Robert Zbucki

Cannabinoids enhance gastric X/A - like cells activity

It has been reported that cannabinoids may cause overeating in humans and in laboratory animals. Although, endogenous cannabinoids and their receptors (CB1) have been found in the hypothalamus, and recently also in gastrointestinal tract, the precise mechanism of appetite control by cannabinoids remains unknown. Recently, ghrelin--a hormone secreted mainly from the stomach X/A-like cells was proposed to be an appetite stimulating agent. The aim of this study was the evaluation of the influence of a single ip injection of a stable analogue of endogenous cannabinoid--anandamide, R-(+)-methanandamide (2.5 mg/kg) and CP 55,940 (0.25 mg/kg), an exogenous agonist of CB1 receptors, on ghrelin plasma concentration and on ghrelin immunoreactivity in the gastric mucosa of male Wistar rats. Four hours after a single injection of both cannabinoids or vehicle, the animals were anaesthetized and blood was taken from the abdominal aorta to determinate plasma ghrelin concentration by RIA. Subsequently, the animals underwent resection of distal part of stomach. Immunohistochemical study of gastric mucosa, using the EnVision method and specific monoclonal antibodies against ghrelin was performed. The intensity of ghrelin immunoreactivity in X/A-like cells was analyzed using Olympus Cell D image analysis system. The attenuation of ghrelin-immunoreactivity of gastric mucosa, after a single injection of R-(+)-methanandamide and CP 55,940 was accompanied by a significant increase of ghrelin plasma concentration. These results indicate that stimulation of appetite exerted by cannabinoids may be connected with an increase of ghrelin secretion from gastric X/A-like cells.

The influence of laparoscopic adjustable gastric banding and laparoscopic sleeve gastrectomy on weight loss, plasma ghrelin, insulin, glucose and lipids

The aim of this study was to assess the impact of laparoscopic gastric banding and laparoscopic sleeve gastrectomy on the concentration of ghrelin, insulin, glucose, triglycerides, total and HDL-cholesterol, as well as AST and ALT levels in plasma in patients with obesity. The research includes 200 patients operated using LAGB (34 men average age 37.0 ± 12.6 years and 66 women average age 39.18 ± 12.17 years) and LSG (48 men average age 47.93 ± 9.24 years and 52 women, 19 ± 9.33 years). The percentage of effective weight loss, effective BMI loss, concentration of ghrelin, insulin, glucose, triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol, ALT, AST and HOMA IR values was taken preoperatively and at 7th day, 1 month, 3 and 6 months after surgery. Both after LSG and after LAGB, statistically significant reduction in BMI, serum insulin, glucose and HOMA IR was noticed in comparison to the preoperative values. Post LAGB, patients showed an increase of ghrelin, while LSG proved ghrelin decreased. Correlations between glucose and BMI loss, and between insulin and BMI loss in both cases are more favorable in the LSG group. Lipid parameters, AST and ALT have undergone declines or increases in the particular time points. Both techniques cause weight loss and this way lead to changes in the concentration of ghrelin, as well as to the improvement of insulin, glucose, cholesterol and triglycerides metabolism. They reduce metabolic syndrome and multiple comorbidities of obesity.

The activity of gastric ghrelin positive cells in obese patients treated surgically

Ghrelin is a 28 amino acid peptide hormone regulating food intake and stimulating releasement of growth hormone. It is produced in a distinct endocrine call known as X/A - like cells. The most abundant source of this very important factor in energy homeostasis is gastric fundus. Regulatory mechanisms of ghrelin synthesis and secretion in physiological and pathological states are not discovered completely. The aim of our study was evaluation of the activity of gastric X/A-like cells in obese patients before and after the most popular surgical bariatric procedures - Roux - Y Gastric Bypass (RYGB) and Laparoscopic Adjustable Gastric Banding (LAGB). Obese patients in number 18 took part in the study. LAGB was performed in 7 patients and RYGB in 11 patients. Peripheral blood was taken from each patient before operation and first day, seventh day, one month and three months after surgery. Ghrelin level was determined by RIA technique. The specimen of stomach was taken from circular stapler after gastrojejunostomy during RYGB and immunohistochemical study of gastric mucosa, using the EnVision method and specific monoclonal antybodies against ghrelin was performed. The intensity of ghrelin-immunoreactivity in X/A-like cells was analyzed using Olympus Cell D image analysis system. Efficiency of bariatric procedures was estimated by EWL- excess weight loss. We observed very strong immunohistochemical reactions of gastric X/A-like cells, accompanied by lower ghrelin plasma concentration, in comparison to the control group. LAGB procedure induced increase of ghrelin plasma level while RYGB procedure induced decrease of this hormone. The main finding of the present study is the hypoactivity of gastric X/A-like cells in obese patients in comparison to the control group.

Estrogens modulate RANKL-RANK/osteoprotegerin mediated interleukin-6 effect on thyrotoxicosis-related bone turnover in mice.

Interleukin-6 has been shown to cause imbalance between bone resorption and formation in thyrotoxicosis. The aim of the present study was an attempt to estimate the influence of estrogens on thyrotoxicosis-related disturbances in bone turnover in relation to RANKL-RANK/osteoprotegerin system in IL-6 deficient mice. The study was performed on 56, 12-13 weeks old, female mice: C57BL/6J (wild-type; WT) and C57BL/6J (IL6-/-Kopf) (IL-6 knock-out; IL6KO). The mice were randomly divided into 8 groups with 7 mice in each one: 1. WT controls, 2. IL6KO controls, 3. WT mice with thyrotoxicosis, 4. IL6KO mice with thyrotoxicosis, 5. WT ovariectomized, 6. IL6KO ovariectomized, 7. WT ovariectomized mice with thyrotoxicosis, and 8. IL6KO ovariectomized mice with thyrotoxicosis. Experimental model of menopause was evoked by bilateral ovariectomy carried out in 8-9 weeks old mice. Thyrotoxicosis was induced by intraperitoneal injection of levothyroxine at a dose of 1 μg/g daily over 21 days. The serum levels of TRACP5b, osteocalcin, OPG, and RANKL were determined by ELISA. RANKL serum concentrations were elevated significantly in all groups of ovariectomized mice as compared to respective controls, however, in a minor degree in IL6KO thyrotoxic mice as compared to wild-type animals. Osteoprotegerin serum levels were significantly increased in all thyrotoxic groups of mice except ovariectomized IL6KO animals. To sum up, the results of the present study suggest that IL-6 plays a key role in stimulation of RANKL-RANK/OPG system and this effect is strongly enhanced in conditions of accelerated bone turnover such as thyrotoxicosis and/or estrogen depletion.

Estimation of gastric ghrelin-positive cells activity in hyperthyroid rats

Ghrelin is a peptide of 28 amino acids that transmits appetite related signals from peripheral organs to the brain. The main source of ghrelin is stomach. The regulation of ghrelin secretion is still unknown. The finding that fasting and food intake, respectively increase and decrease the secretion of ghrelin suggests that this hormone may be a bridge connecting somatic growth with energy metabolism and appears to play an important role in the alteration of energy homeostasis and body weight in pathophisiological conditions. The purpose of this study was the evaluation of gastric ghrelin immunoreactivity and ghrelin plasma concentration in male Wistar rats with hyperthyroidism. Experimental model of hyperthyroidism was induced by intraperitoneal injection of levothyroxine at the dose of 80 microg/kg daily over 21 days. At the end of experiment the animals were anaesthetized, blood was taken from abdominal aorta to determinate plasma ghrelin concentration by RIA and then the animals underwent resection of distal part of stomach. Immunohistochemical study were performed using monoclonal specific antybodies against ghrelin. Hyperthyroidism was a reason of increase of gastric mucosal ghrelin - immunoreactivity, accompanied by a significant decreased of ghrelin plasma concentration. Those observations may indicate, that chronic administration of L-thyroxine cause the change of ghrelin plasma concentration in rats, probably via direct influence on gastric X/A-like cells, but this effect is not responsible for hyperphagia associated with hyperthyroidism.

Role of interleukin-6 on RANKL-RANK/osteoprotegerin system in hypothyroid ovariectomized mice.

Postmenopausal women frequently develop hypothyroidism. Estrogen depletion is accompanied by an increase of IL-6, accelerating bone turnover. The influence of hypothyroidism on bone metabolism in postmenopausal women is poorly understood. The aim of the study was an attempt to clarify the role of interleukin-6 on RANKL-RANK/osteoprotegerin system in hypothyroid ovariectomized mice. The study was performed on 56, 12-13 weeks old, female mice: C57BL/6J (wild-type; WT) and C57BL/6JIL6-/-Kopf (IL-6 knock-out; IL6KO). The mice were randomly divided into 8 groups with 7 mice in each one: 1/ WT controls, 2/ IL6KO controls, 3/ WT hypothyroid mice, 4/ IL6KO hypothyroid mice, 5/ WT ovariectomized, 6/ IL6KO ovariectomized, 7/ WT ovariectomized hypothyroid mice and 8/ IL6KO ovariectomized hypothyroid mice. Experimental model of menopause was produced by bilateral ovariectomy carried out in 8-9 weeks old mice. Experimental model of hypothyroidism was induced by propylthiouracyl administration in driking water. The serum levels of TRACP 5b, osteocalcin, OPG and RANKL were determined by ELISA. Serum RANKL concentrations were elevated significantly in all groups of ovariectomized mice as compared to respective controls, but in a minor degree in IL6KO hypothyroid mice as compared to wild-type animals. Moreover sRANKL values were significantly lower in IL6KO as compared to WT controls and IL6KO PTU injected mice. Osteoprotegerin serum levels were decreased in all IL-6 deficient mice and in a highest degree in sham-operated hypothyroid mice. To sum up, the results of the present study suggest that estrogens deficit is a strong stimulus for RANKL-RANK/OPG pathway that breaks an inhibitory influence of hypothyroidism even in IL-6 deficient mice.

Dynamics of cocaine- and amphetamine-regulated transcript containing cell changes in the adrenal glands of two kidney, one clip rats

Taking into consideration the homeostatic disorders resulting from renal hypertension and the essential role of cocaine- and amphetamine-regulated transcript (CART) in maintaining homeostasis by regulating many functions of the body, the question arises as to what extent the renovascular hypertension affects the morphology and dynamics of changes of CART-containing cells in the adrenal glands. The aim of the present study was to examine the distribution, morphology, and dynamics of changes of CART-containing cells in the adrenal glands of “two kidney, one clip” (2K1C) renovascular hypertension model in rats. The studies were carried out on the adrenal glands of rats after 3, 14, 28, 42, and 91 days from the renal artery clipping procedure. To identify neuroendocrine cells, immunohistochemical reaction was performed with the use of a specific antibody against CART. It was revealed that renovascular hypertension causes changes in the endocrine cells containing CART in the adrenal glands of rats. The changes observed in the endocrine cells depend on the time when the rats with experimentally induced hypertension were examined. In the first period of hypertension, the number and immunoreactivity of CART-containing cells were decreased, while from the 28-day test, it significantly increased, as compared to the control rats. CART is relevant to the regulation of homeostasis in the cardiovascular system and seems to be involved in renovascular hypertension. The results of the present work open the possibility of new therapeutic perspectives for the treatment of arterial hypertension, since CART function is involved in their pathophysiology.