Category Archives: Testosterone

Effects of Long-Term Testosterone: DISCUSSION(8)

However, GtH I displayed a 100-fold greater ability to induce vitellogenin uptake by vitellogenic rainbow trout oocytes. Therefore, it can also be suggested that, because of an insufficient increase in plasma GtH I levels, ovarian development—and specifically vitellogenesis—werenotsuffieiently stimulated. Unfortunately, … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(7)

The present study shows that the T-containing treatments not only increased pituitary GtH II levels, but also stimulated ovarian development slightly as was evident by the increase in mean GSI and the presence of SG oocytes. Additionally, the T+ high … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(6)

Therefore, it is not likely that a longer treatment would have resulted in a more significant stimulation of ovarian development. In vitro incubation of ovarian fragments showed that fish from the T+ high GnRHa group had a significantly increased ability … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(5)

Increased plasma GtH II levels were observed only in fish that were treated with a combination of T and high doses of GnRHa (experiment 2). However, fish from all T-treated groups had a significantly higher mean GSI. Since fish from … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(4)

Although the inhibitory effects of pimozide on GtH II release may suggest a stimulatory role of dopamine on GtH II secretion, this finding is not supported by other studies. In fact, in mature fish, the addition of a dopamine antagonist … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(3)

Fish from all groups, including the control, were able to release GtH II in response to an acute GnRHa challenge (Fig. 4B). This observation indicates that the GtH II in the pituitary was in a releasable form. Fish from the … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(2)

Regardless of the increase in pituitary GtH II levels, the T (experiment 1), T+P (experiment 2), and combined T+ GnRHa (experiments 1 and 2) treatments were unsuccessful in increasing plasma GtH II levels. However, when fish were treated with a … Continue reading

Effects of Long-Term Testosterone: DISCUSSION(1)

Previous studies have demonstrated that gonadal steroids stimulate GtH synthesis in immature fish by either affecting the pituitary directly, or indirectly by stimulating the GnRH levels in the brain. The present study shows that in juvenile female striped bass also, … Continue reading

Effects of Long-Term Testosterone: RESULTS(6)

The reason for these differences is unclear. It is possible that the different origin of the fish (genetic factors) and differences in water temperature contributed to the discrepancies. Nevertheless, GtH II response to the hormonal treatments was similar in both experiments, … Continue reading

Effects of Long-Term Testosterone: RESULTS(5)

These secondary growth (SG) oocytes were not very numerous and were scattered in tissue containing predominately PG and ESG oocytes. Females from the control and GnRHa+P groups had only PG- or ESG-stage oocytes (Fig. 3A). The number of fish with … Continue reading