Abstract. The aims of the present study were to clarify the effect of kisspeptin-10 (Kp10) on the secretion of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and growth hormone (GH) in prepubertal male and female cattle. The experiments were performed from May to June using five male (4-6 months old) and five female (5-6 months old) Japanese Black calves. A single intravenous (iv) injection of Kp10 (5 μg/kg body weight (b.w.): 3.85 nmol/ kg b.w.)significantly stimulated the release of LH and FSH in male and female calves (P<0.05). A single intramuscular injection of Kp10 (5 μg/kg b.w.) also significantly stimulated the release of LH and FSH in male calves (P<0.05), though the response was smaller than that to the iv injection. The injection of Kp10 did not alter the basal plasma concentration of GH in male or female calves. The area under the curve (AUC) of both LH and FSH for a 120-min period after the iv injection of Kp10 was significantly greater in the males than females (P<0.05). These results show that Kp10 can stimulate the release of LH and FSH in calves of both sexes and that the response to the peptide is greater in males at this age. They also show that Kp10 has no effect on the release of GH in male and female calves and that the LH-and FSHreleasing effect of Kp10 is greater after an iv injection than after an im injection in calves. Key words: Cattle, Follicle-stimulating hormone (FSH), Growth hormone (GH), Kisspeptin-10, Luteinizing hormone (LH) (J. Reprod. Dev. 55: 650-654, 2009) he pituitary's release of gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), is essential to normal gonadal development and function [1], such as ovulation in females and spermatogenesis in males [2]. The brain-pituitarygonadal axis is operated by the decapeptide gonadotropin-releasing hormone (GnRH) in the mammalian brain. However, recently, the KiSS-1/GPR54 system in the hypothalamus was implicated in the regulation of this axis [3][4][5].Kisspeptin is the product of the KiSS-1 gene, which encodes a 145-amino acid peptide that is further processed to generate biologically active peptides of various lengths (10-54 amino acids) termed kisspeptins [5,6]. Kisspeptin neurons are found in the hypothalamus [7][8][9], and kisspeptins strongly stimulate the secretion of gonadotropin through a G protein-coupled receptor known as GPR54 [3][4][5]. The actions of these peptides are thought to involve mainly stimulating GnRH's neuronal activity through GPR54 [3][4][5].An administration of kisspeptin, either centrally or peripherally, has been shown to elicit the release of gonadotropins in ruminants [10][11][12][13][14][15] as well as in rats [16,17], pigs [18], monkeys [19] and humans [20,21]. However, in cattle, only two in vivo studies have been conducted [13,14], and the precise effects of kisspeptin on the secretion of pituitary hormones under physiological conditions are unknown.Puberty as a successful reproductive event is closely related to interactions between the gonadotropic axis ...

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Chromium (Cr) is a toxic heavy metal that contaminates soil and water resources after its discharge from different industries. A pot experiment was conducted to determine the effects of single and/or combined application of sodium nitroprusside (SNP) (250 μM) and sodium hydrogen sulfide (NaHS) (1 mM) on growth, photosynthetic pigments, gas exchange characteristics, oxidative stress biomarkers, antioxidant machinery (enzymatic and non-enzymatic antioxidants), ion uptake, organic acid exudation, and Cr uptake of spinach (Spinacia oleracea L.) exposed to severe Cr stress [Cr: 0 (no Cr), 150, and 300 μM]. Our results depicted that Cr addition to the soil significantly (P &lt; 0.05) decreased plant growth and biomass, gas exchange attributes, and mineral uptake by S. oleracea when compared to the plants grown without the addition of Cr. However, Cr toxicity boosted the production of reactive oxygen species (ROS) by increasing the content of malondialdehyde (MDA), which is the indication of oxidative stress in S. oleracea, and was also manifested by hydrogen peroxide (H2O2) content and electrolyte leakage to the membrane-bound organelles. The results showed that the activities of various antioxidative enzymes, such as superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and the content of non-enzymatic antioxidants, such as phenolic, flavonoid, ascorbic acid, and anthocyanin, initially increased with an increase in the Cr concentration in the soil. The results also revealed that the levels of soluble sugar, reducing sugar, and non-reducing sugar were decreased in plants grown under elevating Cr levels, but the accumulation of the metal in the roots and shoots of S. oleracea, was found to be increased, and the values of bioaccumulation factor were &lt;1 in all the Cr treatments. The negative impacts of Cr injury were reduced by the application of SNP and NaHS (individually or combined), which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes, and mineral uptake, as well as diminished the exudation of organic acids and oxidative stress indicators in roots of S. oleracea by decreasing Cr toxicity. Here, we conclude that the application of SNP and NaHS under the exposure to Cr stress significantly improved plant growth and biomass, photosynthetic pigments, and gas exchange characteristics; regulated antioxidant defense system and essential nutrient uptake; and balanced organic acid exudation pattern in S. oleracea.