Effect Of Luteinizing Hormone-releasing Hormone Analogue Research Articles

The effect of LHRHa with and without dopamine antagonist on reproductive performance in lambari Astyanax altiparanae

The present study evaluated the effect of luteinizing hormone-releasing hormone analogue (LHRHa) with and without dopamine antagonist (i.e., domperidone (D)) on the reproductive performance of lambari females (Astyanax altiparanae) as well as on secretion of 17α-20β-dihydroxy-4-pregnen-3-one (17,20β-P) and prostaglandin F2α (PGF2α)) and on the histological evaluation of ovarian structures in two independent and consecutive experiments. In the first experiment (Exp. 1), five LHRHa doses (20, 60, 180, 540, and 1620 μg/kg BW) were tested with three replicates each, while in the second experiment (Exp. 2) the dose of 180 μg/kg was tested in combination with D at a dose of 20 mg/kg with four replicates. The replicates in both experiments consisted of an experimental unit in which five females and 10 males were placed. In both experiments, two control groups were formed, 0.9% saline (negative control) and 6 mg/kg of carp pituitary homogenate (CPH), and females from all groups received the total dose in two injections (i.e., one comprising 10% of the total dose and a second one 12 h later comprising the resolving dose). There was a decrease in fertilization and hatching rates that coincided with the two highest doses of LHRHa (540 and 1620 μg/kg), suggesting that these doses may have caused hormonal overstimulation affecting egg quality. Taken together, these results were not in favor of an obvious dopaminergic control of final oocyte maturation (FOM) in lambari, since the use of LHRHa associated with D did not improve reproductive performance of lambari compared to LHRHa alone, CPH, and negative control. Plasma levels of 17,20β-P were related to FOM and/or ovulation in most cases. There was not a clear association between ovulation and PGF2α plasma levels. The CPH-treated group was the only one performing better than the negative control, increasing the spawning rate and spawning volume per female body mass as well as triggered FOM in almost all females submitted to hormonal induction, indicating that CPH is the most suitable hormonal therapy to induce FOM and ovulation in lambari (among the treatments tested here).

Molecular cloning of vasa gene and the effects of LHRH-A on its expression in blue tilapia Oreochromis aureus

The full length of vasa cDNA in blue tilapia Oreochromis aureus was cloned and sequenced using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). Nucleotide sequence analysis revealed that the cDNA contained 2,143 bp and was consisted of a 48-bp 5' untranslated terminal region (5'-UTR), a 157-bp 3' untranslated terminal region (3'-UTR) and a 1,938-bp open reading frame (ORF) which encoded 645 amino acids. Homological protein analysis showed that vasa in O. aureus was highly conserved with Nile tilapia Oreochromis niloticus. Tissue distribution expression analysis indicated that vasa was specifically expressed in the gonads. Using in situ hybridization, we found that vasa was expressed in spermatogonia and spermatocytes rather than spermatids and sperm. In order to examine the influence of luteinizing hormone releasing hormone analog (LHRH-A) on vasa, the in vivo injections were performed different concentrations of LHRH-A. Our results showed that LHRH-A induced meiosis and down-regulated vasa mRNA expression. In summary, our results showed that vasa was specifically expressed in gonads and LHRH-A inhibited vasa expression in the testis. Our results also suggested that LHRH-A could regulate vasa gene expression in O. aureus testis.

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.

Long-term treatment of central precocious puberty with an intranasal LHRH analogue: control of pituitary function by urinary gonadotropins

Daily subcutaneous doses of luteinizing hormone-releasing hormone (LHRH) analogues are a well-established therapy for gonadotropin-dependent precocious puberty. Reports on intranasally administered analogues, however, are controversial. We studied the effect of intranasal D-Ser(TBU)6-LHRH(BUS) on growth rate, skeletal maturation, and urinary gonadotropins in five girls and one boy with central precocious puberty (CPP) who had been treated for 1.4-2.3 years (mean 1.9). Because of the potential antifertility effects of LHRH analogues, testicular histology was analysed in the boy. In the five children with accelerated growth, the bone age-related velocity of height gain decreased from 10.58 +/- 2.77 to 5.82 +/- 1.8 cm/year (means +/- SD, P less than 0.01), and the ratio of change in bone age to change in chronological age fell below 1. Basal luteinizing hormone (LH), and LHRH-stimulated LH and follicle stimulating-hormone, at pubertal levels before treatment, decreased significantly in all children, normalizing in four (P less than 0.04). During therapy, pituitary function was best controlled by urinary LH, which correlated with clinical data. After 13 months of therapy, testicular histology showed degenerated Sertoli cells, and absence of B- and Ap-spermatogonia and of primary spermatocytes in the boy. We conclude that: (1) Efficient long-term suppression of central precocious puberty--including accelerated growth and skeletal maturation--can be maintained by intranasal dosage of BUS. (2) Urinary LH reflects pituitary function and proves to be a reliable guide to adjustment of the LHRH-analogue dose regimen.(ABSTRACT TRUNCATED AT 250 WORDS)

Luteinizing Hormone - Releasing Hormone Analogs: Female Contraception

Exploration of the potential uses of luteinizing hormone-releasing hormone (LHRH) analogs in contraception has involved inhibition of ovulation of implantation and luteolysis. LHRH analogs when given chronically have the paradoxical effect of down-regulating or desensitizing LHRH receptors in the pituitary raising LH and FSH levels and producing a hypogonadal state. Studies in rhesus monkeys have documented that LHRH given in the early follicular phase block follicular growth and delay ovulation. In women the LHRH analog 4f-Antag given sc also prolonged follicular phase but had no effect on luteal phase. Several LHRH analogs have effectively inhibited ovulation in women: Buserelin Naferelin Leuprolide ad D-TRP. While ovulation is consistently blocked some women experience amenorrhea some oligomenorrhea and some menstruation-like bleeding. Estrogen levels resemble follicular phase levels but the degree of gonadotropin suppression varied from hypoestrogenic conditions of vasomotor symptoms and atrophic vagina to a potential for endometrial hyperplasia. Combined treatments with LHRH analogs and progestins norethisterone or medroxyprogesterone acetate have been tested to induce withdrawal bleeding and prevent endometrial build-up. Another problem with these experimental ovulation-inhibiting treatments is that the intranasal spray route produced variable absorption but the daily injections are not practical. Long-acting implants or injections are being formulated. Conflicting results have appeared in studies on the possible luteolytic effect of LHRH analogs. Work in rhesus monkeys and in women suggests that a narrow window of time is required to get a luteolytic effect. Multiple doses or chronic administration of LHRH analogs will terminate early pregnancy in small animals and nonhuman primates. No effect on implantation has been reported in the few small trials in women to date.