Kisspeptin is the peptide product of the KISS-1 gene and endogenous agonist for the Kiss1 receptor. It is well known that kisspeptin acts centrally, and stimulates the secretion of gonadoliberin (GnRH). Further, Kisspeptin also interacts with other neuropeptides such as neurokinin B and dynorphin to regulate GnRH pulse generation and plays a key role in sexual behavior. This study aimed to evaluate the effect of kisspeptin on male rats' sexual motivation and its dependence on testosterone levels. In this study total of 50 copulation naive male Wistar rats were collected and divided into 5 groups (10 rats in each group), among these first group received only saline (control), the second group has been given 20μg buserelin acetate (GnRH analogue), the third group has been given intranasally kisspeptin-10 (3ng), the fourth has been received intraperitoneally kisspeptin-10 (30ng) and the fifth group has been given Yoquimbine 200 µg. Behavioral effects were registered in the open-field reward-proximity chamber with a female in the estrous phase of the cycle over the transparent perforated wall for 10 minutes in red light. Blood samples were collected from the tail vein after 30 minutes of the substance administration and in the collected blood samples, testosterone concentration was measured by the ELISA method. All animal groups were compared with each other by the ANOVA test and correspondent “post hoc” paired tests of Newman–Kruskall– Wallis test and Dunn’s test. Intranasal administration of buserelin acetate increased the concentration of testosterone but did not affect sexual motivation in rats. Further, intraperitoneal administration of Kisspeptin-10 enhances testosterone concentration and sexual motivation. While intranasal administration of kisspeptin-10 didn’t enhance testosterone level but increased sexual motivation. Results of this study showed some effects of kisspeptin along with the independent regulation of steroids.
The strong gettering of Cu atoms in single-crystal Si implanted with 3.5 MeV P ϩ ions is studied after thermal treatment and Cu contamination. Cu decorates the remaining implantation damage. Three separate Cu gettering layers are detected by secondary ion mass spectrometry: at the main projected ion range R P below R P (R P /2 effect͒ and beyond R P ͑trans-R P effect͒. The defects acting as gettering centers at R P /2 and R P are implantation induced excess vacancies and excess interstitials, respectively. Cu profiles fit very well with depth distributions of excess vacancies and excess interstitials determined by binary collision simulations for random and channeled ion incidence. The R P /2 effect for P ϩ implantation is found to be significantly reduced in comparison with Si ϩ implantation. It disappears completely for higher P ϩ ion fluences. The trans-R P gettering layer is formed by thermal treatment. The Cu accumulation in the trans-R P region increases with increasing temperature and/or with increasing annealing time. These results are in qualitative agreement with the assumption that interstitials carried by P diffusion are the origin of Cu gettering in the trans-R P region. The P diffusion may inject interstitials into the bulk and also into the R P /2 region thus decreasing the R P /2 effect.
The purpose of the review was to analyze the neurochemical and neurophysiological mechanisms of the ghrelin system and the role of ghrelin in body functions and behavior. The focus is on the participation of ghrelin in the mechanisms of reinforcement and the formation of addictive behavior. At the beginning of the review a history of the first works on the field of ghrelin and its receptor was described. Then, genetic control, molecular precursor of ghrelin, molecular forms of ghrelin and ghrelin receptor were represented. In particular, the distribution of the ghrelin receptor, ghrelin-producing cells in the brain and its participation in various physiological functions of the body were shown. The hypothalamic functions of ghrelin were discussed: energy balance, regulation of glucose metabolism, stimulation of eating behavior, regulation of hypophys-pituitary axis (HPA) system. The connection of ghrelin with the brain CRH system was demonstrated. In particular, activation of HPA was described as a possible mechanism through which ghrelin regulates a number of physiological processes. Extrahypothalamic action of ghrelin was shown on the basis of the mechanisms of reinforcement and addiction. On the basis of their own data and literary, it was concluded that action of alcohol and psychoactive drugs are reduced after the ghrelin receptors blockade. In particular, it has been demonstrated that alcoholization of mothers affects the activity of the ghrelin system during the prenatal and early postnatal periods of development in the offspring of rats. It was shown the participation of ghrelin in memory and learning. The further perspective of the study and practical application of ghrelin-based pharmacological agents was analyzed.
The review presents data on the expression of growth hormone secretagogue receptor 1a (GHS‐R1a) in the brain regions in model animals (zebrafish, rodents, primates), and in the human brain. Studies show widespread distribution of the receptor in the brain, which evidences the involvement of the receptor in many physiological processes. Using various organisms, data have been obtained regarding the participation of the GHS‐R1a in the regulation of the anti‐ and pro‐inflammatory response, proliferation, and apoptosis. It is known that the receptor plays an important role in eating behavior and is also involved in the pathogenetic mechanisms of drug addiction, obesity, and chronic alcohol consumption. Based on this, research is underway with the use of various therapeutic agents that can be used for the pharmacological correction of these conditions. This review also presents hypothetical pathways of intracellular signaling, in which GHS‐R1a may participate. A complete understanding of these mechanisms has not yet been reached. The ghrelin intracellular signaling seem to be specific to brain region and, probably, also depend on the metabolic or stress status of the organism.
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