Abstract
Catla (Catla catla) is one of the most important species of cyprinids in terms of economic and nutritional value that was considered as aquaculture candidate in Khozaestan province (Iran). In this study, 40 female and male Catla broodstocks (imported from India), were studied during year (summer 2011 to spring 2012). Seasonally, blood sampling was collected with heparinated syringe followed by catching and anesthesia. Levels of steroid hormones (testosterone, 17β-estradiol and progesterone) were measured by RIA. Results showed significant differences in all sex steroids during seasonal sampling (P<0.05). High plasma testosterone levels were measured in both sexes (female: 0.13 ± 0.03 ng/ml and male: 0.16 ± 0.04 ng/ml) in the course of the sexual maturation at the end of winter. Highest female plasma levels of 17 β-estradiol (128.50 ± 26.60 ng/ml) was measured in fall. Progesterone also significantly increased at winter (1.32 ± 0.22 ng/ml) in female broodstocks (P<0.05). All broodstocks were ripe and ready to breeding in winter. Water temperature was higth (29.88 ± 1.42) in summer which declined to (14.63 ± 0.47) in winter. According to the results, climatic conditions (Temperature) had a great impact on broodstocks Gonad development via involving of hormones in Khuzestan.
Highlights
Reproduction is an important factor ensuring the continuation of a species by recruitment of the generation; and Successful reproduction in seasonally breeding vertebrates depends on temporal variations in gametogenesis, reproductive behaviors, and steroid hormone production [1]
Seasonal changes in the concentrations of circulating sex hormones and their importance for reproduction has been reported for several species of teleosts [13]
Annual rhythm of hormones closely related to factors such as temperature, environment, species of fish, length of day and gonadal sex steroids [2]
Summary
Reproduction is an important factor ensuring the continuation of a species by recruitment of the generation; and Successful reproduction in seasonally breeding vertebrates depends on temporal variations in gametogenesis, reproductive behaviors, and steroid hormone production [1]. Reproduction in teleosts, as in other vertebrates, is under hormonal regulation by the brain-pituitary-gonadal axis (BPG axis). The main factors involved in the regulation of reproductive function are pituitary gonadotropins and gonadal steroids. Hormones are regulators which affect cells metamorphism. Hormones are not beginner of reaction and many physiological actions undergo without them. Sex steroids have long been recognized as key hormones regulating sexual differentiation, physiological aspects of reproduction and the development of primary and secondary sexual characteristics [2]
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