Fundulus grandis Response to Exogenous LH Injection.

Piscine responsiveness to exogenous mammalian gonadotropin injection was assessed in Fundulus grandis, the Gulf killifish. Responsiveness was measured through the reproductive parameters of plasma sex steriod levels (estrogen for the female and testosterone for the male animals) as well as gonadalsomatic indexes, GSI. Females were also evaluated on the microscopic and macroscopic appearance of the ovary. Injections of ovine luteinizing hormone (o-LH) were made at different times of the day (early, midday, and late) as well as during times of differing reproductive condition (different times of the year). Additionally, a dose response curve to the o-LH was determined on both sexes. The females could be grouped into a "developing" versus "mature" category, based on gonadal inspection. In both developing and mature fish, there was no effect on GSI with LH treatment. Estrogen levels increased significantly in developing fish at the early and midday injection times; however, mature fish failed to respond to the LH at any injection time. Additionally, experiments where plasma testosterone levels in the female were measured, a significant response was not noted. Finally, the dose response curve of o-LH revealed the largest increase in plasma estrogen levels occurred with the 2 ug/gm BW dose, but this was not statistically different from the other doses. In the male, LH treatment had no effect on the GSI; however, in all but 4 groups, plasma testosterone levels were greatly enhanced. Testosterone levels peaked at 2 and 8 ug/gm BW doses, whereas 11-ketotestosterone showed a consistent response to the increasing dosage levels. These studies indicate a sensitivity of the Fundulus to the exogenous hormone treatment that is, at least for the female, contingent upon the time of day of injection as well as gonadal stage of development. This would suggest a possible rhythm of endogenous gonadotropin in the Fundulus grandis, where low levels of the endogenous gonadotropin would allow responses to occur with LH treatment.

Level thesis:degree_level

Thesis

Year

1984

Author dc:creator

• Reddington, Mary Claire

• Fundulus grandis
• Piscine responsiveness
• Exogenous mammalian
• Gonadotropin injection
• Ovine luteinizing hormone

Repository record dc:identifier

https://digitalcommons.library.uab.edu/etd-collection/7153

OAI identifier oai:identifier

oai:digitalcommons.library.uab.edu:etd-collection-8145