Stiff substrates inhibit collagen accumulation via integrin α2ß1, FAK and Src kinases in human atrial fibroblast and myofibroblast cultures derived from patients with aortal stenosis.

The aim of the study was to confirm whether cell substrate stiffness may participate in the regulation of fibrosis. The involvement of integrin α2ß1, focal adhesion kinase (FAK) and Src kinase in signal transmission was investigated. Human atrial fibroblasts and myofibroblasts were cultured in both soft (2.23 ± 0.8 kPa) and stiff (8.28 ± 1.06 kPa) polyacrylamide gels. The cells were derived from the right atrium of patients with aortal stenosis undergoing surgery. The isolated cells, identified as fibroblasts or myofibroblasts, were stained positively with α smooth muscle actin, vimentin and desmin. The cultures settled on stiff gel demonstrated lower intracellular collagen and collagen type I telopeptide (PICP) levels; however, no changes in α1 chain of procollagen type I and III expression were noted. Inhibition of α2ß1 integrin by TC-I 15 (10-7 and 10-8 M) or α2 integrin subunit silencing augmented intracellular collagen level. Moreover, FAK or Src kinase inhibitors increased collagen content within the culture. Lower TIMP4 secretion was reported within the stiff gel cultures but neither MMP 2 nor TIMP-1, 2 or 3 release was altered. The stiff substrate cultures also demonstrated lower interleukin-6 release. Substrate stiffness modified collagen deposition within the atrial fibroblast and myofibroblast cultures. The elasticity of the cellular environment exerts a regulatory influence on both synthesis and breakdown of collagen. Integrin α2ß1, FAK and Src kinase activity participates in signal transmission, which may influence fibrosis in the atria of the human heart.

Exendin-4 differentially modulates essential functions of human dermal fibroblasts under normoglycemic and hyperglycemic conditions.

Evidence that exendin-4, a glucagon-like peptide-1 analog, might be used to treat poorly healing wounds under diabetic and nondiabetic conditions has gained increasing interest. Little is known, however, about the effects of the drug on the production by dermal fibroblasts of key extracellular matrix and regulatory compounds. Therefore, we used human skin fibroblasts cultured in normo- (1 g/l = 5.6 mmol/l glucose) or hyperglycemic (4.5 g/l = 25 mmol/l glucose) culture medium to test the effects of exendin-4 (0 - 100 nmol/l) on fibroblast functions crucial for the wound healing process. Exendin-4 increased the proliferative and metabolic activities, as measured by the BrdU (bromodeoxyuridine) and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assays, respectively, of fibroblasts cultured in normoglycemic medium. Under hyperglycemic conditions, the drug had no effect on proliferation and reduced metabolic fibroblast activity. Exendin-4 decreased metalloproteinase-9 (MMP-9) secretion in the normoglycemic milieu only and increased tissue inhibitor of metalloproteinase-1 (TIMP-1) concentration in fibroblast colonies under both normo- and hyperglycemic experimental conditions. Exendin-4 increased the fibroblast growth factor-1 (FGF-1) concentration in cell colonies maintained in the normoglycemic milieu but decreased FGF-1 release when fibroblasts were grown in hyperglycemic medium. High glucose caused lactic dehydrogenase (LDH) leakage when compared with normoglycemic conditions, and exendin-4 was not able to prevent this effect, although it reduced LDH release from fibroblasts cultured in normoglycemic medium. Finally, exendin-4 increased glycosaminoglycan (GAG) content under both experimental conditions. Our results indicate that exendin-4 effects on the production of the extracellular matrix and regulatory proteins differ in human skin fibroblasts exposed to either normal or high glucose. In general, the beneficial effects of the drug, which may be important for the improvement of wound healing, are more pronounced under normoglycemic conditions, thus indicating that hyperglycemia attenuates the positive effects of exendin-4 on fibroblasts.

Disruption of histamine/H3 receptor signal reduces collagen deposition in cultures scar myofibroblasts.

A suitable inflammatory signal influences extracellular matrix accumulation and determines the quality of the myocardial infarction scar. The aim of the present study was to determine the influence of mast cell sonicates or histamine on collagen accumulation in heart myofibroblast culture and on the deposition of collagen in the myocardial infarction scar. The histamine receptor involved in the process was investigated. Myocardial infarction was induced by ligation of the left coronary artery. Myofibroblasts were isolated from the scar of myocardial infarction. The effects of mast cell sonicates, histamine and its receptor antagonists, i.e. ketotifen (H1-receptor inhibitor), ranitidine (H2-receptor inhibitor), ciproxifan (H3-receptor inhibitor), JNJ7777120 (H4-receptor inhibitor), imetit (H3 receptor agonist), were investigated. The mast cell sonicates or histamine (10-10 - 10-5M) augmented collagen content in myofibroblast cultures; however, histamine-induced elevation was reduced by ciproxifan (10-5M, 10-6M). Imetit (10-9 - 10-5M) elevated collagen content in the culture. H3 receptor expression on myofibroblasts was confirmed. Our findings indicate that histamine increases the deposition of collagen in cultures of myofibroblasts isolated from the myocardial infarction scar. This effect is dependent on H3 receptor activation.

The inhibitory effect of combination treatment with leptin and cannabinoid CB1 receptor agonist on food intake and body weight gain is mediated by serotonin 1B and 2C receptors.

Previous studies reported that the co-injection of leptin and cannabinoid CB1 receptor antagonists reduces food intake and body weight in rats, and this effect is more profound than that induced by these compounds individually. Additionally, serotonin mediates the effects of numerous anorectic drugs. To investigate whether serotonin interacts with leptin and endocannabinoids to affect food intake and body weight, we administered 5-hydroxytryptamine(HT)1B and 5-hydroxytryptamine(HT)2C serotonin receptor antagonists (3 mg/kg GR 127935 and 0.5 mg/kg SB 242084, respectively) to male Wistar rats treated simultaneously with leptin (100 µg/kg) and the CB1 receptor inverse agonist AM 251 (1 mg/kg) for 3 days. In accordance with previous findings, the co-injection of leptin and AM 251, but not the individual injection of each drug, resulted in a significant decrease in food intake and body weight gain. Blockade of the 5-HT1B and 5-HT2C receptors completely abolished the leptin- and AM 251-induced anorectic and body-weight-reducing effects. These results suggest that serotonin mediates the leptin- and AM 251-dependent regulation of feeding behavior in rats via the 5-HT1B and 5-HT2C receptors.

Hypoxia-related brain dysfunction in forensic medicine.

Blood gases levels imbalances belong to important factors triggering central nervous system (CNS) functional disturbances. Hypoxia can be illness-related, like in many COPD patients, or it may be caused by broad range of external or iatrogenic factors - including influence of drugs depressing respiration, failure to keep the patient's prosthesis-supported airways patent, or a mistake in the operation of medical equipment supporting patient's respiration. Hypoxia, especially when it is not accompanied by rapid carbon dioxide retention, can go unnoticed for prolonged times, deepening existing CNS disorders, sometimes rapidly triggering their manifestation, or evoking quite new conditions and symptoms - like anxiety, agitation, aggressive behavior, euphoria, or hallucinations. Those, in turn, often result in situations raising interest in law enforcement institutions which need forensic medicine specialist's assistance and opinion. The possibility of illness or drug-related hypoxia, especially in terminal patients, is used to raise questions about the patients' ability to properly express their will in the way demanded by law - it also must be considered as a factor limiting the patients' responsibility in case they commit crimes. The possibility of hallucinations in hypoxia patients limits their credibility as witnesses or even their ability to report crime or sexual abuse they have been subjected to.

Death as a result of violent asphyxia in autopsy reports.

Violent asphyxia can be subdivided into various kinds according to the mechanism, so that the resuscitation techniques are different in each case. The purpose of the present article was to analyze the autopsy reports of the Department of Forensic Medicine of the Medical University in Wroclaw, Poland of 2010, in which the established cause of death was violent asphyxia. We found that among the 890 autopsies performed, there were 164 cases of death due to violent asphyxia caused by drowning, choking on food, gastric fluid, or blood, hanging, manual strangulations, immobilization of the chest (positional asphyxia), environmental asphyxia due to substitution of the oxygen-rich air for some other gas, and others. The most common cause of death in the group was hanging, mostly suicidal hangings of alcohol-intoxicated males. Despite an early medical treatment consisting of removing the noose from the neck and suction the fluids from the mouth and bronchial tree to safe the central nervous system from imminent hypoxia, there were negative outcomes in most cases due to the development of critical brain ischemia, with deaths followed after several days spent in the intensive care units. No connection to gender or age of the deceased was noted. We conclude that violent asphyxia remains to be a quite commonly cause of death in the practice of forensic pathologists - among all the autopsies performed in 2010 every sixth was of an asphyxia victim.

Melatonin-induced glycosaminoglycans augmentation in myocardium remote to infarction.

Elevated levels of collagen as well as transient increases of glycosaminoglycans (GAG) have been shown in the myocardium remote to the infarction. The aim of the study is to observe the effect of melatonin on the accumulation of collagen and GAG in the left ventricle wall, remote to the infarction. A second aim is to determine whether the effect of the pineal indole is mediated by the membrane melatonin receptors of heart fibroblasts. Rats with myocardial infarction induced by ligation of the left coronary artery were treated with melatonin at a dose of 60 µg/100 g b.w. or vehicle (2% ethanol in 0.9% NaCl). The results were compared with an untreated control. In the second part of the study, the fibroblasts from the non-infarcted part of myocardium were isolated and cultured. Melatonin at a range of concentrations from 10(-8) M to 10(-6) M was applied to the fibroblast cultures. In the final part of the study, the influence of luzindole (10(-6) M), the melatonin membrane receptor inhibitor, on melatonin-induced GAG augmentation was investigated. Both collagen and GAG content were measured in the experiment. Melatonin elevated GAG content in the myocardium remote to the infarcted heart. Collagen level was not changed by pineal indoleamine. Fibroblasts isolated from the myocardium varied in shape from fusiform to spindle-shaped. Moreover, the pineal hormone (10(-7)M and 10(-6)M) increased GAG accumulation in the fibroblast culture. Luzindole inhibited melatonin-induced elevation of GAG content at 10(-6)M. Melatonin increased GAG content in the myocardium remote to infarction. This effect was dependent on the direct influence of the pineal indole on the heart fibroblasts. The melatonin-induced GAG elevation is blocked by luzindole, the melatonin membrane receptors inhibitor, indicating a direct effect of this indole.

Pharmacological doses of melatonin reduce the glycosaminoglycan level within the infarcted heart scar.

The aim of the study was to define the effect of pharmacological doses of melatonin, an agent known to be a scavenger of reactive oxygen species, on the extracellular matrix composition (glycosaminoglycans and collagen) in the infarcted heart scar. Rats were administered with melatonin at doses of 300 µg/100 g b.w. or 3 mg/100 g b.w. once daily (between 5:00 and 6:00 in the afternoon) or with 1.5 mg/100 g b.w. twice daily (between 8:00 and 9:00 in the morning and additionally between 5:00 and 6:00 in the afternoon). The levels of collagen, glycosaminoglycans (GAG) and some oxidative stress markers (lipid oxidation, the content of sulphydryl groups in proteins and glutathione) were evaluated. In the second part of the experiment, cells were isolated from the scar, identified as myofibroblasts, cultured and treated with melatonin at concentrations ranging from 10⁻7 M to 10⁻¹° M. The pineal indoleamine was seen to reduce the GAG content of the scar, while the collagen content of the scar remained unchanged. A 10⁻7 M concentration of melatonin caused an increase in the GAG level in the myofibroblast cultures, while lower concentrations (10⁻8 M-10⁻¹° M) of pineal indoleamine were not effective. Melatonin decreased lipid oxidation and increased the sulphydryl groups of total proteins and glutathione, which suggests its antioxidative activity in the applied doses. The present study shows that pharmacological doses of melatonin reduce the GAG level in an infarcted heart scar. Since the mechanism of GAG content reduction cannot be explained by direct action of the pineal indoleamine on myofibroblasts in the myocardial infarction scar, we hypothesise that changes in GAG content could be indirectly induced by melatonin, that is caused by changes in regulatory systems or reduction of the inflammatory reaction in the area of the infarction. In addition, this paper shows that long-term treatment with melatonin of rats affected by myocardial infarction may reduce oxidative stress in the infarction area.

Experimental hypothyroidism increases content of collagen and glycosaminoglycans in the heart.

The connective tissue matrix of the heart remains under regulatory influence of the thyroid hormones. Some conflicting data describe the connective tissue changes in subjects with thyroid gland disorders. The aim of the study was to assess the changes of the connective tissue accumulation in the heart of rats in the state of hypothyroidism and to answer the question whether TSH is involved in mechanism of the observed phenomena. Hypothyroidism in rats was induced by methylotiouracil treatment or by thyreoidectomy. The thyroid hormones [freeT3 (fT3), freeT4 (fT4)] and pituitary TSH were measured in plasma with radioimmunological method. The glycosaminoglycans (GAG) and total collagen were measured in heart muscle of both left and right ventricles. Cells from the rat's heart were isolated and cultured. The cells were identified as myofibroblasts by electron microscopy method. The effects of TSH in concentrations ranging from 0.002 to 20 mIU/ml, on connective tissue accumulation in heart myofibroblasts cultures were tested. The primary hypothyroidism was developed both in groups with thyroidectomy and with methylthiouracil. The levels of fT3 and fT4 both in rats with thyreoidectomy and animals treated with methylthiouracil were decreased and TSH level in these two experimental groups was elevated. In the heart of the rats with experimental hypothyroidism increased content of both GAG and collagen was found. Myofibroblast number in culture was increased by TSH. Regardless of the method of its induction, hypothyroidism increased collagen and GAG contents in the heart. TSH is not involved in regulation of collagen and glycosaminoglycans accumulation in the heart of rats affected with primary hypothyroidism.

Effects of neuraminidase on apoptosis of blood lymphocytes in rats with implanted Morris tumor.

In this study we examined the influence of neuraminidase on apoptosis of peripheral blood lymphocytes in rats with an implanted Morris tumor. The main objectives of the study were to determine whether the percentage of apoptotic blood lymphocytes would depend on the dosing regimen of neuraminidase and whether neuraminidase would affect caspase-3 activity, a marker of the apoptosis, in blood lymphocytes. A total of 51 rats were used for the study. In three groups, totalling 39 animals, Morris tumor was implanted and neuraminidase was injected intravenously using two dosing regimens: 10 units three times on Day 4, Day 7, and Day 14 and 5 units as a single dose on Day 4 of the experiment or was skipped (control). The remaining 12 rats constituted a reference group of healthy animals. At the end of the experimental period on Day 21, blood was drawn from the heart, and mononuclear cells were separated and cultured. Apoptosis of blood lymphocytes was assessed in cell cultures from fluorescence spectra generated by a Sybr Green I dye forming bonds with nuclear DNA. Caspase-3 activity was measured colorimetrically in homogenates of lymphocyte cultures using a CASP-3-C kit (Sigma, St. Louis, MO). On the whole, the results demonstrate that the bigger, but not the smaller, dose of neuraminidase was markedly effective in preserving the vitality of blood lymphocytes and in decreasing both the number of apoptotic lymphocytes and capsase-3 activity in the rats with Morris tumor. Neuraminidase treatment failed, however, to lessen the tumor size. In conclusion, the study demonstrates that neuraminidase caused an appreciable decline in apoptosis of blood lymphocytes in rats with the Morris tumor; the effect was dose-dependent. Although neuraminidase failed to influence the local cancer development in terms of tumor size, its anti-apoptotic effect toward the cells of the immune system of a cancer host is of research interest as it may potentially offer a way to strengthen the host's immune response.

Comparison of a statin vs. hypolipemic diet on the oxidant status in hemodialyzed patients with chronic renal failure.

Hemodialyzed patients with chronic kidney disease are prone to atherosclerosis, which occurs due mainly to lipid abnormalities. Abnormal lipid metabolism could result, among others, from increased formation of free radicals and, consequently, oxidative stress in these patients. The objective of the present study was to evaluate the influence of therapy with lovastatin or with a hypolipemic diet only on oxidative stress in hemodialyzed patients. We addressed the issue by measuring the total antioxidant status (TAS) and the level of 8-hydroxy-2-deoxyguanosine (8-OHdG), an oxidative DNA damage metabolite, in the serum. The study group consisted of 71 patients. They were divided into 3 groups: treated with lovastatin (20 mg/day, n=30), with a hypolipemic diet alone (n=28), and untreated controls (n=13). Serum levels of TAS and 8-OHdG (8-hydroxy-2-deoxyguanosine) were determined. Blood samples were collected at the beginning of the study and then after a 6 months' therapy. We found that the level of 8-OHdG decreased considerably only in the lovastatin-treated group; the decrease was from 15.6+/-8.1 to 12.5+/-4.8 ng/ml (P=0.04). In the other two groups changes in 8-OHdG were insignificant. The level of TAS increased significantly in the lovastatin-treated group from 1.28+/-0.20 to 1.37+/-0.116 mmol/l (P=0.011), decreased in the diet-treated group from 1.55+/-0.14 to 1.45+/-0.11 mmol/l (P=0.007), and remained unchanged in the untreated group (1.42+/-0.11 vs. 1.40+/-0.12 mmol/l). We conclude that lovastatin, but not a hypolipemic diet alone, exerts an antioxidant effect in hemodialyzed patients. However, the determinants of the antioxidant effect of statins in patients with chronic renal failure are unclear and their resolution would require alternative study designs.

What influences the level of oxidative stress as measured by 8-hydroxy-2'-deoxyguanosine in patients on hemodialysis?

Oxidative stress is at play in the progression of chronic renal failure (CRF) and in the genesis of atherosclerosis. The aim of the present study was to evaluate the factors that might influence the oxidative-antioxidative balance in patients on hemodialysis. The study group consisted of 71 hemodialysis patients due to CRF. Sixteen healthy subjects constituted a control group. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), C-reactive protein (CRP), and the blood lipid profile were measured in both groups. The results showed significantly higher mean levels of both 8-OHdG and CRP in the hemodialysis patients compared with that in the control subjects. The highest level of 8-OHdG was found in the subgroups of the patients with CRF primarily caused by diabetes (16.4 ng/ml) and with hypertensive nephropathy (15.8 ng/ml). More than a 2.5-fold higher level of 8-OHdG in the hemodialysis patients compared with the control subjects points to the presence of intensive oxidative stress in the patients.

Temporary augmentation of glycosaminoglycans content in the heart after left coronary artery ligation.

Introduction: Augmentation of glycosaminoglycans (GAG) in various tissues after injury is well known, however, there is no information about the metabolism of GAG during the heart remodeling after infarction. The study is focused on the changes of total GAG concentrations in the viable myocardium and scar after experimental left coronary artery occlusion. To shed some light on the possible mechanism of the changes, GAG were also evaluated in the skin. Methods: Male Wistar rats were subjected to left coronary artery ligation or to sham operation. After 3, 6 or 12 weeks of follow up the rats were sacrificed and the heart and skin were collected. The heart was cut into parts: right ventricle, septum, viable region of left ventricle and scar. The Farndale method was used for the estimation of GAG in the samples. Results: High level of GAG in the myocardial scar tissue was seen in the 3 weeks of follow up and reached maximum in the 6 weeks and then decreased in week 12. Similar pattern of GAG changes was found in the contractile part of the heart. In both viable part of the left ventricle and septum the peak level of GAG was found in rats 6 weeks after the onset of infarction. Than the content of GAG decreased towards the control level. There was no alteration in the GAG content in the skin and a wall of the right ventricle. Conclusion: Temporary augmentation of GAG content is present not only in myocardium directly injured by ischaemia but also in the viable part of the heart subjected mainly to increased haemodynamic stresses. The local nature of mechanisms responsible for the GAG changes has been postulated.

Vasopressin and oxytocin release and the thyroid function.

The aim of the present investigations was to examine the effects of the states of hypothyroidism or hyperthyroidism on vasopressin (AVP) and oxytocin (OT) release under conditions of equilibrated water metabolism as well as of osmotic stimulation, brought about by the dehydration or hypertonic saline administration. The euhydrated and simultaneously hypothyroid rats showed decreased hypothalamic AVP and OT content and somewhat higher but not significant neurohypophysial AVP content. In these animals the raised OT (but not AVP) plasma level has been observed. In hyperthyroid rats drinking tap water ad libitum the neurohypophysial AVP and OT content significantly diminished; plasma OT concentration (but not AVP) was then elevated. The state of osmotic stimulation was the reason of different response of the hypothalamo-neurohypohysial system function in hypo- or hyperthyroid rats. Significant decreases of neurohypophysial AVP and OT content were found in both hypothyroid dehydrated as well as hypothyroid hypertonic saline-treatment rats as compared with hypothyroid euhydrated ones. On the contrary, in the state of hyperthyroidism AVP content in the neurohypophysis distinctly raised in dehydrated and salt-loaded rats; in these last neurohypophysial OT content increased as well. Plasma OT (but not AVP) distinctly diminished in hyperthyroid and simultaneously dehydrated or hypertonic saline injected rats in relation to hyperthyroid control subgroup. Data from the present study suggest that: 1). altered thyroid gland function affects vasopressin and oxytocin release from the hypothalamo-neurohypophysial system in the state of equilibrated water metabolism; 2). the state of hypo- or hyperthyroidism modifies the response of AVP-ergic and OT-ergic neurons upon the osmoreceptors/osmodetectors stimulation. It may be supposed that OT-ergic neurons display greater than AVP-ergic neurons sensitivity upon the thyroid hormone influence.

[Genetically modified organisms--problems and legislation]. / Geneticky modifikované organizmy--problémy a legislativa.

Genetically modified organisms are defined by law as entities capable of replication and/or transmission of hereditary material that had been altered by the insertion or removal of a DNA fragment. By the EU legal regulation as well as by the Czech law, such organisms are considered risky whereas other products of breeding, though obtained by, e.g., induced mutagenesis, are claimed as safe. Organisms transferred from other ecosystems are also considered safe. The Czech law on the use of genetically modified organisms is based on registers of users and organisms for specific use. Application for the registration that is valid as an approval should be submitted to the Ministry of Environment. The applicant is obliged to present the risk assessment of the particular use of genetically modified organisms. Genetically modified organisms are connected with certain risk to ecology, however health risks are brought about almost exclusively by microorganisms. Modified organisms used for food production are thoroughly tested for substantial equivalency with standard crops and with respect to health parameters of the protein(s) newly introduced due to genetic modification. Detail tests as well as their cost are close to the testing of new drugs. European as well as Czech rules for food labelling are motivated by the psychology of consumers rather than by health impact. They result to absurdities but do not meet the task of public psychology. This is why the EU authorities are looking for measures to change the present situation that other wise would bring Europe well behind the developed countries.

Response of aorta connective tissue matrix to injury caused by vassopressin-induced hypertension or hypercholesterolemia.

The aim of the study was to investigate the effect of two various atherogenic stimuli (vasopressin-induced hypertension or hypercholesterolemia) on the collagen and glycosaminoglycan (GAG) content in the internal or external part of both thoracic and abdominal aorta, which are differently susceptible to atherosclerosis. Experimental rabbits were divided into four groups: controls, animals injected with physiological saline or vasopressin at the dose of 1 IU/kg from the 1 st to the 25 th day of experiment, respectively. The animals from group 4 were maintained on food, containing 0.25% cholesterol. Only in the vasopressin-treated group, the systolic blood pressure was elevated from 110 mmHg at the beginning, to 166 mmHg at the end of the study. After 14 weeks the aorta was dissected into internal and external parts. GAG fractions were separated and estimated as uronic acids. Collagen was evaluated as the hydroxyproline content in the tissue. Augmented total GAG and heparan sulphate (HS) level, plus no changes in the collagen content were seen in the internal part of the thoracic aorta in rabbits with hypercholesterolemia or hypertension. In the hypertensive animals, the changes were extended to the external part of the aorta and, additionally, comprised the elevation of the chondroitin-4 sulphate (C-4S) content. The two atherogenic stimuli increased the collagen level with no elevation of the GAG content in the abdominal aorta. A convergent effect of the injury, caused by hypertension or hypercholesterolemia on the collagen, total GAG and HS content was shown in the respective parts of the rabbit aortas. The common GAG, increased in the thoracic aorta, stand for the HS, in both hypertensive and hypercholesterolemic rabbits. As the sensitivity to atherosclerosis development in different segments of the aorta varies, they express various responses of the connective tissue matrix to injuries, caused by hypertension or hypercholesterolemia.

Pinealectomy-induced elevation of collagen content in the intact skin is suppressed by melatonin application.

The pineal gland is involved in wound repair and collagen deposition in sponge-induced granulomas. The aim of this investigation was to discover whether the pineal gland was able to regulate collagen accumulation in the intact skin. Wistar rats were divided into five groups: control, sham-operated with vehicle application, sham-operated with melatonin injections (30 micrograms/100 g body wt), pinealectomized with vehicle, and pinealectomized with melatonin supplementation. After 8 weeks, the collagen content was estimated as hydroxyproline concentration in the dry tissue of the skin. The results showed that melatonin markedly (p < 0.001) reduced collagen accumulation in the skin. Pinealectomy enhanced collagen deposition in the skin (p < 0.02) and melatonin application reduced the pinealectomy-induced elevation of collagen content (p < 0.001). Results clearly indicate that collagen accumulation in the intact skin is under the control of the pineal gland, and that melatonin, the pineal hormone, is responsible for this control.

Effect of pinealectomy and melatonin on vasopressin-potentiated passive avoidance in rats.

The pineal indoleamine, melatonin, and the hypothalamic neuropeptide, vasopressin, facilitate passive avoidance behaviour in rats. The similarity of the effects suggest that interaction might occur between the two substances. Therefore, the effect of intraperitoneally applied vasopressin and/or melatonin on one-trial learning passive avoidance behaviour was studied in pinealectomized rats. Intraperitoneal treatment with 500 ng vasopressin 1 hr before the retention test increased passive avoidance latency of sham-operated rats. In pinealectomized rats, an identical amount of vasopressin was ineffective. In sham-operated rats, melatonin blocked the effect of vasopressin. It is concluded that vasopressin needs a regulated pineal function for developing effects in passive avoidance behaviour.

Melatonin suppresses the pinealectomy-induced elevation of collagen content in a wound.

The pineal gland hormone was shown to be involved in the regulation of repair and connective tissue accumulation in a wound. The hypothesis that melatonin injection could reverse the pinealectomy-induced elevation of the collagen content in scar tissue was verified. The effect of various melatonin doses (3, 30 and 100 micrograms/100 g body wt) on soluble, insoluble and total collagen content in the granulation tissue of a wound was investigated. The collagen level was estimated in pinealectomized rats, as well as in pinealectomized animals treated with melatonin. Ivalon sponges inserted subcutaneously were applied as a wound model. After 4 weeks the collagen content was measured as a hydroxyproline concentration in the dry tissue of the wound. The results showed that melatonin at the dose of 30 micrograms/100 g body wt significantly decreased both total and insoluble collagen content in the wounded tissue (p < 0.05), but other doses were ineffective. Pinealectomy increased the total (p = 0.05) and insoluble collagen level (p < 0.05) in the granulation tissue. Melatonin suppressed pinealectomy-induced elevation of the total and insoluble collagen content in the wounds (p < 0.05). No influence of the pineal gland on the soluble collagen content was observed. The results showed that melatonin was involved in the inhibitory control of the collagen content.

[Glycosaminoglycans in the peritoneal fluid of infertile women with endometriosis]. / Glykosaminoglykany v peritoneální tekutine u neplodných zen s endometriózou.

The authors examined the glycosaminoglycan level in the peritoneal fluid of 54 infertile women with or without endometriosis. The peritoneal fluid was collected during a routine laparoscopic examination. Glycosaminoglycans were assayed in complexes with Alcian blue. There was a higher concentration of glycosaminoglycans in peritoneal fluid during the follicular phase of women with endometriosis. The authors did not prove a statistically significant difference between women with and without endometriosis.