title: Subcutaneous administration of Kiss1 pentadecapeptide accelerates spermatogenesis in prepubertal male chub mackerel (Scomber japonicus).
abstract: Kisspeptins, encoded by kiss genes, have emerged as critical regulator of reproductive function in vertebrates. Our previous studies demonstrated that the chub mackerel (Scomber japonicus) brain expresses kiss1 and kiss2 and peripheral administration of synthetic Kiss1 pentadecapeptide (Kiss1-15) but not Kiss2 dodecapeptide (Kiss2-12) induces spermiation in sexually immature adult chub mackerel. In the present study, we evaluated the potency of Kiss1-15, Kiss2-12, and GnRH analogue (GnRHa) to induce pubertal onset in prepubertal chub mackerel. Peptides were administered through subcutaneous injection for three times (bi-weekly) over 6weeks. Interestingly, gonadosomatic index (GSI) of Kiss1-15 treated fish increased significantly in comparison to other treatments. Histologically, 66.7% of Kiss1-15 treated fish exhibited presence of spermatozoa (SPZ) in the testes with only 28.6% of GnRHa treated fish. However, Kiss2-12 treated fish showed only spermatocytes (SC) as the advanced germ cells in the testes. In contrast, only spermatogonia (SPG) were observed in the testes of control fish. Changes in the number of testicular germ cells among treatments revealed a significantly higher number of SC, spermatids and SPZ in the Kiss1-15 treated fish. Gene expression analyses revealed no significant changes in gnrh1 in the telencephalon-preoptic region of the brain, including fshβ and lhβ in the pituitary of experimental fish. However, GnRHa treated fish showed significantly higher lhβ expression. Levels of sex steroids, 11-ketotestosterone and estradiol-17β were significantly higher in Kiss1-15 treated fish. These results indicate application of Kiss1-15 peptides for accelerating pubertal onset in chub mackerel.
authors.affiliation: Laboratory of Marine Biology, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Sethu
authors.initials: S
authors.lastname: Selvaraj
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ohga
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Nyuji
authors.forename: Hajime
authors.initials: H
authors.lastname: Kitano
authors.forename: Naoki
authors.initials: N
authors.lastname: Nagano
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Michiya
authors.initials: M
authors.lastname: Matsuyama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004958:Estradiol / Q000097:blood; D029941:Fish Proteins / Q000008:administration & dosage* / Q000737:chemistry; D007279:Injections, Subcutaneous; D059648:Kisspeptins / Q000008:administration & dosage* / Q000737:chemistry; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000737:chemistry; D010473:Perciformes / Q000502:physiology*; D013091:Spermatogenesis / Q000187:drug effects*; D013737:Testis / Q000166:cytology / Q000187:drug effects; D013739:Testosterone / Q000097:blood
chemical_list: D029941:Fish Proteins; D059648:Kisspeptins; D010446:Peptide Fragments; D013739:Testosterone; D004958:Estradiol
keywords: 11-KT; 11-ketotestosterone; 17,20β-P; 17,20β-dihydroxy-4-pregnen-3-one; E2; FSH; GSI; GnRH; GnRH analogue; GnRHa; GtHs; Kiss-10; Kiss1-15; Kiss2-12; Kisspeptins; LH; Spermatogenesis; T; estradiol-17β; follicle stimulating hormone; gonadosomatic index; gonadotropin-releasing hormone; gonadotropins; kiss1 pentadecapeptide; kiss2 dodecapeptide; kisspeptin decapeptide; luteinizing hormone; testosterone