Intracerebroventricular salusin-ß infusion to rats increases hypothalamus-pituitary-testicular axis hormones.

Salusin-ß (Sal-ß), which originates from preprosalusin, is a multifunctional hormone with a peptide structure. Sal-ß exists in the hypothalamus and can stimulate the pituitary gland. The present study was conducted to determine the effects of Sal-ß on hormones that play roles in the male reproductive system. Forty male Wistar Albino rats were used in the study. No infusions were performed on the control group, and infusions were applied to the infusion groups (artificial cerebrospinal fluid to the sham group, 2 and 20 nM Sal-ß to the experimental group) through intracerebroventricular infusion for 7 days at 10 µl/hour rate. The animals were decapitated after 7 days of infusion; and the hypothalamus, testicles, and blood tissue samples were collected. The gonadotropin-releasing hormone (GnRH) mRNA levels were determined from the hypothalamus tissues by using the Real Time-PCR Method, and the serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone levels were determined using the ELISA method. Also, Hematoxylin-Eosin Staining Method was used for histopathological evaluations in the testicle tissues. As a result, Sal-ß infusion increased GnRH mRNA levels in hypothalamus tissues (p < 0.05) besides, serum LH, FSH, and testosterone levels of the rats were higher at significant levels following Sal-ß infusion compared to the control and sham group (p < 0.05). In the histological examination of the testicle tissues, Sal-ß application was found to decrease the seminiferous tubule diameter and germinal epithelial thickness (p < 0.05). This evidence is the first, indicating that Sal-ß, which is administered to male rats with central infusion, stimulates hypothalamus and pituitary tissues, and causes increased secretion of male reproductive hormones.

Phytochemical compounds and antiradical, antimicrobial, and cytotoxic activities of the extracts from Hypericum scabrum L. Flowers.

Hypericum scabrum L. has been widely used in traditional medicine for the treatment of many diseases just as the other Hypericum species. In the present study, the antiradical, antimicrobial and cytotoxic activities of water and ethanol extracts of H. scabrum flowers were investigated. Their phytochemical contents and composition were also determined. The water and ethanol extracts are better scavenged ABTS (97.89 and 98.99%) and OH radicals (96.36 and 97.33%); the water extract is better scavenged DPPH radicals (91.66%) than the standard antioxidant BHA (94.33, 85.19, 90.16%, respectively). Flowers of H. scabrum contain flavonoids, phenolic acids, vitamins and phytosterols, dominated by catechin, vanillic acid, vitamin K and ergosterol. The extracts exhibit a strong cytotoxic activity against MCF-7, HCT-116, and LNCaP cancer cell lines. It is found that their antimicrobial activities are higher than the standard antibiotics. These results indicate that H. scabrum flowers have potent antiradical, antimicrobial and cytotoxic activities.

Bioactive contents, In vitro antiradical, antimicrobial and cytotoxic properties of rhubarb (Rheum ribes L.) extracts.

Rheum ribes L. (rhubarb) is belonging to Polygonaceae, and its roots and fresh shoots are consumed as vegetable in Turkey. This plant is considered to be one of the most important pharmaceutical raw materials in Middle East. In this study, the antiradical, antimicrobial, cytotoxic and bioactive properties of water, ethanol, and methanol extracts of R. ribes stems were determined. R. ribes stems water, ethanol and methanol extracts are better scavenged ABTS•+ (99.27, 99.91, and 99.88%), DPPH• (83.11, 81.42, and 83.26%), and OH• radicals (93.49, 94.21, 95.86%) than standard antioxidant BHA (95.32, 80.49, and 93.78%). Stems of R. ribes abundantly include bioactive compounds, dominated by rutin, catechin, caffeic acid, ferulic acid, α-tocopherol and vitamin D. These extracts show effective cytotoxic properties against PC-3, A2780, HCT-116 and MCF-7 cancer cell lines at 24h. It is found that R. ribes contain high amount important bioactive contents, and has effective antiradical and cytotoxic properties.

Central irisin administration suppresses thyroid hormone production but increases energy consumption in rats.

Irisin, which is secreted from the skeletal muscle in response to physical exercise and defined as a thermogenic peptide, may play an important role in energy metabolism. Thyroid hormones, which are one of the other influential factors on the metabolic status, increase heat production and are the main regulators of energy metabolism. This study was conducted to determine the possible effects of irisin administration on thyroid hormones. Forty adult male Wistar albino rats were used in the study. The rats were equally divided into 4 groups (n = 10). The brain infusion kit was implanted in the groups, and irisin (or solvent as control) was centrally administered to the rats via osmotic mini pumps for 7 days. During the experiment, food consumption, body weights, and body temperatures of the animals were recorded. Food intake was significantly increased in the groups treated with irisin (p < 0.05), but their body weights were not changed. Hypothalamic TRH gene expression, serum TSH, fT3, and fT4 levels were significantly lower in the groups treated with irisin as compared to the naive and control groups (p < 0.05). In addition, irisin increased UCP1 mRNA expression in white and brown adipose tissue and UCP3 mRNA expression in muscle tissue in rats and also raised their body temperature (p < 0.05). Consequently, although central irisin administration has inhibitory effects on the hypothalamic-pituitary-thyroid axis, it seems to be an important agent in the regulation of food intake and energy metabolism.

Effects of central FGF21 infusion on the hypothalamus-pituitary-thyroid axis and energy metabolism in rats.

The aim of this study was to evaluate the impact of intracerebroventricular chronic fibroblast growth factor 21 (FGF21) infusion on hypothalamic-pituitary-thyroid (HPT) axis, energy metabolism, food intake and body weight. Thirty male Wistar albino rats were used and divided into three groups including control, sham (vehicle) and FGF21 infused groups (n = 10). Intracerebroventricularly, FGF21 and vehicle groups were infused for 7 days with FGF21 (0.72 µg/day) and artificial cerebrospinal fluid, respectively. During the experimental period, changes in food intake and body weight were recorded daily. Serum thyroid stimulating hormone (TSH), Triiodothyronine (T3) and thyroxine (T4) levels were measured using ELISA. TRH and uncoupling protein 1 (UCP1) gene expressions were analyzed by using RT-PCR in hypothalamus and adipose tissues, respectively. Chronic infusion of FGF21 significantly increased serum TSH (p < 0.05), T3 (p < 0.05) and T4 (p < 0.001) levels. Additionally, hypothalamic TRH (p < 0.05) and UCP1 gene expressions (p < 0.05) in white adipose tissue were found to be higher than in the vehicle and control groups. While FGF21 infusion did not cause a significant change in food consumption, it caused a reduction in the body weight of rats (p < 0.05). Our findings indicate that FGF21 may have an effect on energy metabolism via the HPT axis.

The effects of intracerebroventricular infusion of irisin on feeding behaviour in rats.

Irisin, a novel exercise-induced myokine, has attracted attention with its effects on energy metabolism. This study was conducted to determine the possible effects of irisin on nutritional behaviour. In this study, 40 male Wistar Albino rats were separated into 4 groups (n=10 for each group). Osmotic mini-pumps were connected to metal cannulas implanted to lateral ventricle; and artificial cerebrospinal fluid (vehicle), and 10 and 100nM of irisin was infused for 7days. The daily food and water consumptions and body weights of rats were followed up. After the infusion, the animals were killed, and the hypothalamus and blood samples were collected. NPY, POMC, and UCP2 mRNA levels in the hypothalamus were examined by RT-PCR. In serum, leptin and ghrelin levels as well as the levels of metabolic parameters were measured by using ELISA. It was determined that irisin administration increased the daily food consumption (p<0.05), without causing significant changes in water consumption and body weight. Irisin also caused increases in ghrelin level in circulation and NPY and UCP2 mRNA levels in the hypothalamus, whereas it decreased the leptin level in circulation and POMC mRNA levels in the hypothalamus (p<0.05). Otherwise, irisin caused decrease in LDL, triglycerides and cholesterol levels, while increasing HDL and glucose levels (p<0.05). Results indicates that long-term irisin treatment increases food intake without increasing body weight associated with increased ghrelin, NPY and UCP2 mRNAs, and decreased leptin and POMC mRNA in the hypothalamus.

Kisspeptin-10 elicits triphasic cytosolic calcium responses in immortalized GT1-7 GnRH neurones.

Kisspeptins, which are alternatively called as metastin since they were originally identified as products of metastasis suppressor gene KiSS-1, are the natural ligands for the G protein-coupled receptor 54 (GPR54). Kisspeptins are the most potent activators of hypothalamic-pituitary-gonadal (HPG) axis reported to date. The pulsatile pattern of GnRH release, which results in the intermittent release of gonadotropic hormones from the pituitary, has a critical importance for reproductive function but the factors responsible from this release pattern are not known. Therefore, the pattern of kisspeptin-induced intracellular signaling and the role of PKC in the intracellular signaling cascade were investigated by fluorescence calcium imaging using the immortalized GnRH-secreting GT1-7 hypothalamic neurons. Kisspeptin-10 caused a triphasic change characterized by an initial small increase followed by a significant decrease and increase in intracellular free calcium concentrations ([Ca(2+)](i)). The changes in [Ca(2+)](i) were significantly attenuated by pre-treatment with protein kinase C inhibitor. The compatibility of appeared mirrored-patterns of kisspeptin-10-induced changes in [Ca(2+)](i) concentrations in these neurons and GnRH secretion confirm the importance of intracellular calcium flux downstream from GPR54 through PKC signaling pathway.

Melatonin inhibits testosterone secretion by acting at hypothalamo-pituitary-gonadal axis in the rat.

OBJECTIVES: We have investigated the changes in serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone levels together with testicular histology in both pinealectomized (PNX) and intact rats. MATERIAL and METHODS: Twenty-one animals were PNX and allowed to recover for two months. Group I was assigned as PNX, group II PNX+melatonin and group III PNX+Human Chorionic Gonadotropin (HCG). Rats in group IV were sham PNX (S-PNX). An intact group of animals was s.c. injected with melatonin (0.5 mg/kg/day), another group with a combination of melatonin+HCG (5000 IU/kg/day) for seven days. Controls received saline alone (1 ml/kg). At the end, all animals were decapitated and blood samples obtained. Serum LH and FSH levels were determined by Radioimmunoassay, testosterone values by Chemiluminescent Enzyme Immunassay. Testicular tissue was collected and processed for light microscopy. RESULTS: Serum LH levels were increased following PNX, but no such increases were seen in testosterone. In the PNX+melatonin group, serum LH and testosterone values were found to be similar to those of S-PNX group. HCG supplementation to PNX rats resulted in significant decreases in LH (p<0.005), but increased testosterone levels (p<0.001). Melatonin administration to intact animals significantly decreased both LH and testosterone levels (p<0.01). Co-administration of HCG+melatonin resulted in significant decreases in LH (p<0.001) and increases in testosterone levels (p<0.01). Serum FSH values did not show significant changes among groups. Only HCG administration significantly reduced FSH levels (p<0.01). CONCLUSIONS: Our results suggest that melatonin inhibits testosterone secretion by acting at hypothalamo-pituitary axis. There is a functional relationship and feedback regulation between the pineal gland and the testes.