Seasonal changes in expression of LH-beta and FSH-beta in male and female three-spined stickleback, Gasterosteus aculeatus.
In teleost fishes, like in other vertebrates, the gonadal development is stimulated by two gonadotropic hormones; luteinizing hormone (LH) and follicle-stimulating hormone (FSH). To achieve a better understanding of the role of gonadotropins in teleost reproduction; expression of LH-beta and FSH-beta mRNA and the status of gonads and secondary sexual characters were analyzed over the annual cycle in male and female three-spined sticklebacks, a species in which the development of male secondary sexual characters and spermatogenesis are separated in time. The kidney in the male stickleback hypertrophies during the breeding season and produces a glue used when building nests. Kidney weights, as well as levels of 11-ketotestosterone (11KT), reached a peak in May. Both testosterone (T) levels and the gonadosomatic index (GSI, gonad weight/body weight x 100) in females started to increase in April, and peaked in May as well. Later in summer, after the breeding season, these features declined. In females, LH-beta expression followed the GSI and T levels closely, levels were low during winter and early spring, increased to a peak in late May and declined to low levels again in July. FSH-beta expression peaked earlier, in January and declined slowly over spring. In males, LH-beta expression peaked in May. During June-September, when spermatogenesis was active, LH-beta levels were very low. FSH-beta expression peaked in January, earlier than LH-beta expression did, and reached the lowest levels in July. Thus, when spermatogenesis started at the end of summer, the expression of both GTH-beta mRNAs, and circulating 11KT, displayed their lowest levels.
Hellqvist
Anna
A
Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden. ahellqvist@nl.rogers.com
Schmitz
Monika
M
Mayer
Ian
I
Borg
Bertil
B
D000818:Animals; D001835:Body Weight / Q000502:physiology; D005260:Female; D029941:Fish Proteins / Q000235:genetics; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D007668:Kidney / Q000033:anatomy & histology; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics*; D008297:Male; D009929:Organ Size / Q000502:physiology; D010053:Ovary / Q000033:anatomy & histology; D012621:Seasons; D023701:Smegmamorpha / Q000235:genetics* / Q000502:physiology; D013091:Spermatogenesis / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood
D029941:Fish Proteins; D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D013739:Testosterone; C003600:11-ketotestosterone