LH-β and FSH-β mRNA expression in nesting and post-breeding three-spined stickleback, Gasterosteus aculeatus, and effects of castration on expression of LH-β, FSH-β and spiggin mRNA     

Anna Hellqvist  Monika Schmitz  Christina Lindberg  Per-Erik Olsson  Bertil Borg 《Fish physiology and biochemistry》2001,25(4):311-317

The mRNA expression of the LH- and FSH- subunits were measured in nesting and post-breeding male three-spined sticklebacks, Gasterosteus aculetaus, as well as in castrated and sham-operated nesting males. Furthermore, expression of an androgen induced kidney protein, spiggin, and 11-ketotestosterone (11KT) levels, were measured in the castrated and sham-operated males. Nesting males had significantly higher levels of both LH- and FSH- mRNA expression compared to post-breeding males. Furthermore, sham-operated males had significantly higher levels of LH- mRNA and spiggin mRNA expression than the castrated fish. Expression of FSH-, on the other hand, did not differ between castrated and sham-operated males. There were strong positive individual correlations between circulating levels of 11KT on the one hand and expressions of LH- and spiggin mRNA, whereas the correlation between 11KT levels and FSH- mRNA was weak. The negative effect of castration on -LH mRNA indicates that gonadal hormones stimulate this expression, whereas this was not the case for -FSH. The observed decline in -LH expression after the end of the breeding season may be the result of cessation of the gonadal stimulation of the pituitary. On the other hand, it is not likely that this can explain the decline in FSH- expression.  相似文献   

Effects of melatonin,p-chlorophenylalanine,and α-methylparatyrosine on plasma gonadotropin level and ovarian activity in the catfish,Heteropneustes fossilis: A study correlating changes in hypothalamic monoamines     

B. Senthilkumaran  K. P. Joy 《Fish physiology and biochemistry》1995,14(6):471-480

The effects of (ip, 10 injections over 20 days) of melatonin (75 g 100 g^–1 BW), the serotonin (5-HT)-synthesis blocker, para-cholorophenylalanine (p-CPA, 10 mg 100g^{–1 BW}) and the catecholamine-synthesis blocker, -methylparatyrosine (-MPT, 10 mg 100 g^–1 BW) on gonadotropin (GTH) secretion and ovarian activity were studied in ^{Heteropneustes fossilis} during late preparatory to early prespawning (April–May). The treatments resulted in significant reductions of plasma GTH and estradiol-17 levels, the gonadosomatic index, frequency distribution of vitellogenic and postvitellogenic oocytes, and ovarian and serum ³²p-labelled alkali-labile phosphoprotein (a marker of vitellogenic activity). Most of the oocytes were nonvitellogenic or had undergone atretic changes. The hepatic ³²-phosphoprotein content increased significantly over the saline control value. The effects were similar and pronounced in the p-CPA and melatonin-treated groups but were moderate in the -MPT-treated group. Hypothalamic 5-HT content and turnover were significantly inhibited in the p-CPA and melatonin-treated groups but the content and turnover of catecholamines were not. The -MPT treatment decreased significantly the content and turnover of dopamine (DA), noradrenaline (NA), and adrenaline (A) but did not influence the 5-HT content or turnover. These results suggest that 5-HT, NA and A are stimulatory to GTH secretion and that melatonin may act on the serotonergic system to inhibit the pituitary-gonadal axis.to whom correspondence should be addressed.A part of the results was presented at the International Workshop on Pineal gland: Its molecular signals and published as an abstract in Neuroendocrinol. Lett. 14: 399 pp., 1992.  相似文献   

Effects of exogenous neurohormone, gonadotropin (GtH) and dopaminergic drugs on the serum GtH content and ovulatory responsiveness of wild catfish, Silurus asotus (Linnaeus, 1758)     

H Sh Wen  & H R Lin 《Aquaculture Research》2004,35(2):204-212

Wild female catfish Silurus asotus (Linnaeus, 1758) were injected with domperidone (DOM) alone, [d ‐Ala⁶, Pro⁹ Net]‐luteinizing hormone‐releasing hormone (LHRH‐A) alone once or twice, LHRH‐A plus DOM once or twice simultaneously at 6‐h intervals, LHRH‐A plus carp pituitary extract (CPE) twice simultaneously at 6‐h intervals and LHRH‐A plus human chorionic gonadotropin (HCG) twice simultaneously 6 h apart respectively. The results indicated that injection of LHRH‐A at a dosage of 0.01–0.02 μg g^?1 body weight (BWt) alone induced a low but significant increase in serum gonadotropin (GtH) (P<0.05) and resulted in a very low ovulation rate, while DOM at a dosage of 5 μg g^?1 BWt alone did not induce an increase in the serum GtH levels and ovulation; in contrast, LHRH‐A at a dosage of 0.01 μg g^?1 BWt plus DOM at a dosage of 5 μg g^?1 BWt (termed the Linpe technique) increased the serum GtH (P<0.05) significantly and induced an ovulatory rate of 100%, while LHRH‐A plus CPE or HCG resulted in an increase in the serum GtH (P<0.05) and high ovulatory rate, although the latency period was longer when fish were given LHRH‐A plus HCG or CPE.  相似文献   

Control of ion transport by the sperm duct epithelium of brook trout (Salvelinus fontinalis)     

William S. Marshall  Sharon E. Bryson  David R. Idler 《Fish physiology and biochemistry》1989,7(1-6):331-336

The sperm duct epithelium of brook trout (Salvelinus fontinalis), mountedin vitro in Ussing-style epithelial chambers actively absorbs Na⁺ (measured as the short-circuit current, I_sc) and secretes K⁺ (measured using⁸⁶Rb⁺ as tracer). Dibutyryl-cyclic-adenosine monophosphate (db-cAMP) and 3-isobutyl-1-methylxanthine (IMX) produce a rapid, sustained stimulation of both ion transport processes, but the hormone connected to the response is unknown. Purified sockeye salmon CON A2 gonadotropin (GtH) produces a dose-dependent, rapid and sustained rise in Na⁺ uptake and K⁺ secretion. The time course, electrophysiological and transport characteristics are similar to those evoked by IMX. Carbohydrate-poor (chum salmon CON A1) GtH is ineffective. Pretreatment of fish with 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P) significantly increases milt volume but is without effect on resting or stimulated (IMX + db-cAMP) levels of sperm duct ion transport. This is the first indication of a direct, rapid action of GtH on ion transport by the vertebrate blood-testis barrier. The results suggest direct involvement of GtH in control of later stages of sperm maturation.  相似文献   

Involvement of steroid hormones in the preovulatory gonadotropin surge in female goldfish     

Makito Kobayashi  Katsumi Aida  Isao Hanyu 《Fish physiology and biochemistry》1989,7(1-6):141-146

Goldfish,Carassius auratus, spawn several times within a spawning season. A gonadotropin (GtH) surge occurs at the time of ovulation in this cyprinid species. This ovulatory GtH surge mediates the processes of final oocyte maturation and ovulation, and occurs at the end of each spawning cycle. Within a cycle, there is a shift in the predominant plasma steroid from estradiol to testosterone, and finally 17α, 20β-dihydroxy-4-pregnen-3-one at the time of the ovulatory GtH surge. High levels of testosterone were always observed before ovulation. When ovariectomized or sexually regressed female goldfish were implanted with testosterone, they exhibited a GtH surge which was similar to those normally observed at ovulation. These results strongly suggest that elevated plasma testosterone is an important physiological requirement for the occurrence of the GtH surge.  相似文献   

Reproductive parameters of the chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis> estimated from human chorionic gonadotropin-induced final oocyte maturation and ovulation in captivity     

Tetsuro?Shiraishi  Kohei?Ohta  Akihiko?Yamaguchi  Mari?Yoda  Hisashi?Chuda  Michiya?MatsuyamaEmail author 《Fisheries Science》2005,71(3):531-542

ABSTRACT:   Final oocyte maturation and ovulation of captive chub mackerel Scomber japonicus with fully yolk-accumulated oocytes were induced by a single injection of human chorionic gonadotropin. Reproductive parameters, including spawning frequency and batch fecundity, which are required to estimate spawning biomass in pelagic fish by the daily egg production method, were analyzed. Germinal vesicle migration (GVM) occurred at 18–24 h post-injection, and the hydration and ovulation of oocytes were completed at 30 and 36 h post-injection, respectively. The results of the maturation process suggest that fish with GVM-stage ovaries captured in the daytime from the field are capable of spawning on the night following their capture. The oocytes used in the oocyte size-frequency distribution method for batch fecundity estimates should be at late GVM and more advanced stages. The results of sequential artificial insemination showed that the quality of ovulated eggs held in the ovarian lumen rapidly deteriorated as time progressed after ovulation. This indicates that the fertilization window for the ovulated eggs of chub mackerel lasts only a few hours, and spawning behavior should be performed within a few hours after ovulation in the wild population.  相似文献   

Isolation of pituitary glycoprotein gonadotropins from the grass carp (Ctenopharyngodon idell)     

J. Y. L. Yu  S. T. Shen 《Fish physiology and biochemistry》1989,7(1-6):177-183

Gonadotropins (GTH) were isolated from pituitary glands of grass carp and their properties investigated. Acetone-dried pituitaries were extracted with ammonium acetate-ethanol and were then passed through cation exchanger, anion exchanger, and gel filtration column. Two glycoprotein gonadotropins (DE I and DE II) were isolated of MW 56,000 and 53,000 daltons, respectively, as determined by gel filtration technique. Isoelectric points of the two GTHs also differed from each other. Sialic acid contents were 3.64% and 1.47% for DE I and DE II, respectively. Both GTH's stimulated, in a similar manner, testicular androgen and ovarian estradiol synthesisin vitro.  相似文献   

Effects of (D-Ala6, Pro9N ethylamide) — LHRH on plasma levels of gonadotropin, 17α,20β-dihydroxy-4-pregnen-3-one and testosterone in male goldeye (hiodon alosoides Rafineque)     

N. W. Pankhurst  G. van der Kraak  R. E. Peter  B. Breton 《Fish physiology and biochemistry》1986,1(3):163-170

Male goldeye were treated with (D-Ala⁶, Pro⁹-N ethylamide) — LHRH (LHRH-A) in saline or a silastic pellet (100 µg.kg^–1 body weight) and changes in plasma gonadotropin (GtH), 17,20-dihydroxy-4-pregnen-3-one (17,20P) and testosterone (T) levels were determined by radioimmunoassay. LHRH-A increased plasma GtH levels, with the response to LHRH-A in saline being of much greater magnitude and duration than the response to silastic pellet implants. Seasonal differences were found in the response to LHRH-A. Spermiated fish were the most responsive, recrudescing fish the least, and regressed fish displayed an intermediate response. Plasma 17,20P levels were elevated in response to LHRHA in fish of all sexual stages although the magnitude of the increase was not related to the magnitude of the increase in GtH levels. Treatment with LHRH-A also resulted in a transitory increase in plasma T levels. The endocrine control of GtH and steroid secretion in goldeye is discussed in relation to studies in cyprinids and salmonids. Address for reprint requests: Department of Zoology, University of Alberta, Edmonton, Alberta T6G 2E9 Canada.  相似文献   

Direct actions of serotonin on gonadotropin-II and growth hormone release from goldfish pituitary cells: interactions with gonadotropin-releasing hormone and dopamine and further evaluation of serotonin receptor specificity     

A.O.L. Wong  C.K. Murphy  J.P. Chang  C.M. Neumann  A. Lo  R.E. Peter 《Fish physiology and biochemistry》1998,19(1):23-34

In this study, the direct actions of serotonin (5HT) on gonadotropin (GTH)-II and growth hormone (GH) release in the goldfish were tested at the pituitary cell level. 5HT (10 nM - 10 µM) stimulated GTH-II but inhibited GH release from perifused goldfish pituitary cells in a dose-dependent manner. The minimal effective dose of 5HT tested to suppress basal GH secretion (10 nM) was 10-fold lower than that to stimulate GTH-II release (100 nM). The GTH-II releasing effect of 5HT was abolished by repeated 5HT treatment (10 µM) whereas the corresponding inhibition on GH release was unaffected. These results suggest that 5HT receptors on goldfish gonadotrophs and somatotrophs exhibit intrinsic differences in terms of sensitivity to stimulation and resistance to desensitization. Salmon GTH-releasing hormone (sGnRH, 100 nM) stimulated GTH-II and GH release from goldfish pituitary cells. The GTH-II releasing action of sGnRH was unaffected by simultaneous treatment of 5HT (1 µM). However, the corresponding GH response to sGnRH (100 nM) was inhibited. In the goldfish, dopamine is known to stimulate GH release through activation of pituitary D1 receptors. In the present study, the GH-releasing action of dopamine (1 µM) and the D1 agonist SKF38393 (1 µM) was significantly reduced by 5HT (1 µM). To examine the receptor specificity of 5HT action, the effects of 5HT1 and 5HT2 analogs on GTH-II and GH release were tested in goldfish pituitary cells. The 5HT1 agonist 8OH DPAT (0.1 and 1µM) and 5HT2 agonist methyl 5HT (0.1 1µM) mimicked the GTH-II releasing effect of 5HT. The 5HT1 agonist 8OH DPAT (0.1 and 1µM) also stimulated GH release but the 5HT2 agonist methyl 5HT (0.1 and 1µM) was inhibitory to basal GH secretion. In addition, 5HT (1µM) -stimulated GTH-II release was abolished by the 5HT1 antagonist methiothepin (10µM) and 5HT2 antagonist mianserin (10µM). Similarly, the inhibitory action of 5HT (1µM) on basal GH release was blocked by the 5HT2 antagonist mianserin (10µM). The 5HT1 antagonist methiothepin (10µM) was not effective in this regard. These results, taken together, indicate that 5HT exerts its regulatory actions on GTH-II and GH release in the goldfish directly at the pituitary cell level, probably through interactions with other regulators including sGnRH and dopamine. The GTH-II releasing action of 5HT is mediated through 5HT2 and possibly 5HT1 receptors. The inhibition of 5HT on basal GH release is mediated through 5HT2 receptors only. Apparently, 5HT1 receptors are not involved in this inhibitory action. In this study, a paradoxical stimulatory component of 5HT on GH release by activating 5HT1 receptors is also implicated.  相似文献   

Binding characteristics and regulation of the 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) receptor on testicular and sperm plasma membranes of spotted seatrout (Cynoscion nebulosus)     

P. Thomas  D. Breckenridge-Miller  C. Detweiler 《Fish physiology and biochemistry》1997,17(1-6):109-116

The binding characteristics of 17,20,21-trihydroxy-4-pregnen-3-one (20-S) to plasma membranes prepared from the testes and sperm of spotted seatrout (Cynoscion nebulosus) were investigated using a filtration method to retain the bound 20-S. A single class of high affinity (K_d = 17.9 nM), low capacity (B_max = 0.072 nM g^-1 testes) binding sites was identified by saturation and Scatchard analyses on testicular membranes of spermiating spotted seatrout. A corresponding receptor (K_d = 22.17 nM, B_max = 0.00261 nM ml^-1 milt) was also detected in spermatozoan membrane preparations. The rates of 20-S association and dissociation were rapid, both had T_halfs of less than 1 min. Competition studies indicated that the receptor was highly specific for 20-S. 17,20-dihydroxy-4-pregnen-3-one, which had the highest affinity of the other steroids tested, had a relative binding affinity (RBA) of 14.3%. Progesterone, 11-deoxycortisol and testosterone competed with an order of magnitude less affinity (RBA's of 7.4, 1.8 and 1.1%, respectively). Estradiol displayed low affinity for the receptor (RBA = 0.4%) and cortisol did not cause any displacement at 1000-fold excess concentration. Specific 20-S receptor binding was detected in plasma membranes from testes of both spermiating and non-spermiating seatrout and on spermatozoa. Prolonged incubation of testicular fragments from a spermiating fish with gonadotropin (15 IU ml^-1 human chorionic gonadotropin) or forskolin (10 µM) caused a 2–3 fold increase in membrane receptor binding. Previous studies have shown that gonadotropin-induced upregulation of the 20-S plasma membrane receptor in seatrout ovaries is required for the oocytes to become responsive to 20-S and undergo final maturation. The existence of a 20-S membrane receptor on sperm and its upregulation in the testes by gonadotropin raises the possibility that final maturation of spermatozoa in male seatrout may be regulated by a similar mechanism.  相似文献