Browsing by Author "Paiva, Luis"
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- ItemAdministration of Beta-Nerve Growth Factor during the Preovulatory Stage Improves Endocrine and Luteal Function in Dairy Heifers(MDPI, 2023) Gajardo, Gonzalo; Paiva, Luis; Ulloa-Leal, Cesar; Valderrama, Ximena; Lopez, Gerardo; Carrasco, Albert; Hidalgo, Alejandra Isabel; Silva, Mauricio E.; Palma, Patricio I.; Ratto, Marcelo H.Simple Summary Certain proteins present in semen regulate the reproductive physiology of females. Beta-nerve growth factor (NGF), which is abundantly expressed in the semen of camelids, has a potent ovulatory and luteotrophic effect in llamas after systemic injection. Here, we investigated the effects of intramuscular NGF during the preovulatory stage on endocrine parameters and pregnancy rates after artificial insemination in dairy heifers. Heifers injected with NGF showed enhancement of hormones related to ovulation and gestation maintenance. We also detected the enhancement of genes related to uterine receptivity and higher pregnancy rates. We conclude that the improvement in reproductive hormones related to gestation is possibly linked to the higher pregnancy rate detected here. More research is needed to ensure the NGF effects remain on commercial exploitation farms. The neurotrophin beta-nerve growth factor (NGF), which is present in the semen of different mammals, elicits potent ovulatory and luteotrophic actions in llamas following systemic administration. Here, we determine if purified NGF given intramuscularly (IM) during the preovulatory stage affects the corpus luteum (CL), hormone production, endometrial gene expression, and pregnancy rate of dairy heifers. Holstein-Friesian heifers were estrus-synchronized using estradiol benzoate (EB) plus an intravaginal progesterone (P4) device (DIB). After eight days, the device was removed and cloprostenol was given IM; the next day (day 9), heifers received EB IM plus one of the following: (i) 1 mg of NGF (NGF D9 group), (ii) 1 mg of NGF 32 h after EB (NGF D10 group), or (iii) phosphate buffer saline (control group). To measure pregnancy rates, heifers were treated similarly, then artificially inseminated with sexed semen 48-52 h after DIB removal, then an ultrasound was conducted 30 days after insemination. The females given NGF along with EB (NGF D9) showed significantly higher luteinizing hormone (LH) concentrations, larger CL vascular areas, and higher plasma P4 concentrations than the NGF D10 and control animals. Downregulation of the P4 receptor (PGR), and upregulation of both lipoprotein lipase (LPL) and Solute Carrier Family 6 member 14 (SLC6A14) endometrial genes, were detected in NGF D9 heifers. Furthermore, these heifers had a 10% higher pregnancy rate than the control group. We conclude that the higher P4 output, in response to the early NGF administration, led to the enhanced gene expression of transcripts related to uterine receptivity that may result in enhanced pregnancy rates.
- ItemSeminal plasma nerve growth factor signaling on the reproductive physiology of female llamas(BRAZILIAN COLL ANIMAL REPRODUCTION, 2022) Paiva, Luis; Silva, Mauricio; Carrasco, Rodrigo; Ratto, Vicente; Goicochea, Jose; Ratto, MarceloThe ovulation mechanism is one of the fascinating physiological processes in reproductive biology in mammals. From the reproductive point of view, the species have been classified as spontaneous or induced ovulators. Although the release of GnRH followed by the preovulatory LH surge is shared between both types of ovulation, the stimulus to initiate GnRH release varies between both categories. In spontaneous ovulators, ovulation depends on the systemic concentration of ovarian steroids, however, in induced ovulators, different stimuli such as copulation, environmental, and social cues can facilitate or induce ovulation regardless of the increases in systemic estradiol concentration. In this review, we document evidence that a male-derived protein is the main factor responsible for inducing ovulation and also modulating the ovarian function in the domestic South American camelid, the llama. The neurotrophin beta-Nerve Growth Factor (beta-NGF) is the principal factor present in the semen of llamas responsible for inducing ovulation in this species. After the intrauterine deposit of semen during mating, beta-NGF is absorbed through the endometrium to reach the circulatory system, where it reaches the hypothalamus and stimulates GnRH release. The potential site of action of this neurotrophin at the brain has not been elucidated, however, hypotheses are raised that the factor may cross the blood-brain barrier and stimulate upstream neuronal networks that lead to the stimulation of GnRH-secreting neurons. It is possible that beta-NGF could be sensed at the median eminence without crossing the blood-brain barrier. Finally, it has been observed that this factor is not only a powerful stimulator of ovulation but also has a luteotrophic effect, resulting in the development of a corpus luteum capable of secreting more progesterone when compared to other ovulation-stimulating analogues.
- ItemThe ovulatory and luteotropic actions of the male-derived beta-nerve growth factor in South American camelids(OXFORD UNIV PRESS INC, 2022) Paiva, Luis; Silva, Mauricio; Carrasco, Rodrigo; Hector Ratto, Marcelo