Effects of exogenous hormone injections on milt consistency in newly caught, wild milkfish (original) (raw)
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Aquaculture, 2004
Spermiated male greenback flounder (Rhombosolea tapirina) were implanted with gonadotropin releasing hormone analog (GnRHa) pellets at different dosages to examine their effects on milt characteristics and plasma levels of testosterone (T), 11-ketotestosterone (11KT) and 17,20hdihydroxy-4-pregnen-3-one (17,20hP). Milt and blood samples were collected for up to 28 or 42 days post-implantation (p.i.) in two separate experiments using fish that were slightly or moderately spermiated, respectively. In both experiments, fish treated with GnRHa pellets showed a consistent and significant increase in milt volume relative to controls, and the increase of milt volume was more rapid than the increase in numbers of spermatozoa. Spermatocrit (Sct) was significantly lower in GnRHa-treated fish than in controls. Plasma levels of T and 11KT were elevated at 7 and 14 days p.i. in slightly spermiated fish treated with GnRHa and elevated plasma T and 11KT levels were accompanied by increased milt volume early in the spermiation period. In contrast, there was no significant difference in plasma T levels between GnRHa-treated and control fish in fish that were moderately spermiated at the time of implant. Treatment with GnRHa tended to result in lower plasma levels of 11KT and higher levels of 17,20hP relative to controls, and there was a positive 0044-8486/$ -see front matter D Aquaculture 240 www.elsevier.com/locate/aqua-online relationship between the elevation of plasma 17,20hP and the increase in milt volume in response to implantation of GnRHa pellet. Slow release GnRHa administration had no effect on sperm activity or pH and osmolality of seminal plasma in either experiment. D
Aquaculture Research, 2005
In spite of interest in the cultivation of the pejerrey fish Odontesthes bonariensis (Cuvier & Valenciennes 1835), there are few studies on subjects required to advance this activity. One of the problems is the synchronization of female and male maturation to provide eggs and sperm for larval production. The low volume of expressible milt, either in wild or culture fish, is a major problem. The aim of this work was to study the effectiveness of the administration of different hormones on sperm production in pejerrey. Milt production was enhanced by the injection of human chorionic gonadotropin (hCG) (16.7-fold increase, 625 IU kg−1), carp pituitary extracts (13.5-fold increase, 30 mg kg−1), salmon pituitary extracts (12.8-fold increase, 30 mg kg−1), salmon-type gonadotropin-releasing hormone analogue (GnRH) (16.7-fold increase, 10 μg kg−1) and mammalian-type GnRH analogue (10.8-fold increase, 20 μg kg−1). Sperm concentration, motility and the fertilization rate were not statistically different compared with control groups. It was also demonstrated that sperm could be obtained off-season. Taken together, hCG is recommended to stimulate pejerrey spermiation because it is effective in low doses is inexpensive and is widely available.
The aim of the present study is to investigate the effects of human chorionic gonadotropin (hCG), carp pituitary extract (CPE), melatonin, and adrenal gland extract (AE) administered either separately or in combination on the induction of testicular maturation and spermatogenesis in the thin-lipped grey mullet, Liza ramada, out of its spawning season. The results revealed that testes obtained from fish out of their reproductive season have empty seminiferous tubules with germ cells or Sertoli cells markers barely expressed and a low gonadsomatic index (GSI). A significant increase in GSI levels was observed by different hormone treatments. As predicted, hormone treatments showed an obvious stimulation of germ cells proliferation and testicular maturation as indicated by the immunohistochemical expression of germ cells and Sertoli cells markers with the highest values achieved by hCG/AE treatment. We conclude that hormone treatments may be a potential strategy for the induction of sp...
Aquatic Living Resources, 2001
The potential of carp pituitary powder (CPP) at one dose, or the luteinizing hormone-releasing hormone (LH-RH) analogue, des-Gly 10 ,(D-Ala 6 )-LH-RH-ethylamide, at three different doses to stimulate spermiation in paddlefish (Polyodon spathula) was tested. Single injections of the LH-RH analogue at 0.2, 0.1, or 0.05 mg·kg -1 increased the number of spermatozoa per kilogram of body weight (kg -1 b.w.) by 4.7, 3.4, and 3.4 times respectively compared to control, but the number of spermatozoa per kilogram of body weight decreased with CPP (4 mg·kg -1 ) by 1.7 times compared to the control. The LH-RH analogue prolonged active spermiation, with numbers of spermatozoa ranging from 7.69 to 1.19 × 10 9 kg -1 b.w. up to 96 h after treatment. Analysis of variance showed significant influence of experimental groups on volume of sperm per male and per kilogram of body weight, and the total number of spermatozoa per kilogram of body weight, but insignificant influence on the total number of spermatozoa per male. The percentage of motile spermatozoa was not different between experimental groups for sperm collection at different times after injection. A very high positive correlation (r = 0.93) was obtained between sperm concentration and sperm transmittance measured with a spectrophotometer. This relationship was described with the following linear regression: sperm concentration (× 10 9 mL -1 ) = 1.3244 X -0.9969 , where X is the percentage of sperm transmittance.
International Journal of Fisheries and Aquatic Studies, 2016
The aim of the present study is to investigate the effects of human chorionic gonadotropin (hCG), carp pituitary extract (CPE), melatonin, and adrenal gland extract (AE) administered either separately or in combination on the induction of testicular maturation and spermatogenesis in the thin-lipped grey mullet, Liza ramada, out of its spawning season. The results revealed that testes obtained from fish out of their reproductive season have empty seminiferous tubules with germ cells or Sertoli cells markers barely expressed and a low gonadsomatic index (GSI). A significant increase in GSI levels was observed by different hormone treatments. As predicted, hormone treatments showed an obvious stimulation of germ cells proliferation and testicular maturation as indicated by the immunohistochemical expression of germ cells and Sertoli cells markers with the highest values achieved by hCG/AE treatment. We conclude that hormone treatments may be a potential strategy for the induction of sp...
2000
In two separate spawning seasons, spermiating male Atlantic halibut were implanted with pellets containing gonadotrophin-releasing hormone agonist (GnRHa). Males were bled repeatedly, and milt samples were collected. Blood samples were assayed for free and conjugated steroids: testosterone, 11-ketotestosterone, 17,20α-dihydroxy-4-pregnen-3-one (17,20α-P), 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P), 17,20β,21-trihydroxy-4-pregnen-3one and steroids with a 17,20β configuration. Towards the end of the first season, pellets were implanted into three wild-caught and three hatchery-reared males. No control fish were available. The major progestogen in plasma was identified as sulphated 5β-pregnane-3β,17,20β-triol (3β,17,20β-P-5β-S). Concentrations of this steroid were stimulated by the GnRHa. Sulphated 17,20β-P was also identified in the plasma, but at 10-fold lower concentrations than 3β,17,20β-P-5β-S. In the middle of the second season, pellets were implanted into five hatchery-reared males; five unimplanted males were used as controls. Levels of androgens fell following GnRHa treatment, levels of progestogens rose briefly, and there was a significant increase in the fluidity of the milt. Of all the measured steroids, free and sulphated 17,20α-P showed the best correlation with milt fluidity.
Aquaculture, 1987
Induced spawning of maturing milkfish (Chinos chanos For&al) with gonadotropin-releasing hormone (GnRH) analogues administered in various ways. Aquaculture, 60: 303-310. The response of mature female captive milkfish to mammalian and salmon gonadotropinreleasing hormone analogues (mGnRH-A and sGnRH-A) was investigated. Prior to spawning, six groups of three females received (1) lo-16 B mGnRH-A from an osmotic pump implanted intraperitoneally (IP); (2) 100 M mGnRH-A from a cholesterol/cellulose pellet implanted IP; (3) 10 &kg mGnRH-A as an intramuscular (IM) injection; (4) lo-16 pg sGnRH-A from an osmotic pump implanted IP; (5) 100 B sGnRH-A from a cholesterol/cellulose pellet implanted IP, and (6) a cholesterol/cellulose pellet without armlogue implanted IP. The most effective treatment was 100 B sGnRH-A/fish given in a cholesterol/cellulose pellet; all (3/3) of the fish spawned. However, mGnRH-A was more effective (2/3) compared with sGnRH-A (l/3) if osmotic pumps were used to administer GnRH-A. If the dose and method of administration were not considered, then the sahnon and mammalian GnRH analogues were equally effective (62-67%) for induction of ovulation and natural spawning in milkfiih. Gonads of control fish regressed. At the doses tested, injections or pellet implantations were mom effective compared with osmotic pumps. All pellet-implanted and injected females responded to treatment and 75% (6/8) spawned; half (3/6) of the pump-implanted females spawned. Spawning occurred from 18 to 36 h after treatment.
Journal of Experimental Zoology, 1996
The role of gonadotropin-releasing hormone (GnRH) in spermiogenesis and spermiation is not well understood. This study examined the effects of different modes of administration of a GnRH analog (GnRHa; [~-Ala',Pro~NEtl-mGnRH) on spermiation in the sea bass, Dicentrarchus labrax. Groups of sea bass received either GnRHa injection in saline (I; 25 Kgkg body weight [BW] or one of three types of GnRHa sustained release polymeric device: a fastreleasing implant (ethylene-vinyl acetate copolymer [EVAcl; 100 pgkg BW), a slower-releasing implant (ethylene-vinyl acetate copolymer [EVSL]; 100 pg/kg BW), or biodegradable microspheres (M; 50 p g k g BW). Total expressible milt was collected and assessed for volume, motility, and counts at various intervals for 44 days. Untreated males produced a total of 9.4 k 3.4 ml/kg BW (mean rc_ SEM) of milt over the 44-day experimental period, with milt production ending by day 28. All GnRHa treatments stimulated a significant increase in total milt volume (mVkg BW) peaking by day 2 (I: 11.8 f 1.8) or day 7 (EVAc: 20.0 rc_ 1.5; M: 26.8 k 2.7; EVSL: 27.9 f 4.3) posttreatment.
Aquaculture, 2006
The aims of the present study were (a) to compare sperm quality (percentage of motile spermatozoa, motility duration, density and fertility after cryopreservation) between precocious and normally maturing male European sea bass Dicentrarchus labrax, (b) to examine the potential of human chorionic gonadotropin (hCG) to increase spermiation in precocious males and (c) to examine the potential of hCG to induce spermatogenesis and spermiation in non-precocious 1-year-old males. One hundred precocious and 100 non-precocious fish were each randomly divided in two groups each: control (precocious saline-treated and non precocious saline-treated) and treated (precocious hCG-treated and non precocious hCG-treated). Treated groups were administered weekly with 1000 IU hCG kg − 1 body weight while control groups were injected with physiological solution. Milt volume produced, sperm concentration, motility duration and fertilising ability were assessed every week in each group. The effect of the hormonal treatment on gonadal development was examined based on the gonadosomatic index and testicular histology. The results demonstrate that sperm produced by precocious fish has characteristics (mean value of motility class, mean maximum motility duration, concentration and fertility after cryopreservation) similar (P > 0.05) to those produced by 2-year-old fish. Human chorionic gonadotropin treatment in precocious fish resulted in a significant increase (P < 0.05) of milt volume, without affecting sperm quality. In non-precocious fish, hCG treatment resulted in greater percentage of spermiation (P < 0.05) compared to non-precocious saline-treated group. At the end of the trial (three weeks), 29 out of 50 non-precocious hCG-treated fish were spermiating and, within these 23 produced > 200 μl per fish of milt. No differences were observed in terms of sperm concentration, motility class, motility duration and fertilizing capacity due to hCG treatment in either precocious, or non-precocious fish. In addition, analysis of the testicular histology of fish that did not spermiate after hCG treatment, shows a significant (P < 0.05) enhancement of testicular development stages. The present study demonstrated that (a) precocious European sea bass males produce milt of comparable sperm characteristics to adult individuals, (b) treatment of nonprecocious males with hCG induced spermatogenesis and spermiation and (c) treatment of precocious males with hCG enhanced milt volume without affecting other sperm characteristics, including fertilizing ability.
Journal of Fish Biology, 2002
Spermiating male European sea bass Dicentrarchus labrax were treated with gonadotropinreleasing hormone agonists (GnRHa), either a GnRHa injection (IN; 25 g kg 1 body mass) or one of three types of controlled-release GnRHa-delivery systems: fast release implants (EVAc; 100 g kg 1 ), slow release implants (EVSL; 100 g kg 1 ) and slow release microspheres (MC; 50 g kg 1 ). Luteinizing hormone (LH) release was highly stimulated by all GnRHa treatments, with elevated plasma levels lasting for 2 days in injected fish (IN) and 2, 4 and 6 weeks in controlled-release-treated fish (EVAc, MC and EVSL, respectively), correlating with a 1, 3, 5 and 5 week period of stimulation of milt production, respectively. Plasma levels of the androgens testosterone (T) and 11-ketotestosterone (11-KT), were not significantly affected by the GnRHa treatments. Plasma T was high at early spermiation and declined sharply near the end of this period. Plasma 11-KT levels declined continuously throughout the experiment. Levels of 17,20 -dihydroxy-4-pregnen-3-one (17,20 -P), a proposed maturation-inducing steroid (MIS) in European sea bass, fluctuated around 0·2-1 ng ml 1 and were not greatly affected by the treatments. These results indicated a close correlation between sustained stimulation of LH release, achieved by GnRHa-delivery systems, and long-term enhancement of milt production. They also show an absence of changes in the common sex steroids, associated with elevated LH and enhanced spermiation. 2002 The Fisheries Society of the British Isles