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M Haluzík

Publications and source records attributed to M Haluzík.

65 records · Page 4Linked to original sources
PubMed1997

Comparison of in vivo long-term treatment of rats by methylene blue with its in vitro effects on thyroid hormone--nuclear receptor complex formation in liver.

The present study was undertaken to investigate both in vitro effects of methylene blue and its long-term in vivo influence on 3,5,3'-L-triiodothyronine nuclear receptor binding characteristics in rat liver. In vitro, methylene blue at 1 nmol/l was found to inhibit (p < 0.05) the 3,5,3'-L-triiodothyronine (T3) specific binding to its cognate nuclear receptors. Methylene blue at 100 nmol/l significantly (p < 0.05) reduced the thyroid hormone receptor (TR) concentration (expressed as the TR maximal binding capacity). The equilibrium association constant (Ka) of that reduced number of TR resulting from 100 nmol/l methylene blue TR treatment was significantly higher (p < 0.05), when compared to samples without methylene blue. Moreover, the T3 was found to dissociate from the TR-T3 complex in the presence of 1 mumol/l methylene blue. In vivo long-term treatment of rats with 0.125%, 0.25% or 0.5% methylene blue for 28 days did not affect either the TR maximal binding capacity (Bmax) or the Ka values in comparison with rats fed a standard laboratory diet. The data based on both in vitro or in vivo experiments suggest that in spite of a direct and quick in vitro effect of methylene blue on liver TR concentration and/or TR-T3 dissociation, a long-term in vivo treatment of rats by three different methylene blue concentrations does not affect the thyroid hormone receptor status (the concentration and the affinity) in the liver.

Animals↗
PubMed1997

[Changes in thyroid function in rats after administration of methylene blue and interactions with estrogens and acetylsalicylic acid].

We have studied the thyroxine and triiodothyronine concentrations in male rats--the control, groups treated separately with estradiol benzoate, acetylsalicylic acid and methylene blue and with combinations of these substances. We have found out that the treatment with acetylsalicylic acid significantly lowers the thyroxine and triiodothyronine serum concentrations. The estradiol benzoate as well as methylene blue inhibited the drop in the serum thyroxine level when administered simultaneously with acetylsalicylic acid. The serum triiodothyronine decrease after acetylsalicylic acid treatment was inhibited by methylene blue and estradiol benzoate only in one of our two experiments. The simultaneous treatment with estradiol benzoate, acetylsalicylic acid and methylene blue did not change the triiodothyronine concentration comparing to control group and decreased the thyroxine serum concentration.

Animals↗
PubMed1997

[NO-synthase inhibitors and endocrine gland function].

Nitric oxide is a reactive gas with multiple important physiological and pathophysiological effects in the human body. Beside the accepted fact that NO is identical with endothelium derived relaxing factor, which mediates the acetylcholine induced relaxation of blood vessel wall, important roles of NO in the functional modulation of endocrine glands, and in the outbreak and progress of experimental diabetes in rats have been proved. The article summarises the current knowledge about the action of NO in some endocrine glands with respect to the possibility of treatment by means of NO-synthase inhibitors administration.

Animals↗
PubMed1997

[The effect of an NO-synthase inhibitor, methylene blue, on the function of certain endocrine glands].

Methylene blue is a thiazine dye, which has been used in the clinical medicine as disinfection agent and in treatment of methemoglobinemia. The recent investigations showed that this dye is able to inhibit the activation of guanylate cyclase pathway in the guanylate cyclase or in the NO-synthase level. This paper summarizes the experimentally obtained results concerning the influence of methylene blue on the hypothalamic, hypophyseal, thyroid and testicular function in rats. The possible mechanism of its influence with potential role of nitric oxide in the modulation of regulating pathways in these endocrine glands is discussed.

Animals↗
PubMed1997

The decrease of serum leptin levels in oestrogen-treated male mice.

Adipocyte hormone leptin (OB protein) is considered to be an "adiposity signal" regulating body weight homeostasis and energy balance. We have previously reported that oestrogens (oestradiol-benzoate) significantly decrease the body weight in male rats, increase anterior pituitary and serum levels of the intracellular messenger cAMP, which activates cAMP-dependent protein kinase A, their targets include hormone-sensitive lipase and they influence the brain sympathetic system. The present study tested our hypothesis that oestrogens could influence serum leptin levels in male mice. We found that chronic administration of oestradiol-benzoate significantly attenuated serum levels of leptin, in the dependence on the duration of its administration, and simultaneously decreased body weight. We suppose that oestrogens affect leptin levels interacting with the signal transmission system of cAMP, possibly at the genome level. Our observations that the food consumption of mice with simultaneously decreased body weight and levels of serum leptin support the idea that there exists a satiety factor that counters the effect of low leptin.

Adipocytes↗
PubMed1995

An increase in the blood thyroxine level after methylene blue in rats: the interaction with carbimazole.

Anterior pituitary (AP) weight, thyroid weight, the serum thyroxine (T4) level, the thyroid T4 and cAMP content, the serum TSH level and the TSH and cAMP content of the AP and thyroid were measured in control rats, rats given methylene blue (MB) in their food, rats given the thyroid-blocking agent carbimazole (CARB) and rats fed both MB and CARB. AP weight fell slightly after MB in both intact and CARB--fed animals. Thyroid weight rose strongly after CARB, MB partly inhibited this increase. The cAMP content of the thyroid rose after CARB; this increase was likewise blocked by MB, MB alone had no effect on the thyroid cAMP concentration. Previous observations showing that MB produced an increase in the blood T, were confirmed. The T4 level fell, of course, after CARB and the decrease was partly inhibited by MB. The T4 content of the thyroid also fell after CARB, this decrease was completely reversed by MB. The blood TSH level fell slightly after MB and rose 7--fold after a CARB blockade of the thyroid; this increase was completely inhibited by MB. The TSH content of the AP fell after MB in both intact and CARB--fed animals. The cAMP content of the AP fell after MB, it was unaffected by CARB. Thus, in some way, MB raised the blood thyroxine level in both intact and CARB--fed animals and strongly depressed the TSH content in the serum and the AP given alone or with CARB. The mechanism of this action should be a result of MB interaction in thyroid hormone metabolism and their binding activity on specific regulatory elements. It is a problem for future experiments.

Administration, Oral↗
PubMed1995

Methylene blue--an endocrine modulator.

Methylene blue (MB) is a thiazine dye used in the treatment of methemoglobinemia. It may represent a new class of anti-oxidant drugs which competitively inhibit the reduction of molecular oxygen to superoxide by acting as an alternative electron acceptor for tissue oxidases. Because of its strong free radicals scavenging effect MB was experimentally used in the treatment of reperfusion syndrome. MB is soluble guanylate cyclase inhibitor. It was found to inhibit the stimulation of soluble guanylate cyclase by nitric oxide and vasodilatators. Another effect of MB is inhibition of prostacyclin synthesis by endothelial cells and isolated arteries independently of its effects on cGMP accumulation. We investigated the MB in series of experimental endocrine situations in which its free radicals scavenging effect could play a role. We observed that MB partly inhibited the increase in adenohypophyseal weight, cAMP and blood prolactin levels in male rats after the administration of estrogens. MB also blocked the increase of another free radicals scavenger-the metalloenzyme ceruloplasmin in the blood of estrogenized rats and prevented the increase of bone mineral after estradiol treatment. MB produced a decrease in adenohypophyseal ascorbic acid content. The blood thyroxine levels increased and the anterior pituitary TSH concentration decreased after MB treatment.

Animals↗
PubMed1995

Adenohypophyseal ascorbic acid: influences of oestradiol and methylene blue.

The ascorbic acid (AA) concentration in anterior pituitary and blood plasma was measured by the Roe-Kuether method in control rats and rats treated with oestradiol benzoate alone, methylene blue alone and with both oestradiol and methylene blue. We have found that methylene blue alone caused a significant drop in hypophyseal both AA and plasma AA concentrations. Methylene blue treatment prevented the increase in plasma AA concentration in oestradiol benzoate-treated rats.

Animals↗
PubMedDate not supplied

Relationship of serum leptin levels and selected nutritional parameters in patients with protein-caloric malnutrition.

Leptin is a protein hormone produced by adipocytes that reflects the body fat content, i.e., its serum concentration in healthy individuals positively correlates with the body mass index and body fat content. Serum leptin levels are lower in both patients with anorexia nervosa and protein-caloric malnutrition caused by chronic non-malignant illnesses. The aim of the present study was to compare serum leptin levels and selected, routinely used nutritional parameters in women with anorexia nervosa (n = 17), severely malnourished patients with short bowel syndrome (n = 13), and control non-obese healthy women (n = 17) to clarify the relation between selected nutritional parameters and serum leptin levels. We found that serum leptin levels in the anorexia nervosa and short bowel syndrome groups were significantly lower than those in the control group (in ng/mL: 3.63 +/- 1.64 and 2.59 +/- 1.17 versus 12.06 +/- 7.59, respectively). Protein malnutrition expressed by decrease in serum concentrations of total protein, albumin, and prealbumin was more pronounced in the short bowel syndrome group. Triceps skin fold, arm muscle circumference, and body mass index were significantly lower in the patient group than in the control group and did not significantly differ between the short bowel syndrome and anorexia nervosa groups. No significant difference in serum leptin concentration between the short bowel syndrome and anorexia nervosa groups was found. Serum leptin levels correlated positively with body mass index and triceps skin fold in the control and anorexia nervosa groups but not in the short bowel syndrome group. We conclude that serum leptin levels in patients with anorexia nervosa and short bowel syndrome are significantly lower than in healthy individuals and have no statistically significant relation to serum total protein, abumin, and prealbumin.

Adult↗
PubMedDate not supplied

The influence of short-term fasting on serum leptin levels, and selected hormonal and metabolic parameters in morbidly obese and lean females.

The aim of our study was to compare the changes of serum leptin levels after 24-h fasting in morbidly obese and lean females and to search for hormonal and metabolic factors responsible for the changes in serum leptin levels. Fourteen morbidly obese and twelve lean females were included in the study. The blood for leptin, insulin, cortisol, blood glucose (BG), beta-OH-butyrate (beta-OH), dehydroepiandrosterone (DHEA) and DHEA-sulphate (DHEA-S) measurements was withdrawn before and after a 24-h fast. Basal body mass index (BMI), serum leptin, insulin and beta-OH levels were significantly higher in the obese compared to the lean group. The 24-h fasting decreased significantly BMI, serum leptin (by 20% in obese vs. 62% in lean subjects), insulin (by 23.3% in obese vs. 23.1% in lean subjects) and increased beta-OH (by 36% in obese vs. 1300% in lean subjects). Basal serum leptin levels correlated positively with BMI in both groups and with insulin levels in the obese group. The multiple regression analysis using delta leptin as dependent and the basal values of the rest of studied parameters as independent variables revealed that in lean subjects serum cortisol together with DHEA-S and BMI accounted for 71% of variations of the change of serum leptin levels (delta leptin = 0.31- 0.0101 cortisol + 0.0012 DHEA-S + 0.37 BMI). In obese subjects the 43.9% of variations of the change of serum leptin levels was explained by BMI together with age and DHEA-S levels (delta leptin = 36.09 + 0.35 BMI - 0.717 age- 0.008 DHEA-S). The drop of serum leptin levels after 24-h starvation is significantly blunted in obese compared to lean subjects. The reason for the difference is probably the insulin resistance possibly further modified by different DHEA-S levels.

3-Hydroxybutyric Acid↗