Productive and reproductive performance of crossbred dairy heifers with induced lactation and efficacy of antimicrobial therapy associated with internal teat sealants / Desempenho produtivo e reprodutivo de novilhas com lactação induzida e eficácia da terapia antimicrobiana associada com selante interno de tetos

This study evaluated (a) the efficacy of an association between injectable antibiotic therapy and sealant (ATBS) on milk yield (MY), somatic cell count (SCC), and prevalence of intramammary infections (IMI); and (b) the efficacy of gonadotropin-releasing hormone (GnRH) on follicular cyst (FCs) resolution (cyclicity at the 45th day in milk; DIM) and cumulative pregnancy rate (CPR) in heifers submitted to a lactation induction protocol (LIP). A total of 114 crossbred (Holstein × Jersey) heifers, with 34.7 ± 4.8 months and 439 ± 56.35 kg were submitted to LIP. On the 5th day of the LIP, the heifers were assigned to (i) ATBS (n = 57) with 7 mg/kg of norfloxacin associated with sealant and (ii) Control 1 (n = 57; CONT1) with no treatments. Lactation began on the 21st day of LIP and the 15th DIM, FCs were diagnosed and 106 heifers were randomized into two treatment groups with 53 heifers each: (i) GnRH (5 mL injectable GnRH) and (ii) Control 2 (CONT2; no treatment). Of the 114 heifers initially induced, 83.33% (n = 95) responded to LIP with an average MY of 15.19 kg/milk/day during 22 weeks of lactation. In the first 14 DIM, the IMI prevalence was 18% and 28% for heifers ATBS and CONT1 treated, respectively. Additionally, coagulase-negative Staphylococcus was the most frequently isolated group of pathogens. Mammary quarters that received ATBS treatment had a lower risk of IMI and SCC than CONT1. The cyclicity at 45 DIM was 68% (ATBS) and 35% (CONT1), and 57% and 46% for animals in the GnRH and CONT2. CPR was 60% in the ATBS group and 89% in CONT1, but GnRH treatment did not affect the CPR. In conclusion, LIP was effective in stimulating MY in heifers, and the IMI prevalence decreased with ATBS treatment. Also, the use of GnRH did not affect the FC regression, cyclicity at 45 DIM, and CPR.(AU)

Este estudo avaliou a (i) eficácia da associação entre antibioticoterapia injetável e selante interno de tetos (ATBS) na produção de leite (PL), contagem de células somáticas (CCS), e prevalência de infecções intramamárias (IIM); e (ii) eficácia do hormônio liberador de gonadotrofina (GnRH) na resolução de cistos foliculares (CFs), ciclicidade ao 45º dia em lactação (DEL) e taxa de prenhez cumulativa (TPC) em novilhas submetidas a um protocolo de indução de lactação (PIL). Um total de 114 novilhas mestiças (Holandês × Jersey), com 34,7 ± 4,8 meses e 439 ± 56,35 kg foram submetidas ao PIL. No 5º dia do PIL, as novilhas receberam: (i) ATBS (n = 57) com 7 mg/kg de norfloxacina associada ao selante interno de tetos e (ii) Controle 1 (n = 57; CONT1) sem tratamento. A lactação teve início no 21º dia do PIL e no 15º DEL, foram diagnosticados CFs e 106 novilhas foram agrupadas em dois grupos de tratamento com 53 novilhas em cada: (i) GnRH (5 mL de GnRH injetável) e (ii) Controle 2 (CONT2; sem tratamento). Das 114 novilhas inicialmente induzidas, 83,33% (n = 95) responderam ao PIL com PL média de 15,19 kg/leite/d durante 22 semanas de lactação. Nos primeiros 14 DEL a prevalência de IIM foi de 18% e 28% para as novilhas tratadas com ATBS e CONT1, respectivamente. Além disso, estafilococos coagulase negativa foram o grupo de patógenos mais frequentemente isolados. Quartos mamários tratados com ATBS tiveram menor risco (0,56) de IIM e menor CCS do que CONT1. A ciclicidade a 45 DEL foi de 68% (ATBS) e 35% (CONT1), e 57% e 46% para os animais no GnRH e CONT2. A TPC foi de 60% no grupo ATBS e 89% no CONT1, porém o tratamento com GnRH não afetou a TPC. Em conclusão, o PIL foi eficaz em estimular a PL em novilhas tardias e a prevalência de IIM diminiuiu com o tratamento ATBS. Além disso, o uso de GnRH não afetou a regressão de CF, ciclicidade em 45 DEL e a TPC.(AU)

Fresh, equilibrated and post-thaw sperm quality of Brycon orbignyanus (Valenciennes, 1850) and Prochilodus lineatus (Valenciennes, 1837) treated with either salmon GnRHa and domperidone or pituitary extract

The effects of reduced doses of Ovaprim™ (GnRHa + domperidone) on sperm release of Brycon orbignyanus and Prochilodus lineatus were evaluated. Furthermore, sperm quality was compared among fresh, equilibrated and post-thaw samples. Males received a single and reduced dose of Ovaprim™ (0.125 or 0.25 ml/kg); control males received pituitary extract (cPE; 3 mg/kg). Fresh sperm was evaluated for volume, concentration, seminal plasma osmolality and seminal plasma pH. Then sperm was diluted in a freezing medium, equilibrated for 15-20 min and frozen in nitrogen vapor vessel (dry-shipper). Sperm motility was analyzed during 60 s post-activation in fresh, equilibrated and post-thaw samples. Sperm quality of males treated with Ovaprim™ (both doses) were not different from that of cPE-treated males, thus these data were pooled. In B. orbignyanus, motility was higher in fresh (99%) than in equilibrated sperm (81%); post-thaw motility dropped to 42%. In P. lineatus, motility was similar in fresh (99%) and equilibrated sperm (92%); post-thaw motility was 73%. Motility decreased as a function of time post-activation, and this decrease was significant after 60 s in fresh and equilibrated sperm, and as soon as 30 s in post-thaw sperm, in both species. Ovaprim™ at 1/4 of the recommended dose can successfully replace cPE.

O efeito de doses reduzidas de Ovaprim® (GnRHa + domperidona) na liberação do sêmen de Brycon orbignyanus e Prochilodus lineatus foi avaliado. Além disso, a qualidade do sêmen foi comparada entre as amostras frescas, equilibradas e descongeladas. Os machos receberam dose única e reduzida de Ovaprim® (0,125 ou 0,25 ml/kg); os machos-controle receberam extrato de hipófise (cPE; 3 mg/kg). O sêmen fresco foi avaliado quanto ao volume, concentração, e osmolalidade e pH do plasma seminal. Em seguida, o sêmen foi diluído num meio de congelamento, equilibrado por 15-20 min e congelado em botijão de vapor de nitrogênio (dry-shipper). A motilidade espermática foi analisada durante 60 s pós-ativação no sêmen fresco, equilibrado e descongelado. A qualidade do sêmen não diferiu entre os machos tratados com Ovaprim® (ambas as doses) ou cPE, assim foi feito um pool desses dados. Em B. orbignyanus, a motilidade foi maior no sêmen fresco (99%) do que no equilibrado (81%); a motilidade do sêmen descongelado caiu para 42%. Em P. lineatus, a motilidade foi semelhante entre o sêmen fresco (99%) e equilibrado (92%); a motilidade do sêmen descongelado foi 73%. A motilidade caiu em função do tempo pós-ativação, e essa queda foi significante após 60 s no sêmen fresco e equilibrado, e tão precoce quanto 30 s no sêmen descongelado, em ambas as espécies. Ovaprim® a 1/4 da dose recomendada pode substituir o cPE com sucesso.

Recovery pattern of hypothalamo-pituitary-testicular axis in patients with macroprolactinomas after treatment with cabergoline.

Background & objectives: Hyperprolactinaemia affects testicular functions by influencing hypothalamo-pituitary-testicular (HPT) axis at various levels. Available literature on the level of defect, time course of improvement of gonadal functions and its relation with decline in prolactin levels is scanty. We carried out this study to evaluate the HPT axis in patients with macroprolactinomas, before and six months after cabergoline therapy. Methods: Fifteen men with macroprolactinomas underwent gonadotropin and testosterone response to their respective stimuli before and after six months of cabergoline therapy. Results: Serum prolactin levels decreased after six months of therapy. Pretreatment, mean lutenizing and follicle stimulating hormones (LH and FSH) levels were 2.0 ± 0.4 and 1.4 ± 0.2 IU/l, respectively. However, LH and FSH responses to GnRH were preserved in majority of the patients and LH peaked to 12.1 ± 2.3 IU/l (P<0.01), while FSH to 2.9 ± 0.4 IU/l suggesting the influence of hyperprolactinaemia at the level of hypothalamus with preserved gonadotrope reserve. After cabergoline therapy, there was an increase in basal as well as stimulated LH and FSH levels, though these were not statistically significant when compared to respective pretherapy levels. Basal testosterone (T) levels significantly improved after therapy, but peak T response to hCG was similar at both pre- and post treatment. A significant correlation was observed between peak LH and peak T at baseline (r=0.53, P<0.01) and it further strengthened after therapy (r=0.70, P<0.01). After cabergoline therapy, there was significant improvement in seminal volume, sperm count and motility and sperm count correlated with peak FSH response (r=0.53, P<0.05). Interpretation & conclusions: Hyperprolactinaemia affects testicular functions probably by influencing at the level of hypothalamus resulting in subnormal basal secretion of gonadotropins required for optimal testicular functions.

effect of LH and GnRH analogues on induction ovulation in Bactrian camel [Camelus bactrianus]

Ovarian follicle response and corpus luteum formation following induction of ovulation using gonadotropin-releasing hormone [GnRH] analogues and luteinizing hormone [LH] in Bactrian camel were characterized. Bactrian camels with a mature follicle [13-19.6 mm] received: 1] natural porcine LH [25 mg, IV, n = 4], 2] Buserelin [20 microg, IV, n = 4] and 3] Alarelin [25 microg, IM, n = 4]. Daily ultrasonography and blood samplings were conducted between day -3 and +15 of the experiment [day 0 = Induction of ovulation]. Data were analyzed by univariat analysis with repeated measures analysis included in the model. Following treatment, mature follicle ovulated within 2 days and a new follicle wave emerged after 2-3 days. New mature follicle reached a size of 13.5 +/- 0.14 mm by day 12. Corpus luteum was detected on day 6 and reached the maximum size of 19.73 +/- 0.81 mm on day 9. Progesterone concentration initiated to increase on day 5, reached maximum concentration on day 9 and decreased significantly on day 11. In conclusion, due to the lack of significant difference among treatment groups [P>0.05], Alarelin may be considered as a drug of choice for inducing ovulation in Bactrian camel because of its effectiveness, simple route of administration [IM vs. IV], lower price, and local availability

Effect of Ovaprim doses and latency periods on induced spawning of Clarias batrachus: observation on larval deformity.

Induced spawning of C. batrachus was conducted at different Ovaprim dose and latency period combinations to observe the deformed larvae among the hatchlings. For the purpose, four doses of Ovaprim (0.5, 1.0, 1.5 and 2.0 ml/kg body weight) and five latency periods (11, 14, 17, 20 and 23 hr) were considered in 20 different combinations. There were no deformed larvae in the females injected with all four doses and stripped at 11 hr latency, as the eggs did not hatch. The percentage of deformed larvae (4-7%) did not vary significantly at 1.0-2.0 ml dose level in combination with 14-17 hr latency periods. While increasing the latency period beyond 17 hr at 1-1.5 ml dose level, the percentage of deformed larvae increased significantly and touched as high as 11%. The results indicated that 1-1.5 ml dose in combination with 14-17 hr latency are suitable to reduce the deformed larvae among the hatchlings during induced spawning of C. batrachus.

Effect of GnRH on guinea pig endometrium at preimplantation stage.

Endometrium of GnRH treated group resembled with pregnant group and endometrial thickness in these groups significantly increased in comparison with non-pregnant group. In GnRH treated animals, most of histomorphological changes in epithelial cells, glands and stroma of uterus was similar to pregnant group. The results revealed that mammalian form of GnRH exerted endometrial change in guinea pig almost similar to those occur in normal pregnant animals and its administration prior to implantation may improve pregnancy rate following embryo transfer.

Influence of GnRH Agonist and Neural Antagonists on Stress-blockade of LH and Prolactin Surges Induced by 17 beta-estradiol in Ovariectomized Rats

In our previous study, we demonstrated that immobilization stress blocked estrogen-induced luteinizing hormone(LH) surge possibly by inhibiting the synthesis and release of gonadotropin-releasing hormone (GnRH) at the hypothalamic level and by blocking estrogen-induced prolactin (PRL) surge by increasing the synthesis of dopamine receptor at the pituitary level in ovariectomized rats. The present study was performed to determine whether immobilization stress affects pituitary LH responsiveness to GnRH, and whether endogenous opioid peptide (EOP) and dopamine systems are involved in blocking LH and PRL surges during immobilization stress. Immobilization stress was found to inhibit basal LH release and to completely abolish LH surge. However, the intravenous application of GnRH agonist completely restored immobilization-blocked LH surge and basal LH release. Treatment with naloxone did not exert any effect on immobilization-blocked LH surge but increased basal LH release during immobilization stress. Pimozide did not affect immobilization-blocked LH surge or basal LH release. Naloxone also decreased immobilization-induced basal PRL release, but had no effect on immobilization-blocked PRL surge. Immobilization-increased basal PRL levels were augmented by pimozide treatment and immobilization-blocked PRL surge was dramatically restored by pimozide. We conclude that immobilization stress does not impair pituitary LH response to GnRH, and that the immobilization stress-induced blockage of LH surge is probably not mediated by either the opioidergic or the dopaminergic system. However, immobilization-blockade of PRL surge may be partly mediated by the dopaminergic system.

Regulation of gonadotropin releasing hormone receptor mRNA expression in cultured rat granulosa cells

The homologous regulation of pituitary Gonadotropin Releasing Hormone Receptor (GnRH-R) mRNA expression by GnRH has been well demonstrated. However, the regulation of the ovarian GnRH-R is poorly understood. The present study was performed to demonstrate the presence of GnRH transcripts in addition to GnRH-R mRNA and the regulation of GnRH-R mRNA expression in the granulosa cells isolated from small antral follicles. The GnRH and GnRH-R mRNA levels were determined by a competitive reverse transcription-polymerase chain reaction (RT-PCR). The granulosa cells were obtained from immature rats implanted with diethylstilbestrol for 3 days. When GnRH transcript expression was examined in isolated granulosa cells by RT-PCR, the PCR products showed two bands. The larger band contained intronic sequences and the smaller band was a fully processed GnRH gene transcript identical to hypothalamic GnRH. This suggests that authentic GnRH gene transcripts are expressed in ovarian granulosa cells and may act on the granulosa cells in a paracrine or autocrine manner. Since GnRH action in the granulosa cells is mediated by specific GnRH-R, it is of interest to examine whether GnRH-R is synthesized in the granulosa cells. When the granulosa cells were cultured in media only, GnRH-R mRNA levels increased abruptly within 3 h and gradually decreased thereafter during the 24 h culture period. However, GnRH itself did not alter the GnRH-R mRNA expression levels in cultured granulosa cells. Interestingly, treatment with FSH decreased the GnRH-R mRNA levels in a dose-dependent manner. A time-course analysis revealed that the GnRH-R mRNA levels were significantly lower up to 9 h after FSH treatment, and returned to the basal level between 12 h-24 h. Activation of adenylate cyclase with forskolin also decreased the GnRH-R mRNA levels. It is therefore concluded that in the granulosa cells of the small antral follicles GnRH-R mRNA expression was not homologously regulated by GnRH, while FSH may negatively regulate GnRH-R mRNA expression in the granulosa cells possibly through a cAMP-protein kinase A pathway.

GnRH and / or testosterone induced changes in reproductive activities during nonbreeding season in Calotes versicolor (Daud.).

Administration of Gonadotrophin releasing hormone (GnRH) to male C versicolor during nonbreeding season increases the weight of testis;diameter of testis, seminiferous tubule, Sertoli and Leydig cell nuclei. It also activates the spermatogenic process. Increase in the weight of epididymis and lowered cholesterol level of testis indicate androgen production. Treatment of tesotsterone along with GnRH further enhances the activities of testis as a few spermatozoa appeared in the lumen of seminiferous tubule along with increase in other spermatogenic elements. It may be concluded that the exogenous GnRH can induce reproductive activities during nonbreeding season when the environmental conditions are unfavourable. Testosterone administration has the additive effect on these activities.

Effect of naloxone on GnRH-induced LH and FSH release in buffalo, Bubalus bubalis.

The effect of naloxone on GnRH-induced LH and FSH release was measured in buffaloes in luteal phase of estrous cycle. Animals were administered intravenously, naloxone/saline (50 mg/injection) every 15 min for 3 hr followed by GnRH (100 micrograms). Peripheral plasma LH and FSH concentrations were measured in blood samples collected at 15 min intervals from 1 hr prior to beginning of naloxone/saline treatment up to 3 hr post GnRH administration and every 30 min for the subsequent 3.5 hr. Between the animals of Group I administered naloxone and those of Group II given saline, GnRH-induced peak LH and FSH concentrations, the total LH and FSH released in response to GnRH, and the time to peak LH and FSH concentrations were not significantly different. The results of the present study suggest the absence of a direct effect of naloxone on pituitary responsiveness to GnRH.

Synchronization of ovulation in crossbred dairy heifers using gonadotrophin-releasing hormone agonist, prostaglandin F2alpha and human chorionic gonadotrophin or estradiol benzoate

Girolando (Gir x Holstein) is a very common dairy breed in Brazil because it combines the rusticity of Gir (Bos indicus) with the high milk yield of Holstein (Bos taurus). The ovarian follicular dynamics and hormonal treatments for synchronization of ovulation and timed artificial insemination were studied in Girolando heifers. The injection of a gonadotrophin-releasing hormone (GnRH) agonist was followed 6 or 7 days (d) later by prostaglandin F2 alpha (PGF2alpha). Twenty-four hours after PGF2alpha injection either human chorionic gonadotropin (hCG, GPh-d6 and GPh-d7 groups) or estradiol benzoate (EB, GPE-d6 and GPE-d7 groups) was administered to synchronize ovulation and consequently allow timed artificial insemination (AI) 24 and 30 h after hCG and EB injection, respectively. Follicular dynamics in Girolando heifers was characterized by the predominance of three follicular waves (71.4 percent) with sizes of dominant follicles (10-13 mm) and corpus luteum (approximately 20 mm) similar to those for Bos indicus cattle. In the GnRH-PGF-hCG protocol, hCG administration induced earlier ovulation (67.4 h, P<0.01) compared to the control group (GnRH-PGF) and a better synchronization of ovulation, since most of it occurred within a period of 12 to 17 h. Pregnancy rate after timed AI was 42.8 (3/7, GPh-d6) to 50 percent (7/14, GPh-d7). In contrast, estradiol benzoate (GnRH-PGF-EB protocol) synchronized ovulation of only 5 of 11 heifers from the GPE-d7 group and of none (0/7) from the GPE-d6 group, which led to low pregnancy rates after timed AI (27.3 and 0 percent, respectively). However, since a small number of Girolando heifers was used to determine pregnancy rates in the present study, pregnancy rates should be confirmed with a larger number of animals

Post-Transcription Regulation of mRNA and Hormone Synthesis and Release at the Anterior Pituitary Gland: Information derived from the recovery of pituitary gonadotrope cell function after with a GnRH agonist

This review presents a summary of post-transcription regulation of mRNAs with a focus on the anterior pituitary gland. The control of gene transcription and production of mRNAs is the predominant form of regulation of hormone synthesis. However, post-transcription regulation of mRNAs provides another level of control of hormone synthesis. Examples of how hormone synthesis can be controlled at the level of mRNA include mRNA nuclear export and subcellular localization, mRNA stability and turnover, and regulation of mRNA translation. The gonadotrope cells of the anterior pituitary have multiple internal effector systems and provide an ideal model cell to study post-transcription regulation of mRNAs. Gonadotrope cells are stimulated to release LH and FSH by hypothalamic GnRH that binds to GnRH receptors. GnRH receptors are coupled to G-proteins and second messenger signaling pathways that involve cAMP and IP3. These signaling pathways are associated with the release of LH and FSH and transcription of mRNAs for LH and FSH. The stability of these mRNAs can be influenced by androgens, estrogens and progestagens. Therapy with a GnRH agonist leads to desensitization of gonadotrope cells to GnRH and a depletion of cellular stores of LH and FSH mRNAs, and content of LH and FSH. After discontinuation of therapy with GnRH agonist, levels of LH and FSH mRNAs return to normal some time before LH and FSH content and secretion are restored. This is indicative of post-transcription regulation of LH and FSH mRNAs. Future studies on post-transcription regulation of mRHAs will provide new molecular insights into how gonadotrope cells balance and integrate stimulation by GnRH with feedback modulation by the gonads.

Hormona liberadora de gonadotropinas (GnRH) y análogos en la inducción de la ovulación / Liberating Hormone of gonadotropinas (GnRh) and analogs in the induction of the ovulation

La utilización de GnRH como inductor de la ovulación en programas de F.I.V., se ha visto relegado a un segundo plano por la aplicación de gonadotropinas. Sin embargo, el uso de análogos de GnRH previa la estimulación ovárica con gonadotropinas, constituyen una práctica generalizada para la inducción de la ovulación en protocolos de FIV, por su capacidad para inhibir la actividad hipofisiaria y suprimir las concentraciones circulantes de las fracciones tanto inmunológica como biológicamente activas de la Hormona Luteinizante (LH)...

Effect of the dopamine antagonist, domperidone alone and in combination with thyroxine, clomiphene, hcg or gnRH on serum sex steroid profile, gonadal maturation and spawning of nile catfish, clarias lazera

The present investigation was carried out on one hundred and twenty mature Clarias lazera fish during the prespawning season [March - April]. Fish were allocated into two main groups [sixty fish of each sex] Fish weight ranged between 200-220 g. b. wt. Each main group was subdivided into six equal groups [Ten fish each], Fish of each group; both males and females were subjected to the same regimen of intraperitoneal exogenous treatment, as follows. 1[st] Group: Saline 0.65% NaCL solution. [Control] 2[nd] Group: Domperidone 5 microg/g. b. wt. in saline. 3[rd] Group: Domperidone 5 microg/g. b. wt, plus thyroxine 1 nancg / g. b. wt. in saline. 4[th] Group; Domperidone 5 microg/g, b. wt. plus clomiphene citrate l gamma g/g. b wt. in saline. 5[th] Group: Domperidone 5 micro g/g. b. wt. plus hCG 2 lU/g, b. wt. in saline. 6[th] Group: Domperidone 5 microg/g. b. wt. plus GnRH 10 microg/kg. b. wt. in saline. The present study revealed that [Domperidone] administration alone, in each sex of Clarias fish; increased serum sex steroid hormones [testosterone and 17 beta estradiol], gonadal weights [testes and ovaries], final gonadal maturation and gonadosomatic indices of both sexes as compared to respective controls. Exogenous administration of domperidone plus gonadotropin releasing hormone [GnRH] was the most effective treatment for production of sex hormones, final gonadal maturation and spawning in both sexes of Clarias lazera fish, followed by domperidone plus thyroxine; domperidone plus clomiphene citrate and domperidone plus hCG, respectively. In conclusion, the exogenous administration of dopamine antagonist plus GnRH is the most efficient regimen for enhancement of gonads maturation [gonadal recrudescence], spawning and spermiation of Clarias lazera fish throughout the prespawning season

Valor pronóstico de la respuesta inicial de los niveles séricos de estradiol al estímulo con análogos de GnRH en fertilización in vitro / Prognostic value of initial response of estradiol serum levels to stimulation with GnRH agonists in vitro fertilization

Se estudió el valor de la respuesta del estradiol (E2) al estímulo con análogo de (GnRH) en la fase folicular temprana. Estudio retrospectivo. Se estudiaron 403 ciclos de Fertilización in vitro (FIV) de enero de 1993 a diciembre de 1995. Se agruparon en 4 patrones dependiendo de la respuesta del estradiol al estimulo de a-GnRH en la fase folicular temprana. Patrón A (n=115). B (n=22). C (n=11) y D (n=3). Se incluyeron en el estudio aquellas pacientes manejadas en fase lútea corta, (FLC) (n=153) y larga (FLL) y larga (FLL) (n=97) como grupos controles. La prueba estadística que se utilizó fue análisis de varianza ANOVA con una P< 0.05 como estadísticamente significativa. La tasa de captura ovular fue mayor en los patrones A, B, FLC, y FLL con respecto al patrón D (p=0.001). La tasa de embarazo fue superior en A, B, y FLC y FLL (25 por ciento, 19 por ciento, 22 por ciento, y 25 por ciento) respectivamente (p=0.05). La edad se encontró mayor en C y D y fase lútea con un promedio de 35 ñ 2 (p=0.05). Los patrones que tuvieron una respuesta mejor, representada por el incremento de los niveles séricos de estradiol posterior al estímulo con a-GnRG, fueron A y B, ofreciendo un mejor pronóstico para el seguimiento en FIV

Lactation inhibits the potentiating effect of galanin upon the GnRH-induced LH release observed in diestrous-1 rat

Recent demonstrations of no changes in hypothalamic gonadotropin releasing hormone (GnRH) gene expression nd GnRH levels detected at the pituitary gland in diestrous and lactating rats, indicate that lactational hypogonadotropism in this species is not associated with inhibition of hypothalamic GnRH synthesis and secretion. Hypothalamic galanin potentiates GnRH effects on luteinizing hormone (LH) secretion in male and cycling rats. To explore the interaction between GnRH and galanin during lactation, we studied in vitro the effects of pulsatile stimulation with those peptides upon LH synthesis and secretion from rat pituitaries on diestrous 1 or day 10 of lactation. Hemipituitaries were separately incubated in 1 ml Dulbecco's Minimal Essential Medium supplemented with 1 per cent penicillin-streptomycin and fetal calf serum, at 37 degrees Celsius in 5 per cent CO2-air. The hemipituitaries were stimulated during 12 h with hourly pulses, 6 min each, of (a) gonadotropin releasing hormone (GnRH 25 ng/pulse), (b) rat galanin (600 ng/pulse), (c) GnRH plus galanin, or (d) saline. Medium was collected before each pulse to determine LH by radioimmunoassay. After the 12 h pulsatile regime total RNA was extracted and both actin and beta-LH mRNA were determined by reverse transcriptase polymerase chain reaction. There was a significant stimulation of LH secretion by GnRH (ANOVA, p<0.001) without significant differences between diestrous and lactation pituitaries. Galanin alone did not modify LH secretion but it potentiated the effect of GnRH upon pituitaries from diestrous (p=0.036) but not lactating rats. Neither peptide alone or its combination modified pituitary beta-LH mRNA levels. Results show that galanin regulates differently the secretion and synthesis of LH at the pituitary level. The disappearance of galanin-induced potentiation of GnRH effects upon LH secretion during lactation might contribute to the hypogonadotropism of lactation in the rat.

Devenir de embarazos expuestos inadvertidamente a análogos de GnRH durante programas de fertilización asistida / Background of inadvertently exposed pregnancies to GnRH analogs during assisted fertilization program

El embarazo precoz expuesto inadvertidamente a agonistas de GnRH constituye un cuadro clínico poco frecuente en la práctica ginecoobstétrica, su presentación corresponde a un 1 por ciento de los ciclos de pacientes tratadas por problemas de infertilidad mediante fertilización asistida. El objetivo de la presente comunicación es el relato de 4 casos de pacientes que participaron en el programa de fertilización asistida del Hospital Clínico San Borja Arriarán y que embarazaron en forma espontánea durante la fase lútea en la cual comenzó la desensibilización hipofisiaria con análogos de GnRH. De los casos observados, 2 presentaron un embarazo ectópico que fue corregido quirúrgicamente y dos cursaron con embarazos de evolución normal

Supresión farmacológica de la función ovárica y su utilidad clínica / Pharmacological suppression of ovarian function and its clinical use fulness

La hormona liberadora de gonadotropina (GhRH) es indispensable en la reproducción humana. Al modificar la estructura molecular de la hormona original, se han sintetizado análogos con efectos tanto agonistas como antagonistas. Los agonistas tienen una gran afinidad por los receptores y su uso contínuo o prolongado inhibe la liberación de FSH y LH. Por su parte, los antagonistas tienen un mecnaismo de acción completamente diferente, pero inhiben también la liberación de gonadotropinas. En la actualidad, el uso de análogos de Gn RH está indicado en padecimientos dependientes de hormonas y en otras condiciones clínicas

Regulacion de la luteinizacion folicular por un analago de la hormona liberada de gonadotrofinas (GnRH) / Regulation of follicular luteinization by an agonist of gonadotropin-releasing hormone (GnRH)

Tratamientos prolongados con análogos de GnRH son utilizados en la clínica con el objeto de suprimir la secreción endógena de gonadotrofinas, sin embargo estos análogos ejercen un efecto directo sobre el ovario. El objetivo de este trabajo fue estudiar la acción del análogo de GnRH acetato de leuprolide (LA) sobre esteroidogénesis y apoptosis ovárica. Se inyectó LA (1 Mug/rata/día) a ratas prepúberes superovuladas con PMSG/hCG. Se aislaron los cuerpo lúteos por microdisección y se incubaron durante 3 hs con LH (10 ng/ml) o dibutiril AMPc (dAMPc 1 mM). Se midió la progesterona producida observándose una disminución en el grupo LA tanto de la producción basal como en respuesta a LH (Basales = Control C: 96,6 + 9,6; LA: 22,9 + 2,8; LH= C: 145,7 + 4,9; LA: 23,6 + 2.0 ng/ml, p<0,001). En cambio el dAMPc estimuló significativamente en ambos casos (C: 153,9 + 11,8; LA:83,15 + 8,2). El AMPc producido fue menor en cuerpos lúteos del grupo LA y no fue estimulado por LH (Basales= C: 7,29 + 1,6; LA: 1,17 + 0,6; LH = C: 13,2 + 0,4; LA: 2,5 + 0,4 ng/ml, p<0,01). El contenido proteico por cuerpo lúteo fue semejante en los dos grupos. Por otro lado, teniendo en cuenta que en cortes histológicos de ovarios de ratas tratadas con LA encontramos mayor cantidad de folículos atrésicos y menor de cuerpos lúteos, hemos determinado la cantidad de células apoptóticas. Se tomó como criterio la presencia de cuerpos apoptóticos y núcleo en medialuna, detectándose un número mayor en el grupo LA. Este resultado fue confirmado por inmunohistoquímica (TUNEL). Se concluye que LA produce en el ovario una falla en el sistema receptor de LH- adenilato ciclasa y un aumento de la apoptosis celular.

The role of nitric oxide (NO) in control of hypothalamic-pituitary function

Neurons containing neural nitric oxide synthase (nNOS) are found in various locations in the hypothalamus and, in particular, in the paraventricular and supraoptic nuclei with axons which project to the median eminence and extend into the neural lobe where the highest concentrations of NOS are found in the rat. Furthermore, nNOS is also located in folliculostellate cells and LH gonadotropes in the anterior pituitary gland. To define the role of NO in the release of hypothalamic peptides and pituitary hormones, we inected an inhibitor of NOS, Ng- monomethyl-L-arginine (NMMA) or a releasor of NO, nitroprusside (NP) into the third ventricle (3V) of conscious castrate rats and determined the effect on the release of various pituitary hormones. In vitro, we incubated medial basal hypothalamic (MBH) fragments and studied inhibitors of NO synthase and also releasors of NO. The results indicate that NOergic neurons play an important role in stimulating the release of corticotrophin-releasing hormone (CRH), luteinizing hormone releasing-hormone (LHRH), prolactin-RH's, particularly oxytocin, growth hormone-RH (GHRH) and somatostatin, but not FSH-releasing factor from the hypothalamus. NO stimulates the release of LHRH, which induces sexual behavior, and causes release of LH from the pituitary gland. The intrahypothalamic pathway by which NO controls LHRH release is as follows: glutamergic neurons synapse with noradrenergic terminals in the MBH which release nonepinephrine (NE) that acts on alpha1 receptors on the NOergic neuron to increase intracellular free Ca++ which combines with calmodulin to activate NOS. The NOS diffuses to the LHRH terminal and activates guanylate cyclase (GC), cyclooxygenase and lipoxygenase causing release of LHRH via release of cyclic GMP, PGE2 and leukotrienes, respectively. Alcohol and cytokines can block LHRH release by blocking the activation of cyclooxygenase and lipoxygenase without interfering with the activation of GC. GABA also blocks the response of the LHRH neurons to NO and recent experiments indicate that granulocyte macrophage colony-stimulating factor (GMCSF) blocks the response of the LHRH neuron to NP by activation of GABA neurons since the blockase can be reversed by the competitive inhibitor of GABAa receptors, bicuculine.