Introduction: Several hormonal types, including pituitary hormones of common carp, were used for induced spawning in marine fish.
Aim of the work: The aim of this study is to evaluate the hormonal content of the pituitary gland for different types of carp fish, used to stimulate spawning in marine fish, by using immunohistochemical technique.
Material and methods: In this study, the pituitary glands of mature males and females in three types of carp; common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix), were selected for evaluation as a source of hormones. In this regard, these pituitaries were immunohistochemically stained using corticotropin-releasing factor (CRF), adrenocorticotropin hormone (ACTH), gonadotropin hormones IIβ (GTH IIβ) and somatolactin hormone (SL).
Results: The results showed that the pituitary gland of silver carp had higher immunoreactivity; the number, size, and immunostaining of GTH IIβ and SL hormones than those of common carp and grass carp. The integrated optical density (IOD) of immunoreactivity of the two hormones in silver carp was significantly higher than those of common carp and grass carp. However, the immunoreactivity of stress-response hormones; CRF and ACTH in silver carp was significantly lower than those of common carp and grass carp; since lower number and size of ACTH-immunoreactive cells were obtained. Furthermore, significantly lower IOD of both CRF and ACTH were obtained in silver carp.
Conclusion: It could be concluded that the use of the pituitary gland of silver carp was effective to stimulate the spawning of mullets and less expensive.