Kisspeptin 10 (rat)

Background:Kisspeptin peptides mediate their actions through the GnRH loop system. How kisspeptins affect prostate gland in prepubertal male mammals remains elusive.Methods:To address this kisspeptin was administered as subchronic (12 days) twice daily i.p. dose at three different dosage regimens: 10 pg, 1 ng and 1 µg, to prepubertal male Sprague-Dawley rats (PND 35). Control rats were maintained in parallel. At the end of the experiment prostate gland was dissected out and processed for light and electron microscopy. DNA damage was also estimated by DNA ladder assay and DNA fragmentation assay.Results:Prostate weights decreased significantly (P < 0.05) at 1 µg treatment dose of kisspeptin. The epithelial height of secretory acini of prostate decreased at 10 pg (P < 0.05), 1 ng, and 1 µg doses (P < 0.001). Histomorphology and ultrastructure demonstrated, decrease in epithelial cell height, epithelial folding and dilatation of the organelles with kisspeptin treatment. Percent DNA damage to the prostatic tissue was 20.74 ± 2.18, 43.60 ± 2.39, and 58.18 ± 2.59 at 10 pg, 1 ng and 1 µg doses, respectively.Conclusion:The study reveals that continuous administration of kisspeptin does not lead to an early maturation but instead severe degeneration of prepubertal prostate gland. Wiley Periodicals, Inc.

Kisspeptin is a hypothalamic peptide hormone that plays a pivotal role in pubertal onset and reproductive function. Previous studies have examined hypothalamic kisspeptin mRNA expression, either through in situ hybridisation or real-time RT-PCR, as a means quantifying kisspeptin gene expression. However, mRNA expression levels are not always reflected in levels of the translated protein. Kisspeptin-immunoreactivity (IR) has been extensively examined using immunohistochemistry, enabling detection and localisation of kisspeptin perikaya in the arcuate nucleus (ARC) and anteroventral periventricular nucleus (AVPV). However, quantification of kisspeptin-IR remains challenging. We developed a specific rodent radioimmunoassay assay (RIA) capable of detecting and quantifying kisspeptin-IR in rodent tissues. The RIA uses kisspeptin-10 as a standard and radioactive tracer, combined with a commercially available antibody raised to the kisspeptin-10 fragment. Adult female wistar rat brain samples were sectioned at 300 µm and the ARC and AVPV punch micro-dissected. Brain punches were homogenised in extraction buffer and assayed with rodent kisspeptin-RIA. In accord with the pattern of kisspeptin mRNA expression, kisspeptin-IR was detected in both the ARC (47.1±6.2 fmol/punch, mean±SEM n = 15) and AVPV (7.6±1.3 fmol/punch, mean±SEM n = 15). Kisspeptin-IR was also detectable in rat placenta (1.26±0.15 fmol/mg). Reverse phase high pressure liquid chromatography analysis showed that hypothalamic kisspeptin-IR had the same elution profile as a synthetic rodent kisspeptin standard. A specific rodent kisspeptin-RIA will allow accurate quantification of kisspeptin peptide levels within specific tissues in rodent experimental models.

Kisspeptin is the natural ligand of the G protein-coupled receptor -54 and plays a major role in gonadotropin-releasing hormone secretion in the hypothalamus. Kisspeptin-10 is an endogenous derivative of kisspeptin and has 10 -amino acids. Previous studies have demonstrated that central administration of kisspeptin-10 stimulates the secretion of arginine vasopressin (AVP) in male rats. We examined the effects of kisspeptin-10 on- excitatory synaptic inputs to magnocellular neurosecretory cells (MNCs) including AVP neurons in the supraoptic nucleus (SON) by obtaining in vitro whole-cell patch-clamp recordings from slice preparations of the rat brain. The application of kisspeptin-10 (100 nM-1 μM) significantly increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in a dose-related manner without affecting the amplitude. The kisspeptin-10-induced potentiation of the mEPSCs was significantly attenuated by previous exposure to the kisspeptin receptor antagonist kisspeptin-234 (100 nM) and to the protein kinase C inhibitor bisindolylmaleimide I (20 nM). These results suggest that kisspeptin-10 participates in the regulation of synaptic inputs to the MNCs in the SON by interacting with the kisspeptin receptor.