Biomedical subjects

J Nedvídková

Publications and source records attributed to J Nedvídková.

At least 19 recordsLinked to original sources

PubMed2006

Increased insulin sensitivity in patients with anorexia nervosa: the role of adipocytokines.

Anorexia nervosa (AN) is characterized by self-induced starvation leading to severe weight and fat loss. In the present study, we measured fasting plasma levels of adiponectin, leptin, resistin, insulin and glucose in 10 women with a restrictive type of AN and in 12 healthy women (C). Insulin sensitivity was determined according to homeostasis model assessment of insulin resistance (HOMA-R). Plasma resistin, leptin and insulin levels were significantly decreased, whereas plasma adiponectin levels were significantly increased in patients with AN compared to the C. HOMA-R was significantly decreased in patients with AN compared to the C group. Plasma adiponectin and leptin concentrations negatively and positively correlated with the body mass index and percentage body fat in both groups. Plasma adiponectin levels were negatively related to plasma insulin levels in the AN group only. In conclusion, we demonstrated that AN is associated with significantly decreased plasma leptin and resistin levels, markedly increased plasma adiponectin levels and increased insulin sensitivity. Plasma leptin and adiponectin levels were related to the body size and adiposity. Hyperadiponectinemia could play a role in increased insulin sensitivity of patients with AN. Neither body size and adiposity nor insulin sensitivity are the major determinants of plasma resistin levels in AN.

Adipokines↗

PubMed2006

Dynamic changes of orexin A and leptin in obese children during body weight reduction.

In this study, we describe changes of plasma levels of the hypothalamic neuropeptide orexin A in obese children during the reduction of body weight and its relationship to other biochemical and anthropometrical parameters. We measured orexin A fasting plasma levels by the RIA method in 58 obese children--33 girls and 25 boys; mean age 13.1+/-0.38 years (range 7-18.5) before and after 5 weeks of weight-reduction therapy. Leptin, IGF-1, and IGFBP-3 levels were measured in all the subjects and were compared to orexin A levels and anthropometrical data. Average weight in subjects before weight-reduction was 74.2+/-2.79 kg and after weight-loss 67.4+/-2.60 kg (p<0.0001). Orexin A levels before the therapy were 33.3+/-1.97 pg/ml and after the therapy 51.7+/-3.07 pg/ml (p<0.0001). Levels of orexin A were not significantly different between girls and boys (p=0.7842). We found negative correlation between orexin A and age (r = -0.5395; p<0.0001), body height (r = -0.4751; p=0.0002), body weight (r = -0.4030; p=0.0017) and BMI (r = -0.2607; p=0.0481). No correlation was found between orexin A and IGF-1, IGFBP-3 or leptin. Orexin A plasma levels increased during body weight loss, whereas the reverse was true for leptin levels. These findings support the hypothesis that orexin A may be involved in regulation of nutritional status in children.

Adolescent↗

PubMed2006

[The role of adiponectin in increased insulin sensitivity of patients with anorexia nervosa].

The aim of the present study was to determine the relationship between plasma levels of adipocytokine adiponectin and the degree of insulin sensitivity in patients with anorexia nervosa (AN). AN is a psychiatric disorder characterized mainly by severe malnutrition and loss of body fat. We measured fasting plasma adiponectin, insulin and glucose levels in ten women with a restrictive type of AN and in twelve healthy normal-weight women. Plasma adiponectin levels were significantly increased in patients with AN compared to healthy women (p < 0.01) and were negatively related to body mass index and percent body fat in both groups. Plasma adiponectin levels were negatively related to plasma insulin levels in the AN group only. Using homeostasis model assessment of insulin resistance (HOMA-IR), we found significantly increased insulin sensitivity in patients with AN compared to control women (p < 0.05). In conclusion, hyperadiponectinemia in patients with AN might contribute to increased insulin sensitivity in these patients.

Adiponectin↗

PubMed2005

Increased lipolysis of subcutaneous abdominal adipose tissue and altered noradrenergic activity in patients with Cushing's syndrome: an in-vivo microdialysis study.

Cushing's syndrome is associated with typical central redistribution of adipose tissue. The aim of the study was to assess lipolysis and catecholamines and their metabolites in subcutaneous abdominal adipose tissue using an in-vivo microdialysis technique. Nine patients with Cushing's syndrome and nine age-, gender- and body mass index (BMI)-matched control subjects were included in the study. Local glycerol concentrations were significantly increased in subcutaneous adipose tissue of patients with Cushing's syndrome (p<0.001). Plasma noradrenaline, dihydroxyphenylglycol and dihydroxyphenylalanine were decreased in patients with Cushing's syndrome (p<0.02, p<0.05, and p<0.02, respectively). Adrenaline, noradrenaline, dihydroxyphenylglycol and dihydroxyphenylalanine concentrations in subcutaneous abdominal adipose were non-significantly higher in patients with Cushing's syndrome. In conclusion, we showed that lipolysis in subcutaneous adipose tissue of patients with Cushing's syndrome is significantly increased as compared to healthy subjects. This finding together with non-significantly increased local catecholamine concentrations in these patients suggests a possible link between increased lipolysis and catecholaminergic activity in subcutaneous adipose tissue.

Abdomen↗

PubMed2005

Adiponectin, an adipocyte-derived protein.

Adipose tissue is a hormonally active tissue, producing adipocytokines which may influence activity of other tissues. Adiponectin, abundantly present in the plasma increases insulin sensitivity by stimulating fatty acid oxidation, decreases plasma triglycerides and improves glucose metabolism. Adiponectin levels are inversely related to the degree of adiposity. Anorexia nervosa and type 1 diabetes are associated with increased plasma adiponectin levels and higher insulin sensitivity. Decreased plasma adiponectin levels were reported in insulin-resistant states, such as obesity and type 2 diabetes and in patients with coronary artery disease. Activity of adiponectin is associated with leptin, resistin and with steroid and thyroid hormones, glucocorticoids, NO and others. Adiponectin suppresses expression of extracellular matrix adhesive proteins in endothelial cells and atherosclerosis potentiating cytokines. Anti-atherogenic and anti-inflammatory properties of adiponectin and the ability to stimulate insulin sensitivity have made adiponectin an important object for physiological and pathophysiological studies with the aim of potential therapeutic applications.

Adipocytes↗

PubMed2004

Increased subcutaneous abdominal tissue norepinephrine levels in patients with anorexia nervosa: an in vivo microdialysis study.

The present study was designed to measure interstitial levels of norepinephrine-regulating lipolysis (NE) in subcutaneous abdominal adipose tissue of anorexia nervosa (AN) patients and control subjects under basal conditions and after the local administration of an inhibitor of NE re-uptake, maprotiline. In vivo microdialysis technique was used to assess subcutaneous adipose NE levels in five women with AN (body mass index 14.62+/-0.47 kg/m(2)) and six age-matched controls (22.1+/-0.52 kg/m(2)). NE was assayed using high performance liquid chromatography with electrochemical detection after batch alumina extraction. Measured basal adipose tissue NE levels reflecting its interstitial levels were significantly increased in AN patients compared to the controls (106.0+/-20.9 vs. 40.0+/-5.0 pg/ml). The local maprotiline administration resulted in a significant increase in adipose tissue NE levels (AN patients: 440.0+/-28.6 vs. 202.0+/-33.0 pg/ml in the controls) in both groups. Markedly increased subcutaneous abdominal adipose tissue NE levels in AN patients compared to control subjects reflect increased sympathetic nervous system activity but not altered membrane noradrenergic transporter system in anorexia nervosa patients.

Abdomen↗

PubMed2003

Application of in vivo microdialysis to measure leptin concentrations in adipose tissue.

Microdialysis is a relatively new in vivo sampling technique, which allows repeated collecting of interstitial fluid and infusion of effector molecules into the tissue without influencing whole body function. The possibility of using microdialysis catheter with a large-pore size dialysis membrane (100 kDa) to measure concentrations of the adipocyte-derived peptide hormone leptin in interstitial fluid of adipose tissue was explored. Krebs-Henseleit buffer with 40 g/l dextran-70 was used to prevent perfusion fluid loss across the dialysis membrane. The relative recovery of leptin in vitro was determined using CMA/65 microdialysis catheter (100 kDa cut-off, membrane length 30 mm; CMA, Stockholm, Sweden) and four perfusion rates were tested (0.5, 1.0, 2.0, 5.0 microl/min). Furthermore, the microdialysis catheter CMA/65 was inserted into subcutaneous abdominal adipose tissue of 11 healthy human subjects and leptin concentrations in the interstitial fluid of adipose tissue in vivo were measured. The present findings are the first documentation on the use of microdialysis to study local leptin concentrations in the interstitial fluid of adipose tissue.

Adipocytes↗

PubMed2003

[Recently discovered hormones with a role in energy homeostasis].

Adipocytal hormones resistin and adiponectin and gastric peptide ghrelin are recently discovered hormones, which are considered to take part in energy metabolism regulation. Resistin is expressed in adipose tissue only and its increased levels could cause insulin resistance and thus link obesity with type 2 diabetes. Adiponectin, as well as resistin, are products of genes, expressed in adipose tissue. Adiponectin could prevent development of aterosclerosis and it could play a role in anti-inflammatory reactions. Ghrelin is produced mainly in the stomach. Beside its role in long-term regulation of energy metabolism, it is involved in the short-term regulation of feeding. Main roles of resistin, adiponectin and ghrelin are summarised in the presented overview.

Adiponectin↗

PubMed2003

[Use of the in vivo microdialysis technique in basic and clinical research].

Microdialysis is in vivo technique that permits monitoring of local concentrations of metabolites and drugs at specific sites in the body that makes it an attractive tool for the basic and clinical research. Microdialysis entered the experimental studies of the brain, and later also of the peripheral tissues such as adipose and muscle tissues, kidney, lung, eye, skin, and blood. There are several critical factors in the experimental implementations of microdialysis: the probe, the perfusion solution, tissue integrity, and the sensitivity of microdialysate analysis method. When the experimental conditions are optimised to give valid results, microdialysis can provide numerous data from the relatively small number of individual subjects. It can bring about detailed clinical information reflecting free metabolite and drug concentrations in studied tissues and/or in plasma. With the progress of analytical methods, applications and importance of the microdialysis technique in clinical and pharmacokinetic research and diagnostics will increase.

Humans↗

PubMed2001

The role of dopamine in methylene blue-mediated inhibition of estradiol benzoate-induced anterior pituitary hyperplasia in rats.

Recently, we demonstrated that methylene blue partially inhibited estradiol-benzoate-induced anterior pituitary hyperplasia in rats. Since central dopaminergic systems participate in the regulation of estrogen-induced anterior pituitary growth and tumor transformation, this study examined whether a 3-week treatment with methylene blue could affect anterior pituitary levels of dopamine (DA), dihydroxyphenylalanine (DOPA), and dihydroxyphenylacetic acid and dopamine (D-2) receptors in male rats. Compared to controls, methylene blue significantly decreased anterior pituitary weight, increased basal anterior pituitary DA levels, and inhibited estradiol benzoate-induced decreases in anterior pituitary DA concentrations. Furthermore, we found that methylene blue alone decreased anterior pituitary D-2 receptor number. Methylene blue given in combination with estradiol benzoate partially inhibited estradiol benzoate-induced anterior pituitary growth and estradiol benzoate-induced increases in D-2 receptor number. Estradiol benzoate-treated rats had significantly lower anterior pituitary DOPA accumulation after intraperitoneal administration of 3,4-hydroxybenzyl-hydrazine dihydrochloride (NSD-1015), an irreversible inhibitor of L-aromatic amino acid decarboxylase whereas methylene blue did not affect anterior pituitary DOPA accumulation when compared to controls. Methylene blue decreased anterior pituitary prolactin levels and inhibited increases in anterior pituitary prolactin after estradiol benzoate administration. The present results suggest that anterior pituitary DA may play an important role in estrogen-induced anterior pituitary hyperplasia and tumor formation and that antioxidant drugs such as methylene blue may attenuate estrogen-induced pituitary growth. This may occur via increases in anterior pituitary DA levels associated with down-regulation of anterior pituitary D-2 receptors.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

Pain modulation role of melatonin in eating disorders.

The objective of this study was to test the effect of melatonin on thermal pain threshold in female patients with eating disorders. Fourteen patients were included in the study. We found a parabolic relation between pain threshold and the content of urine sulfatoxymelatonin (r = 0.6299, P < 0.05). We can speculate that increase in severity of eating disorder pathology may decrease both the melatonin level and pain sensitivity. In contrast with expected melatonin analgesic effect, our results showed its possible normalizing influence as well on pathologically decreased pain sensitivity.

Adult↗

PubMed2001

Brain maldevelopment and neurobehavioural deviations in adult rats treated neonatally with indomethacin.

The risk of neurodevelopmental toxicity was studied in indomethacin (INDO), an inhibitor of prostaglandin synthesis, which is used in at-risk neonates to prevent the consequences of brain intraventricular haemorrhage or to accelerate the closure of patent ductus arteriosus. Model experiments were carried out in rats of the Wistar strain and Konárovice breed. The drug dose (2 mg/kg, s.c.) was applied to rat pups either once or twice in the following way: (1) on postnatal day 4 (PD:4) or postnatal days 4 and 5 (PD:4-5), i.e. model of brain ontogenic developmental stage in human fetus/preterm neonate of 7-month-gestational age; (2) on postnatal day 9 (PD:9) or postnatal days 9-10 (PD:9-10), i.e. model of brain ontogenic stage in full-term human newborn. The rats were followed up during development (body weight, maturation) until adulthood (age 3-9 months) using tests of behaviour (open field, social memory), nociception (tail flick, plantar test), reproduction and brain neurobiological analysis. The results were evaluated by comparison of litter-mates: treated vs control. No differences between INDO and controls were found in developmental landmarks, adult social memory or reproduction. The pattern of behavioural and neuroendocrine deviations in adult animals was dependent on the ontogenic stage exposed to drug insult. INDO rats of the groups PD:4 and PD:4-5 revealed depression of open field motor activity and emotional reactivity, and higher pituitary weight with lower TSH content. On the other hand, deviations in adult INDO groups PD:9 and PD:9-10 were characterized by pain hypersensitivity, lower pituitary weight with unchanged TSH content and deficit of monoamine transmission in the hypothalamus.

Animals↗

PubMed2001

[Relation between serum leptin levels and selected nutritional parameters in hemodialyzed patients].

Leptin is a protein hormone produced predominantly by adipocytes. Its serum concentrations positively correlate with body fat content and body mass index (BMI) i.e. they are lower in lean than obese subjects. The aim of our study was to compare serum levels of leptin, selected nutritional parameters and serum lipids in hemodialysed patients (n = 46) and healthy subjects (n = 24) and to explore the relationship between serum leptin levels and the rest of nutritional parameters in both groups. The tendency towards higher serum leptin levels in hemodialysed patients compared to control group was found, but the difference did not reach the statistical significance (24.31 +/- 24.06 ng/ml vs. 7.97 +/- 4.4 ng/ml). The leptin/body fat content ratio was significantly higher in hemodialysed patients compared to control subjects (0.85 +/- 0.74 vs. 0.27 +/- 0.11, p plain 0.01). The serum total protein, transpherine, albumin and cholesterol levels were significantly lower in hemodialysed patients compared to control group (68.14 +/- 5.56 g/l vs. 75.53 +/- 3.43 g/l; 2.04 +/- 0.49 g/l vs. 2.5 +/- 0.23 g/l; 33.65 +/- 2.86 g/l vs. 48.38 +/- 3.5 g/l; 4.56 +/- 1.19 mmol/l vs. 5.82 +/- 0.98 mmol/l; p = 0.001). Serum triglyceride levels were significantly lower in hemodialysed patients compared to controls (1.29 +/- 0.5 mmol/l vs. 2.31 +/- 1.23 mmol/l, p < 0.0001). Serum leptin levels in hemodialysed patients correlated positively with body fat content, serum cholesterol and triglyceride levels. In the control group only the significant positive correlation with body fat content was found. In conclusion, this study demonstrated relatively higher serum leptin levels in hemodialysed patients compared to healthy subjects, although their nutritional status expressed by serum protein nutritional parameters and body fat content is significantly impaired. Except of the positive correlation with serum lipids levels no statistically significant relationships between serum leptin levels and biochemical nutritional parameters were found in our study.

Adipose Tissue↗

PubMed2000

[Serum leptin levels and soluble leptin receptors in female patients with anorexia nervosa].

BACKGROUND: Leptin action in peripheral tissues is enabled by an interaction with specific transmembrane receptors. Several of leptin receptor isoforms were identified, including soluble leptin receptor isoform structurally identical to extracellular domain of the the long leptin receptor isoform. The soluble receptor isoform is released to the circulation and acts probably as leptin-binding factor. The aim of our study was to measure serum concentrations of the soluble leptin receptor in patients with anorexia nervosa and in the control group of healthy women. Relationships of soluble leptin receptor levels to body mass index (BMI), body fat content, serum leptin, TNF-alpha and insulin levels were also studied. METHOD AND RESULTS: 16 patients with anorexia nervosa and 16 age-matched lean healthy women were included into the study. All of the subjects were measured and weighed, the body fat content was estimated from the skinfold thickness measurement. The blood for the determination of leptin, soluble leptin receptor and other hormonal parameters was obtained from all subjects after the overnight fasting. BMI, body fat content, serum leptin and insulin levels in patients with anorexia nervosa were significantly lower than in the control group (BMI: 14.98 +/- 2.32 vs. 22.21 +/- 2.48, p < 0.01, % fat content: 16.43 +/- 4.56 vs. 27.19 +/- 4.59, p < 0.01, leptin: 1.37 +/- 1.85 ng.ml-1 vs. 7.19 +/- 3.49 ng.ml-1, p < 0.01, insulin: 12.97 +/- 2.89 mU.l-1 vs. 17.09 +/- 5.57 mU.l-1, p < 0.05). Serum soluble leptin receptor levels in patients with anorexia nervosa were significantly higher compared the to control group (24.67 +/- 8.3 U.ml-1 vs. 15.71 +/- 2.79 U.ml-1, p < 0.01). No significant differences in serum TNF-alpha levels between the groups studied were found. Serum leptin levels in both groups correlated positively with BMI and body fat content. Serum soluble leptin receptor levels in both groups correlated negatively with BMI only. No statistically significant relationships between serum soluble leptin receptor levels and the rest of parameters studied were found in any of the groups studied. CONCLUSIONS: Serum soluble leptin receptors levels in patients with anorexia nervosa were significantly higher in comparison with the healthy subjects. Except of the negative correlation between serum soluble leptin receptor levels and BMI no statistically significant relationships between serum soluble leptin receptor and the rest of parameters studied were found.

Anorexia Nervosa↗

PubMed2000

Serum leptin levels in patients with hyperlipidemias.

Leptin is a protein hormone produced by adipocytes that reflects the body fat content. The aim of our study was to compare serum leptin levels in randomly selected untreated males and females with hypercholesterolemia and combined hyperlipidemia and in healthy control subjects matched for age and body mass index and to study the relations between leptin and serum lipids and lipoproteins. No statistically significant differences in serum leptin levels were found between the male control group (5.26 +/- 2.81 ng/mL(-1)) and the male group with hypercholesterolemia (8.16 +/- 3.85 ng/mL(-1)) or combined hyperlipidemia (7.51 +/- 4.83 ng/mL(-1)) and between the female control group (13.0 +/- 8.12 ng/mL(-1)) and the female group with hypercholesterolemia (15.36 +/- 8.89 ng/mL(-1)) or combined hyperlipidemia (18.63 +/- 10.15 ng/mL(-1)). Leptin concentration in male group with hypercholesterolemia did not differ significantly from the female control group; in the other male groups, leptin levels were significantly lower than those of the other female groups. Serum leptin levels in all studied groups except for the male group with hypercholesterolemia positively correlated with body mass index. Serum leptin levels correlated negatively with high-density lipoprotein cholesterol in the female group with hypercholesterolemia (r = -0.67, P < 0.01) and the male group with combined hyperlipidemia (r = -0.56, P < 0.01). A positive correlation between serum leptin and high-density lipoprotein cholesterol (r = 0.67, P < 0.01) and between leptin and lipoprotein (a) (r = 0.71, P < 005) was found in female group with combined hyperlipidemia. No other significant relationships between leptin and serum lipids or lipoproteins were found. We conclude that serum leptin levels in patients with hyperlipidemias do not significantly differ from those healthy control subjects matched by age and body mass index.

Adult↗

PubMed2000

Interaction between serum leptin levels and hypothalamo-hypophyseal-thyroid axis in patients with anorexia nervosa.

The main objective of the study was to evaluate the endocrinological picture of anorexia. Serum leptin levels are low in untreated anorexia nervosa (AN), but studies of the exact relationship between leptin, body weight and hormones of hypothalamo-hypophyseal-thyroid axis and the impact of refeeding in anorectics are limited. The sample consistent of 15 patients with anorexia nervosa before and 1 month after partial weight recovery, and 15 age-matched control subjects. The body mass index (BMI), leptin, plasma neuropeptide Y (NPY), serotonin, thyroxine (T4), triiodothyronine (T3) and reverse triiodothyronine (rT3) in serum were evaluated for each subject. The mean serum levels of leptin, T4, and T3 were significantly lower before weight recovery in 15 patients with AN than they were in control subjects. After partial weight recovery, basal T3 levels were unchanged and significantly lower than in controls. Basal T4 was even still more reduced, but we observed significantly elevated ratio of T3/T4 and reduced ratio rT3/T4 of in AN patients after gain recovery, indicating increased conversion of T4 to T3 than to rT3. The levels of serum leptin were low in AN, but after partial weight recovery slightly increased, and correlated with BMI. No differences were observed in serum NPY. Serum levels of IGF-1 and serotonin were lower in AN than in controls before and after partial weight gain. IGF-1 was slightly increased after partial weight gain. We did not find correlation between serum levels of leptin and serum T4. The low serum levels of T3 associated with chronic starvation were thought to be the result of impaired peripheral conversion of T4 to T3. However, decreased levels of T3 were still apparent even after a partial weight gain, and the concentration of T4 was even lower. The diminished serum level of TSH in AN, however, appeared to return to the level of controls. On the basis of these results, we assume that low serum levels of thyroid hormones in AN reflect a dysfunction of the HPT axis in AN patients. It is known that in man serum serotonin levels correlate positively with T3 levels. It is possible that the low serum levels of thyroid hormones in AN subjects result in low serum serotonin and its product, melatonin. While IGF-1 reflects the energy intake of the previous few weeks, the serum leptin concentration reflects the true status of the adipose stores, a fact that has useful clinical implications.

Anorexia Nervosa↗

PubMed2000

[Effect of physical activity on serum leptin levels].

Leptin is a protein hormone produced predominantly by adipocytes. Its serum concentrations usually reflect the total body fat content i.e. they are higher in obese than in lean subjects. The aim of our study was to follow the influence of the regular hard physical training on the serum leptin levels. Therefore, the serum leptin levels in top rugby players, top race walkers and age and gender-matched control group were compared. The relationship between serum leptin concentrations and body mass index and body fat content was also studied. It was found that serum leptin levels in rugby players were significantly higher than in race walkers group, but lower than in control one. Serum leptin levels in race walkers were lower than those of rugby players and of control group. The body fat content in race walkers was lower than in resting two groups. There was no significant difference in body fat content between control and rugby players group. Serum leptin levels correlated positively with body mass index and body fat content both in control and in rugby players group. No statistically significant relationship was found between leptin and body mass index or body fat content respectively in race walkers group. We conclude that serum leptin levels in top sportsmen are lower than in non-sporting healthy age and gender-matched controls. The lower leptin levels in top sportsmen are probably in part the result of lower body fat content and in part the result of complex neurohormonal adaptation on the long term physical training.

Adipose Tissue↗

PubMed2000

The regulation of adenohypophyseal prolactin secretion: effect of triiodothyronine and methylene blue on estrogenized rat adenohypophysis.

Estrogens and thyroid hormones contribute importantly to cell proliferation and tumor transformation in the pituitary gland. We found that methylene blue antagonized estrogen-promoted adenohypophyseal enlargement and the enhancement of prolactin secretion. The purpose of the present article is to provide a review about neurotransmitters and their receptors involved in estrogen-induced anterior pituitary growth and in the antagonistic effects of triiodothyronine (T3) and methylene blue (MB). Central dopaminergic and noradrenergic systems are the most important factors regulating pituitary growth and function. Recently nitric oxide (NO) was added to the list of the neurotransmitters and neuropeptides involved in the control of the anterior pituitary secretion. Our data suggest that estrogen-induced anterior pituitary growth is associated with decreased synthesis and metabolism of central catecholamines, reduction of adenohypophyseal beta-adrenergic receptors and increase of dopamine DA-2 receptors. We found that the treatment with T3 or MB prevented both estrogen-induced catecholaminergic inhibition and dopamine DA-2 receptor increment in the anterior pituitary. In contrast to T3, MB given alone also slightly decreased the anterior pituitary weight. Serum levels and anterior pituitary content of prolactin were increased after treatment with estradiol benzoate (EB), whereas T3 or MB partially attenuated prolactin hypersecretion after estrogen administration. This is in accord with the attenuation of EB-induced inhibition of dopaminergic system by T3 and MB. MB given in combination with EB also partially attenuated EB-promoted rise of adenohypohyseal NO synthase activity which plays an important role in the regulation of prolactin secretion. Further studies on central catecholaminergic systems, pituitary receptors, the nitrergic system and mechanisms of intracellular signal transduction are necessary for better understanding of pituitary tumor transformation and possibly for the discovery of new approaches towards treating patients with these diseases.

Adrenergic beta-Agonists↗