Injections Of Luteinizing Hormone-releasing Hormone Analogue Research Articles

Broodstock Rearing and Controlled Reproduction of Reeves Shad Tenualosa reevesii

AbstractReeves shad Tenualosa reevesii is one of China's best known anadromous fish, but is presently on the verge of extinction. There is an urgent need for conservation of this species through artificial reproduction and culture. In this study, shad broodstock were held in captivity then were induced to spawn with serial injections of luteinizing hormone‐releasing hormone analogue (LHRHa) following GtH priming by implantations of 17‐methytestosterone (T) combined with environmental manipulations. Induced maturation of 4, 5, and 6‐year‐old females reached 83.3%, 87.5%, and 100%, respectively, while fish in control treatments remained immature. During the gonadal development priming period, mean serum 17‐estradiol levels in the T treatment were significantly higher than the LHRHa treatment and control fish. Gonadal development of females was suppressed when their mesenteric fat index was below 1.5% by April. The effective accumulating temperatures for female and male maturation were 3,995 ± 31.4 C/d and 2,278 ± 8.9 C/d, respectively. Two injections of LHRHa in combination with domperidone (DOM) and environmental regulations were effective in inducing ovulation. About 800,000 fertilized ova were obtained (fertilization 75%) in 1995, and 5,000 fry were hatched in 1996. These results are an important step to develop shad culture and save this endangered species.

Effects of controlled delivery and acute injections of LHRHa on bullseye puffer fish ( Sphoeroides annulatus) spawning

Mature bullseye puffer ( Sphoeroides annulatus) fish were caught and taken into captivity. Fish with a mean oocyte diameter greater than 0.45 mm were divided equally into three experimental groups ( n=11) that were treated with a saline injection (control), multiple injections of luteinizing hormone-releasing hormone analogue (LHRHa) (day 0—20 μg kg −1, day 2—40 μg kg −1, day 4—80 μg kg −1, day 6—160 μg kg −1) and a single administration of slow-release ethylene vinyl acetate (EVAc) co-polymer implants containing the identical LHRHa (day 0—75 μg per fish <800 g or 150 μg per fish >800 g). A total of 82% of the fish spawned in each of the two LHRHa groups (injection and implant) compared to just 18% in the control group. The majority of the fish treated with LHRHa, eight in the injection group and nine in the implant group, spawned during the first week after administration. There were no significant differences in mean egg size (group means 0.64–0.71 mm) and percentage fertilization (group means 90.2–97.3%) among the LHRHa-treated groups and when compared with the control fish that received saline injection and fish that ovulated naturally without any treatment. The successful spawning using LHRHa-based spawning protocols is an important step in the development of the culture of the bullseye puffer.

The efficacy of exogenous hormones in stimulating changes in plasma steroids and ovulation in wild black bream Acanthopagrus butcheri is improved by treatment at capture

Sexually mature female black bream were captured by rod and line and injected with saline, human chorionic gonadotropin (hCG) or luteinizing hormone releasing hormone analogue (LHRHa) at capture, or 24 h post capture (saline and LHRHa treatments only). All fish were bled and checked for ovulation for 5 days post injection. Plasma levels of oestradiol (E 2), testosterone (T), 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) and cortisol were determined by radioimmunoassay. Saline-injected fish ovulated only on day 1, whereas treatment with LHRHa or hCG resulted in fish ovulating throughout the experiment. Treatment with LHRHa at capture resulted in a better ovulatory response than treatment with hCG at capture or LHRHa 24 h post capture. Plasma E 2 levels in saline-injected fish were high at capture and had significantly dropped 1 day after capture. Injection with hCG or LHRHa at capture resulted in plasma E 2 levels remaining significantly elevated for 2 days post injection. Injection of LHRHa 24 h post capture failed to significantly elevate plasma E 2 levels over controls. Plasma T levels were similar to E 2 profiles. Plasma levels of 17,20βP were not significantly different between any treatments, but showed a tendency to increase after capture. Plasma cortisol levels showed no treatment effects and were initially low at capture before becoming elevated between days 1 and 2 post capture. These results show that capture and handling stress reduce the responsiveness of fish to exogenous hormone treatment and that best results are obtained if hormonal treatment is administered at the time of capture.

Maintenance at elevated temperature delays the steroidogenic and ovulatory responsiveness of rainbow trout Oncorhynchus mykiss to luteinizing hormone releasing hormone analogue

Vitellogenic rainbow trout were held at 12 or 18°C for 83 days; then injected with either saline or luteinizing hormone releasing hormone analogue (LHRHA). Repeat blood samples were taken over the 96 h following injection, and fish were monitored for ovulation for up to 44 days post-treatment. Most fish held at 12°C ovulated in response to LHRHA within 8 days of injection, whereas controls began to ovulate 19 days after injection and all had undergone ovulation by day 44. In contrast, no control or LHRHA-injected fish held at 18°C underwent ovulation for 23 days after injection. Fish held at 18°C were reinjected with saline or LHRHA 25 days after first treatment, and were now responsive to LHRHA, with six out of eight fish ovulating within 11 days of injection. Spontaneous ovulation also occurred in about half of control fish at 18°C over the 20 days following the second injection. Eggs from all ovulations were incubated at the same holding temperature as the adults. Eggs held at 12°C showed high survival to neural streak (>90%) and eyed stages (>80%), whereas incubation at 18°C resulted in low survival to equivalent stages (<60 and <50%, respectively). LHRHA-injected fish at 12°C showed a significant fall in plasma 17β-oestradiol (E 2) at 72 and 96 h post-injection (pi), a transient increase in plasma testosterone (T) at 24 h pi, and a marked elevation in 17, 20β-dihydroxy-4-pregnen-3-one (17,20βP) at 48, 72 and 96 h pi relative to controls. At 18°C (first injection) LHRHA-injected fish had elevated plasma T at 48 h pi, but no changes in plasma levels of E 2 or 17,20βP. In contrast, the plasma steroid profile of fish at 18°C after the second injection of LHRHA was very similar to that shown by fish at 12°C at first injection. Ovarian follicles from fish held at 12°C were unresponsive to in vitro treatment with human chorionic gonadotropin (hCG), whereas follicles from fish held at 18°C produced increased amounts of E 2 in response to hCG. This was consistent with the low aromatase activity seen in vivo in fish held at 12°C. The results show that maintenance at elevated temperature retards steroidogenic responsiveness to LHRHA, either by delaying pituitary responsiveness to LHRHA, or the shift in ovarian steroid secretion from E 2 to 17,20βP.

Bioactivity of stored luteinizing hormone-releasing hormone analogue (LHRHa) in sea bass, Lates calcarifer Bloch

The spawning induction activity of dissolved and pelleted (D-Ala6, Pro9 N ethylamide) luteinizing hormone-releasing hormone analogue (LHRHa) stored for various periods was assessed in mature female sea bass. The spawning response of mature fish was reduced significantly after injection of dissolved LHRHa (20 μg kg−1) stored for more than 90 days in a refrigerator (4–10°C) or for more than 30 days at room temperature (28–30°C). Similar to fish administered fresh preparations of LHRHa, fish spawned successfully after injection of a solution of LHRHa previously frozen, subjected to alternate freezing and thawing, exposed to sunlight or implanted pelleted LHRHa (50 ng kg−1) stored at room temperature for 30–120 days. Loss of hormone bioactivity after prolonged storage may have been due to bacterial growth in solubilized preparations. Injection or implantation of stored LHRHa did not influence egg production among treated sea bass. These results demonstrated the relatively prolonged shelf life of stored LHRHa.

Sustained production of milt in rabbitfish, Siganus guttatus Bloch, by weekly injection of luteinizing hormone-releasing hormone analogue (LHRHa)

Mature male rabbitfish ( Siganus guttatus Bloch) received weekly injections of 200 μg of luteinizing hormone-releasing hormone analogue (D-Ala 6, Pro 9-LHRH-ethylamide) per kg body weight for 5 consecutive weeks. Mean spermatocrit, or packed sperm volume (27–51%), and mean sperm density (3.2–9.6×10 6 spermatozoa per kg body weight) decreased significantly 24 h after each injection. The amount of expressible milt (mean: 5.8–11.7 ml per kg) in response to weekly injections of LHRHa increased significantly relative to saline-injected fish (1.0–2.9 ml per kg), but only during the initial 4 weeks of regular hormone treatment. Three weekly injections of LHRHa likewise augmented mean sperm production (29.2–112.5×10 9 spermatozoa per kg) in rabbitfish. However, no significant enhancement in sperm production by LHRHa-injected fish was observed over the last 2 weeks of hormone injection. These results demonstrate that weekly injection of LHRHa can sustain milt production in mature rabbitfish, although their capacity to produce spermatozoa is limited to only 3 consecutive weeks of regular hormone treatment.

Induction of maturation and ovulation by pimozide-LHRH analogue treatment and resulting high quality egg production in the Asian catfish, Clarias batrachus (L.)

In Clarias batrachus (250–310 g), collected from nature in the early spawning season, simultaneous injections of pimozide (a dopamine antagonist) and the luteinizing hormone-releasing hormone analogue (LHRHa), des-Gly 10 [D-Ala 6]-LHRH ethylamide, caused a high rate of ovulation (85.7%), while injections of either pimozide or LHRHa alone or the vehicle medium did not. The ovulated fish produced an average of 21.15±2.6 g eggs with a very high hatching rate (91.88±1.51%) and a high yield of normal fry (85.5±3.1%). The results suggest that the combination can be used as a simple and efficient method for inducing ovulation in the catfish.

Induction of ovulation in female mud skipper (Boleophthalmus pectinirest ris) by HCG, analogue of LHRH and pimozide

The effects of two intraperitoneal injections of human chorionic gonadotropin (HCG) or [D-ALA6, pro9-N-ethylamide]-luteinizing hormone releasing hormone analogue (LHRH-A), respectively, and the combined effect of LHRH-A with pimozide (PIM), a dopamine antagonist, on ovulation in female mud skipper were investigated. A high rate of ovulation (83.3%) was observed after injection with HCG(30 I. U./g). Injection of LHRH-A at a total dosage of 2 μg/g was 100% effective in inducing ovulation. No ovulations occurred in the group receiving a low dosage of LHRH-A (0.02 μg/g). Injection of LHRH-A (0.2 μg/g) with PIM (10 or 20 μg/g) induced greater ovulatory response than injection with LHRH-A (0.2 μg/g) alone. PIM at total dosages of 0.2 μg/g or 2 μg/g did not enhance the potency of LHRH-A to stimulate ovulation.

Luteinizing hormone-releasing hormone analogue induces precocious ovulation in adult coho salmon (Oncorhynchus kisutch)

Abstract Adult female coho salmon ( Oncorhynchus kisutch ) were injected intraperitoneally with the luteinizing hormone-releasing hormone analogue (LH-RHa) des-Gly 10 [D-Ala 6 ]-LH-RH-ethylamide at various dosages to induce precocious final maturation. The mean number of days to ovulation in all groups receiving LH-RHa was significantly lower than that of saline-injected controls. Within 13 days of the initial injection, at least 84% of the fish receiving two injections spaced 3 days apart of LH-RHa at various dosages had ovulated, at least 67% of the fish receiving single injections of LH-RHa at two dosages had ovulated, whereas less than 50% of the controls had ovulated. In all the groups receiving LH-RHa, the percent fertilization of the eggs was less than that of the control group.