to feed from day 7 of the experiment onwards.
Fish Physiology and Biochemistry | 1998
José L. Soengas; E.F. Strong; M.D. Andrés; M. Aldegunde
The levels of glycogen, lactate, acetoacetate and β-hydroxybutyrate in brain as well as glycogen and lactate levels in liver, and glucose levels in plasma were evaluated in rainbow trout, Oncorhynchus mykiss, injected with ethanol/saline (5/95; v/v) alone (controls) or containing melatonin at three different doses 0.25, 0.5 and 1 mg kg-1. The results obtained demonstrate, for the first time in a teleost fish, the existence of changes in brain carbohydrate and ketone body metabolism due to melatonin treatment. Thus, a clear dose-dependent decrease was observed in brain and liver glycogen levels, whereas a clear dose-response increase was observed in brain for lactate, acetoacetate and β-hydroxybutyrate levels, and in plasma for glucose levels. CO2 production from glucose was also tested in brains of pooled fish and these rates were not altered by melatonin treatment. Altogether, these results suggest that melatonin may play an indirect role, possibly through alterations in insulin physiology, in the regulation of carbohydrate and ketone body metabolism in brain of rainbow trout.
Comparative Biochemistry and Physiology B | 1991
José L. Soengas; J. Otero; J. Fuentes; M.D. Andrés; M. Aldegunde
Abstract 1. 1. Assessment of glycogen and glucose content and glycogen phosphorylase, glycogen synthetase, hexokinase and fructose 1,6-bisphosphatase activity in liver and white muscle of domesticated rainbow trout (Oncorhynchus mykiss) transferred to diluted seawater (12 p.p.t.). Plasma glucose levels were also determined. 2. 2. A decline in liver glycogen content was observed throughout the 12–120 hr period in diluted seawater (dSW). Liver free glucose also showed a decrease, though only significant at 120 hr in dSW. 3. 3. The activity of liver glycogen phosphorylase a and a + b was higher in dSW animals, but glycogen synthetase was unchanged. 4. 4. No changes in liver hexokinase and fructose 1,6-biphosphatase activity were observed. 5. 5. In white muscle and plasma only white muscle glycogen synthetase activity showed a change, in particular a decline in dSW animals. 6. 6. Although domesticated rainbow trout do not naturally migrate to seawater, these data suggest that a depletion of liver reserves occurred in a way similar to that described for other salmonids.
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology | 2000
M. Aldegunde; M.D. Andrés; José L. Soengas
Abstract The influx of glucose into the brain and plasma glucose disappearance were estimated in rainbow trout (Oncorhynchus mykiss) intravenously injected (1 ml · kg−1 body weight) with a single dose (15 μCi · kg−1 body weight) of 3-O-methyl-D-[U-14C]glucose ([U-14C]-3-OMG) at different times (2–160 min), and after intravenous injection at 15 min of increased doses (10–60 μCi · kg−1 body weight) of [U-14C]-3-OMG. Brain and plasma radiotracer concentrations were measured, and several kinetic parameters were calculated. The apparent brain glucose influx showed a maximum after 15–20 min of injection then decreased to a plateau after 80 min. Brain distribution space of 3-OMG increased from 2 min to 20 min reaching equilibrium from that time onwards at a value of 0.14 ml · g−1. The unidirectional clearance of glucose from blood to brain (k1) and the fractional clearance of glucose from brain to blood (k2) were estimated to be 0.093 ml · min−1 · g−1, and 0.867 min−1, respectively. A linear increase was observed in brain and plasma radiotracer concentrations when increased doses of [U-14C]-3-OMG were used. All these findings support a facilitative transport of glucose through the blood-brain barrier of rainbow trout with characteristics similar to those observed in mammals. The injection of different doses of melatonin (0.25–1.0 mg · kg−1) significantly increased brain glucose influx suggesting a possible role for melatonin in the regulation of glucose transport into the brain.
Biological Rhythm Research | 1990
P. Rey; G. Rozas; M.D. Andrés; M. Aldegunde; E. Rebolledo
Abstract Seasonal changes on gill ATPases activities of domesticated rainbow trout (Salmo gairdneri ), reared under natural conditions, were studied during 1988. There is a peak in the (Na+‐K+) ATPase activity between May 10th and July 13rd. The highest average activity appears during June, just before and after summer solstice (June 15th and 29th). Ca2+‐, Mg2+‐ and HCO 3‐ATPases show annual significant variations in their activities (p<0.05); nevertheless, none of them present a seasonal pattern. It seems to be that, of all implicated enzymes on ionosmotic regulation, only (Na∗‐K∗)‐ATPase shows circannual variations that can be related to preadaptative changes of the smoltification process.
Fish Physiology and Biochemistry | 1990
G. Rozas; P. Rey; M.D. Andrés; E. Rebolledo; M. Aldegunde
The levels of tryptophan (Try), 5-hydroxytryptamine (serotonin, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were determined in the brain regions of rainbow trout (Oncorhynchus mykiss) by high performance liquid chromatography with electrochemical detection (HPLC-EC). Brain tryptophan concentrations varied from 3.972 ± 357 ng/g cerebellum) to 8.841 ± 772 ng/g (hypothalamus). The 5-HT concentrations varied from 69 ± 7 ng/g (optic tectum) to 573 ± 34 ng/g (hypothalamus). The concentrations of 5-HIAA varied from 29 ± 3 ng/g (medulla oblongata) to 68 ± 7 ng/g (hypothalamus). Total and free serum tryptophan levels were also determined; in adult rainbow trout 92% of the serum tryptophan was observed to be free i.e., not protein-bound.
Comparative Biochemistry and Physiology B | 1993
José L. Soengas; P. Barciela; J. Fuentes; J. Otero; M.D. Andrés; M. Aldegunde
Abstract 1. 1. A study of glycogen and glucose levels, as well as the activities of glycogen phosphorylase (GPase), glycogen synthetase (GSase), fructose 1,6-bisphosphatase (FBPase), phosphofructokinase (PFD) and glucose 6-phosphate dehydrogenase (G6PDH) was carried out in white and red muscle of domesticated rainbow trout ( Oncorhynchus mykiss ) of two different weights [small(80g) and large (140g)] after transfer to seawater (28 p.p.t.) for 21 days. 2. 2. A fall in glycogen levels for both sizes assessed was observed in both types of muscle. 3. 3. Glucose levels followed opposite trends in both tissues in seawater animals: they were higher in red muscle, but smaller in white muscle when compared with those of freshwater animals. 4. 4. An increase in glycolytic activity was only observed in white muscle. 5. 5. These results seem to indicate that seawater adaptation of rainbow trout induces glycogenolysis in white and red muscle, with the glucose produced in white muscle being used in situ through glycolysis.
Aquaculture | 1992
José L. Soengas; J. Fuentes; J. Otero; M.D. Andrés; M. Aldegunde
Abstract To determine the metabolic changes related to gill (Na + -K + )-ATPase activity, a study of the levels of glycogen, glucose, and protein as well as of the activities of glycogen phosphorylase (GPase), glycogen systhetase (GSase), fructose 1,6-bisphosphatase (FBPasc) and hexokinase (HK), was carried out in liver, white muscle and kidney of rainbow trout ( Oncorhynchus mykiss ) reared in freshwater. Plasma protein, glucose and liver lactate levels were also measured. In liver an increment in the levels of glycogen, glucose and lactate was observed prior to an increase in ATPase activity. A decline in these parameters, associated with a drop in glycemia, was detected when ATPase activity was increased. Variations in the activities of both GPase and GSase were found associated with changes in levels of glycogen. A peak in liver FBPase activity and a decrease in liver HK activity was found when ATPase activity was increased. In white muscle and kidney, only the increase in kidney FBPase activity seems to be related to the rise in ATPase activity. These data suggest that, in contrast to the results obtained in white muscle and kidney, a storage followed by a depletion of liver reserves occurs coincidentally with the increase and subsequent decline in gill (Na + -K + )-ATPase activity.