Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 170
Filtrar
1.
Ecol Evol ; 14(7): e11712, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39026958

RESUMO

Most work on plant competition intensity in general has focused on how aboveground and belowground competition for resources between plants changes with soil resource availability. In contrast, much work on the competitive effects of non-native invasive species on native species has focused on other mechanisms (e.g., allelopathy and microbial changes) and has largely ignored how these effects interact with mechanisms of resource competition along productivity gradients. We examined aboveground effects of an invasive grass, Microstegium vimineum, along with soil differences between invaded and non-invaded areas on two native perennial herbs at a productive and an unproductive oak woodland site in north Mississippi, USA. We transplanted 32 individuals each of Helianthus silphioides and Potentilla simplex from uninvaded areas into natural patches dominated by M. vimineum at each of the sites. Each transplant was randomly assigned to a pot with either native soil or soil from around M. vimineum roots. Aboveground competition was manipulated by securing M. vimineum shoots in a non-shading position around the transplant. We monitored survival of all transplants weekly in the growing seasons of 2020 and 2021. Transplant survival of H. silphioides was lowest in M. vimineum soil at the more productive site when M. vimineum was not pinned back. Transplant survival of P. simplex was lower at the more productive site but was mostly unresponsive to pinning and soil treatments. Synthesis. Our results suggest that soil-mediated legacy effects of an invader may reduce some native species' ability to compete for light at productive sites.

2.
Ann R Coll Surg Engl ; 104(1): 67-71, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34436956

RESUMO

INTRODUCTION: Audio-visual recordings made by patients of their clinical encounters are increasingly common. This may be done with or without their doctors' knowledge or consent and is considered admissible legal evidence. Many surgeons may feel uncomfortable with being recorded and lack knowledge regarding the legal implications. The aim of this study was to gauge how surgeons react to being recorded, and what specific medico-legal insight they have regarding these matters. METHODS: In total, 150 surveys were distributed to surgeons in two hospitals in South Wales by email, Survey Monkey and paper copy between 28 October 2019 and 9 March 2020. The survey was anonymous and recorded level of training, as well as four simple questions regarding how surgeons may react to being recorded and what they felt their legal rights were. RESULTS: There were 91 respondents: 28 consultants, 36 registrars and 27 junior surgical trainees. Of the respondents, 56% were uncomfortable with being recorded and 23% would stop a consultation if their patient insisted on recording it. These issues were most marked for junior surgical trainees. Sixty-two per cent of respondents were unaware of their legal rights and 21% believed they were legally able to refuse to continue a consultation. This belief was particularly marked among consultants. CONCLUSION: Many surgeons are uncomfortable with being recorded and lack knowledge regarding their medico-legal standing. Education and guidance from the Royal Colleges would help address this issue and avoid misunderstanding when surgeons are faced with these potentially difficult scenarios.


Assuntos
Atitude do Pessoal de Saúde , Encaminhamento e Consulta , Cirurgiões , Gravação em Vídeo , Humanos , Inquéritos e Questionários , País de Gales
5.
Domest Anim Endocrinol ; 74: 106514, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32693342

RESUMO

Embryonic mortality (EM) is a major factor limiting reproductive efficiency in cattle, and despite negative connotations related to reproductive performance, prostaglandin F2α (PGF2α) is capable of being released by the uterus by Day 30 of gestation. Therefore, the objective was to evaluate differences in PGF2α release after an oxytocin challenge between cows with high circulating concentrations of pregnancy-associated glycoproteins (PAGs) vs low PAG because of the association of increased PAG concentrations with pregnancy success. At Day 30 of gestation, pregnant cows were divided into oxytocin treatment (OT; n = 13) and control (CON; n = 12) groups. Treatment cows were further subdivided by circulating PAG concentration (high PAG, n = 7; and low PAG, n = 6). Blood samples were collected every 30 min beginning 1 h before oxytocin administration and continuing for 4 h. Prostaglandin F2α metabolite (PGFM), progesterone, estradiol-17ß (E2), and PAG concentrations were quantified. The peak concentration of PGFM occurred 2 h after oxytocin injection in treatment animals and returned to baseline levels by 4 h. No correlations were observed between PAG and PGFM, progesterone, or E2 concentrations (P > 0.05). There was no difference in initial or final PGFM concentrations between groups (P > 0.05). Progesterone and E2 concentrations decreased in cows after treatment of oxytocin (P < 0.05); however, only progesterone returned to basal concentrations by the end of the sampling period. In summary, cows with high vs low PAG concentrations at Day 30 of gestation have a similar PGFM response to oxytocin challenge.


Assuntos
Bovinos , Dinoprosta/metabolismo , Hormônios Esteroides Gonadais/sangue , Ocitocina/administração & dosagem , Resultado da Gravidez/veterinária , Proteínas da Gravidez/sangue , Animais , Perda do Embrião/veterinária , Estradiol/sangue , Feminino , Idade Gestacional , Gravidez , Progesterona/sangue
6.
Colorectal Dis ; 22(11): 1560-1567, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32506534

RESUMO

AIM: The involvement of pelvic sidewall (PSW) lymph nodes in rectal cancer is a marker of locally advanced disease and poor prognosis. Eastern countries generally advocate lateral lymph node dissection (LLND) over the Western approach of neoadjuvant chemoradiotherapy and more limited surgery. The aim of this study was to evaluate how these advanced cancers were treated in three UK Health Boards. METHODOLOGY: This was a retrospective review of three colorectal multidisciplinary team meetings from 2008 to 2016. All patients with rectal cancer and suspicious PSW lymph nodes on pretreatment MRI were included. RESULTS: There were 153 (6.2%) patients who met the inclusion criteria from a total of 2461 diagnosed rectal cancers. There was significant variability between the three centres with surgical intervention ranging from 59.2% to 84.4%, P = 0.015. There were 81 patients who had neoadjuvant chemoradiotherapy prior to surgery; of these 67 (82.7%) still had positive PSW nodes on the restaging MRI, but only 13 (19.4%) had LLND. There was no difference in local recurrence (15.3% vs 11.8%, P = 0.66), 5-year overall survival (69.2% vs 80.1%, P = 0.16) or 5-year disease-free survival (69.2% vs 79.4%, P = 0.72) between patients having LLND and those receiving standard neoadjuvant treatment followed by total mesorectal excision surgery. CONCLUSIONS: This study has demonstrated that rectal cancer patients with PSW positive nodal disease have advanced disease, mostly of the lower rectum, and receive a highly heterogeneous spectrum of therapies, even within a relatively small geographical area. Greater accuracy in our preoperative staging is needed to select those patients who will benefit from LLND surgery.


Assuntos
Recidiva Local de Neoplasia , Neoplasias Retais , Humanos , Incidência , Excisão de Linfonodo , Linfonodos/patologia , Metástase Linfática , Terapia Neoadjuvante , Recidiva Local de Neoplasia/epidemiologia , Recidiva Local de Neoplasia/patologia , Recidiva Local de Neoplasia/terapia , Estadiamento de Neoplasias , Neoplasias Retais/cirurgia , Estudos Retrospectivos
8.
Domest Anim Endocrinol ; 73: 106434, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32115309

RESUMO

Puberty is a complex biological event that requires maturation of the reproductive neuroendocrine axis and subsequent initiation of high-frequency, episodic release of GnRH and LH. Nutrition is a critical factor affecting the neuroendocrine control of puberty. Although nutrient restriction during juvenile development delays puberty, elevated rates of body weight gain during this period facilitate pubertal maturation by programming hypothalamic centers that underlie the pubertal process. Recent findings suggest that maternal nutrition during gestation can also modulate the development of the fetal neuroendocrine axis, thus influencing puberty and subsequent reproductive function. Among the several metabolic signals, leptin plays a critical role in conveying metabolic information to the brain and, consequently, controlling puberty. The effects of leptin on GnRH secretion are mediated via an upstream neuronal network because GnRH neurons do not express the leptin receptor. Two neuronal populations located in the arcuate nucleus that express the orexigenic peptide neuropeptide Y (NPY), and the anorexigenic peptide alpha melanocyte-stimulating hormone (αMSH), are key components of the neurocircuitry that conveys inhibitory (NPY) and excitatory (αMSH) inputs to GnRH neurons. In addition, neurons in the arcuate nucleus that coexpress kisspeptin, neurokinin B, and dynorphin (termed KNDy neurons) are also involved in the metabolic control of puberty. Our studies in the bovine female demonstrate that increased planes of nutrition during juvenile development lead to organizational and functional changes in hypothalamic pathways comprising NPY, proopiomelanocortin (POMC, the precursor of αMSH), and kisspeptin neurons. Changes include alterations in the abundance of NPY, POMC, and Kiss1 mRNA and in plasticity of the neuronal projections to GnRH neurons. Our studies also indicate that epigenetic mechanisms, such as modifications in the DNA methylation pattern, are involved in this process. Finally, our most recent data demonstrate that maternal nutrition during gestation can also induce morphological and functional changes in the hypothalamic NPY system in the heifer offspring that are likely to persist long after birth. These organizational changes occurring during fetal development have the potential to not only impact puberty but also influence reproductive performance throughout adulthood in the bovine female.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal , Bovinos/fisiologia , Sistemas Neurossecretores/crescimento & desenvolvimento , Estado Nutricional , Maturidade Sexual/fisiologia , Animais , Feminino , Sistemas Neurossecretores/efeitos dos fármacos , Gravidez , Fenômenos Fisiológicos da Nutrição Pré-Natal , Maturidade Sexual/efeitos dos fármacos
9.
Theriogenology ; 142: 229-235, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31629308

RESUMO

Objectives were to 1) characterize fixed-time AI (FTAI) pregnancy rates using the 5-Day CO-Synch + CIDR protocol in mature, suckled Bos indicus-influenced beef cows, 2) compare FTAI pregnancy rates in the latter to a modified version (5-Day Bee Synch + CIDR; Bee Synch I) that included treatment with prostaglandin F2α (PGF2α) at CIDR insertion on Day 0, and 3) test the hypothesis that elimination of both GnRH-1 at the onset of synchronization and the double dose of PGF on Day 5 (Bee Synch II) would not reduce FTAI pregnancy rates compared to Bee Synch I. For Experiment 1-trial 1, Brahman x Hereford (F-1) cows (n = 168) at least 40 d postpartum (PP; r = 40-92 d) at the time of CIDR insertion were administered the 5-Day CO-Synch + CIDR protocol with FTAI at 72 h after CIDR removal. Pregnancy rates to FTAI averaged 34.9 ± 1.9%. In Experiment 1-trial 2, fall- and spring-breeding Brahman x Hereford (F-1) beef cows (n = 269) were stratified by days PP and assigned randomly to receive either the 5-Day CO-Synch + CIDR (n = 136) or Bee Synch I (n = 133) protocol, with FTAI at 66 h after CIDR removal. Pregnancy rate to FTAI was greater (P < 0.05) in Bee Synch I (52.6 ± 0.9%) than in the 5-Day CO-Synch + CIDR procedure (40.4 ± 5.7%). For Experiment 2, 422 mature Braford, Brangus, Nelore x Brahman, and Brahman crossbred cows (Bos indicus proportion unknown) at 4 locations were treated with Bee Synch I, with FTAI at 66 h. Overall FTAI pregnancy rate averaged 51.7 ±â€¯2.1%. Finally, from 2013 through spring 2018, we used a switchback design using fall- and spring-breeding herds to compare Bee Synch I (402 observations) to Bee Synch II (393 observations). Overall frequency of detected estrus at 66 h using ESTROTECT™ breeding indicator patches was 57.2 ±â€¯2.4%, conception rates of those detected in estrus was 64.4 ±â€¯3.5%, and FTAI pregnancy rates averaged 52.3 ±â€¯2.4%, none of which differed between treatments. Moreover, pregnancy rates to FTAI in both treatments did not differ in cows synchronized between 40 and 80 d PP but increased after 80 d PP (P < 0.05). Bee Synch II, which eliminates GnRH-1 and the double dose of PGF2α on Day 5, results in FTAI pregnancy rates essentially identical to Bee Synch I but reduces synchronization costs and avoids the need for off-label (double dose PGF2α) drug use.


Assuntos
Bovinos , Dinoprosta/administração & dosagem , Sincronização do Estro/métodos , Fármacos para a Fertilidade Feminina/administração & dosagem , Inseminação Artificial/métodos , Indução da Ovulação/métodos , Prenhez , Administração Intravaginal , Animais , Esquema de Medicação , Combinação de Medicamentos , Detecção do Estro/métodos , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Injeções , Inseminação Artificial/veterinária , Indução da Ovulação/veterinária , Gravidez , Taxa de Gravidez , Resultado do Tratamento
10.
Anim Reprod Sci ; 204: 1-9, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30826249

RESUMO

A modification of the standard 5-day CO-Synch + CIDR procedure (5-day Bee Synch + CIDR; Bee Synch), developed for use in Bos indicus-influenced cows, utilizes the addition of prostaglandin F2α (PGF) on Day 0 of the protocol to eliminate mature corpora lutea (CL) and fixed-time AI (FTAI) at 66 h. Objectives were to test the hypothesis that elimination of GnRH on Day 0 (GnRH-1) does not impact significantly the synchronized development of a dominant follicle for presumptive FTAI. Seventy-one estrous cycling Brangus and Brahman x Hereford suckled cows were used in two replicates (35-36/replicate). Following stratification, cows were assigned randomly to a 2 × 3 factorial arrangement of treatments involving two truncated (no FTAI or GnRH-2) versions of Bee Synch (Bee Synch It and IIt), each begun 3, 7, and 10 days post-ovulation. Cows in Bee Synch It received 100 µg GnRH (GnRH-1), 25 mg PGF, and a CIDR on Day 0, whereas cows assigned to Bee Synch IIt received the same treatment but without GnRH-1. All cows received 50 mg PGF on Day 5 at CIDR removal. Synchronized new follicular wave emergence (NFWE; days 1-4) was observed in 68.6 and 38.9% of Bee Synch It and IIt, respectively (P = 0.01). This increased to 93.3% and 72.2%, respectively, if days 0-4 were considered. Inclusion of GnRH at CIDR insertion improved synchronized NFWE but size of the largest follicle at 66 h, the normal time of FTAI, did not differ due to treatment or day of the estrous cycle.


Assuntos
Bovinos , Corpo Lúteo/efeitos dos fármacos , Dinoprosta/farmacologia , Sincronização do Estro/métodos , Hormônio Liberador de Gonadotropina/farmacologia , Folículo Ovariano/efeitos dos fármacos , Administração Intravaginal , Animais , Preparações de Ação Retardada , Dinoprosta/administração & dosagem , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Inseminação Artificial/veterinária , Distribuição Aleatória
11.
Colorectal Dis ; 20 Suppl 8: 3-117, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30508274

RESUMO

AIM: There is a requirement of an expansive and up to date review of surgical management of inflammatory bowel disease (IBD) that can dovetail with the medical guidelines produced by the British Society of Gastroenterology. METHODS: Surgeons who are members of the ACPGBI with a recognised interest in IBD were invited to contribute various sections of the guidelines. They were directed to produce a procedure based document using literature searches that were systematic, comprehensible, transparent and reproducible. Levels of evidence were graded. An editorial board was convened to ensure consistency of style, presentation and quality. Each author was asked to provide a set of recommendations which were evidence based and unambiguous. These recommendations were submitted to the whole guideline group and scored. They were then refined and submitted to a second vote. Only those that achieved >80% consensus at level 5 (strongly agree) or level 4 (agree) after 2 votes were included in the guidelines. RESULTS: All aspects of surgical care for IBD have been included along with 157 recommendations for management. CONCLUSION: These guidelines provide an up to date and evidence based summary of the current surgical knowledge in the management of IBD and will serve as a useful practical text for clinicians performing this type of surgery.


Assuntos
Cirurgia Colorretal/normas , Gastroenterologia/normas , Doenças Inflamatórias Intestinais/cirurgia , Consenso , Humanos , Sociedades Médicas , Reino Unido
12.
Colorectal Dis ; 19(10): 881-887, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28872758

RESUMO

AIM: The incidence of Clostridium difficile infection (CDI) has been reported to be as high as 4% following ileostomy reversal. CDI can be associated with significant morbidity. A systematic review on this subject has not been previously reported; our aim was to review the literature to establish incidence and to evaluate the factors that may contribute to an increased risk of CDI following ileostomy reversal. METHOD: A systematic review of Ovid, Embase and Medline was undertaken. Search terms included C. difficile, reversal of ileostomy and ileostomy closure. Articles were included where at least one case of C. difficile-associated diarrhoea following reversal of defunctioning ileostomy was reported. Data extraction for articles was performed by two authors, using predefined data fields. The primary outcome measure was incidence of CDI amongst patients undergoing ileostomy reversal. Secondary outcomes were defunctioning time, antibiotic regime, acid suppression, time to onset of symptoms and study conclusions including colectomy and mortality rate. RESULTS: Eleven articles were included (five case reports and six cohort studies). The overall incidence of CDI was 1.8% (242/13 728). The mean defunctioning time was 8.7 months (range 6-12). A variety of antibiotic regimes were described. Mean time to onset of symptoms was 6 days (range 3-14). Use of acid suppression, colectomy or mortality rate were frequently not reported. CONCLUSION: CDI should be recognized as a potentially life-threatening complication of ileostomy closure. Careful consideration should be given to peri-operative antibiotic regime, acid suppression, timing of reversal and appropriate preoperative counselling of patients.


Assuntos
Clostridioides difficile , Enterocolite Pseudomembranosa/epidemiologia , Ileostomia/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Adulto , Idoso , Colectomia/estatística & dados numéricos , Enterocolite Pseudomembranosa/microbiologia , Enterocolite Pseudomembranosa/cirurgia , Feminino , Humanos , Ileostomia/métodos , Incidência , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/microbiologia , Complicações Pós-Operatórias/cirurgia , Fatores de Tempo
13.
J Anim Sci ; 95(5): 2080-2088, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28727020

RESUMO

Using a previously established model for nutritional acceleration of puberty, beef heifers ( = 48; 1/2 Angus × 1/4 Hereford × 1/4 Brahman) were used in a replicated 2 × 2 factorial design to examine the effects of diet type (high forage [HF] vs. high concentrate [HC]) and rate of BW gain (low gain [LG], 0.45 kg/d, vs. high gain [HG], 0.91 kg/d) on key metabolic hormones and age at puberty. After weaning at 14 ± 1 wk of age, heifers were assigned randomly to be fed HC-HG, HC-LG, HF-HG, or HF-LG ( = 12/group) beginning at 4 mo of age for 14 wk. Heifers were then switched to a common growth diet until puberty. Average daily gain was greater ( < 0.04) during the dietary treatment phase in HG heifers (0.81 ± 0.06 kg/d) than in LG heifers (0.43 ± 0.06 kg/d), and there was no diet type × rate of gain interaction. Puberty was achieved at a younger age (54.5 ± 1.8 wk) in both HG groups than in LG groups (60.2 ± 1.9 wk; < 0.04), but dietary energy source (HC vs. HF) did not influence this variable. Moreover, mean BW at puberty did not differ by diet type or rate of gain during the dietary treatment phase. Nonetheless, heifers fed HC-HG exhibited a striking increase ( < 0.0001) in serum leptin beginning at 26 ± 1 wk of age and remained elevated ( < 0.01) throughout the remainder of the experimental feeding phase compared to all other treatments. However, serum leptin in HC-HG dropped precipitously when heifers were switched to the common growth diet and did not differ from that of other groups thereafter. Overall mean concentrations of serum glucose were greater ( < 0.006) in HG heifers than in LG during the dietary treatment phase, with serum insulin also greater ( < 0.04) in HG than in LG only during weeks 20, 22, and 30. Mean serum IGF-1 was not affected by dietary type or rate of BW gain. We speculate that failure of the marked increase in serum leptin observed in HC-HG heifers during the dietary treatment phase to further accelerate puberty compared to HF-HG occurred because of its abrupt decline at the onset of the common growth phase, thus attenuating the temporal cue for activation of the reproductive neuroendocrine system.


Assuntos
Ração Animal/análise , Bovinos/fisiologia , Reprodução , Maturidade Sexual , Criação de Animais Domésticos , Fenômenos Fisiológicos da Nutrição Animal , Animais , Bovinos/crescimento & desenvolvimento , Dieta/veterinária , Metabolismo Energético , Feminino , Fator de Crescimento Insulin-Like I/análise , Leptina/sangue , Desmame , Aumento de Peso
16.
Ann R Coll Surg Engl ; 98(7): e138-40, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27269433

RESUMO

Introduction Malrotation of the midgut and appendiceal mucocoele are both extremely rare pathological conditions in adults. To our knowledge, there are only two reported cases in the English literature with a combination of both conditions. Case History A 65-year-old man presented with a 10-day history of upper abdominal pain associated with abdominal bloating and weight loss. He was otherwise fit and healthy with no significant past medical history. On examination, his abdomen was soft with tenderness and palpable fullness over the left upper quadrant. The initial blood test, chest x-ray and abdominal x-ray demonstrated no significant abnormality. Computed tomography showed a 17cm x 8cm x 6cm elongated cystic mass with possible malrotation of the intestines. Histopathology showed a low grade mucinous tumour of the appendix. At 12 months following surgery, there was no evidence of recurrence or postoperative complications and the patient was discharged from the care of the colorectal team. Conclusions We report a patient with a combination of two rare conditions. This case illustrates how a combination of pathologies can present a challenge to the unwary general surgeon.


Assuntos
Apêndice , Doenças do Ceco/complicações , Anormalidades do Sistema Digestório/complicações , Volvo Intestinal/complicações , Mucocele/complicações , Idoso , Apêndice/diagnóstico por imagem , Apêndice/patologia , Apêndice/cirurgia , Doenças do Ceco/diagnóstico por imagem , Doenças do Ceco/patologia , Doenças do Ceco/cirurgia , Anormalidades do Sistema Digestório/diagnóstico por imagem , Anormalidades do Sistema Digestório/patologia , Anormalidades do Sistema Digestório/cirurgia , Humanos , Volvo Intestinal/diagnóstico por imagem , Volvo Intestinal/patologia , Volvo Intestinal/cirurgia , Masculino , Mucocele/diagnóstico por imagem , Mucocele/patologia , Mucocele/cirurgia , Tomografia Computadorizada por Raios X
20.
J Neuroendocrinol ; 27(8): 647-57, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25944025

RESUMO

The timing of puberty and subsequent fertility in female mammals are dependent on the integration of metabolic signals by the hypothalamus. Pro-opiomelanocortin (POMC) neurones in the arcuate nucleus (ARC) comprise a critical metabolic-sensing pathway controlling the reproductive neuroendocrine axis. α-Melanocyte-stimulating hormone (αMSH), a product of the POMC gene, has excitatory effects on gonadotrophin-releasing hormone (GnRH) neurones and fibres containing αMSH project to GnRH and kisspeptin neurones. Because kisspeptin is a potent stimulator of GnRH release, αMSH may also stimulate GnRH secretion indirectly via kisspeptin neurones. In the present work, we report studies conducted in young female cattle (heifers) aiming to determine whether increased nutrient intake during the juvenile period (4-8 months of age), a strategy previously shown to advance puberty, alters POMC and KISS1 mRNA expression, as well as αMSH close contacts on GnRH and kisspeptin neurones. In Experiment 1, POMC mRNA expression, detected by in situ hybridisation, was greater (P < 0.05) in the ARC in heifers that gained 1 kg/day of body weight (high-gain, HG; n = 6) compared to heifers that gained 0.5 kg/day (low-gain, LG; n = 5). The number of KISS1-expressing cells in the middle ARC was reduced (P < 0.05) in HG compared to LG heifers. In Experiment 2, double-immunofluorescence showed limited αMSH-positive close contacts on GnRH neurones, and the magnitude of these inputs was not influenced by nutritional status. Conversely, a large number of kisspeptin-immunoreactive cells in the ARC were observed in close proximity to αMSH-containing varicosities. Furthermore, HG heifers (n = 5) exhibited a greater (P < 0.05) percentage of kisspeptin neurones in direct apposition to αMSH fibres and an increased (P < 0.05) number of αMSH close contacts per kisspeptin cell compared to LG heifers (n = 6). These results indicate that the POMC-kisspeptin pathway may be important in mediating the nutritional acceleration of puberty in heifers.


Assuntos
Núcleo Arqueado do Hipotálamo/citologia , Núcleo Arqueado do Hipotálamo/fisiologia , Neurônios/metabolismo , Estado Nutricional/fisiologia , Pró-Opiomelanocortina/fisiologia , Maturidade Sexual/fisiologia , Animais , Peso Corporal , Bovinos , Contagem de Células , Feminino , Hormônio Liberador de Gonadotropina/metabolismo , Hipotálamo/metabolismo , Kisspeptinas/biossíntese , Dados de Sequência Molecular , Neurônios/citologia , Área Pré-Óptica/metabolismo , Pró-Opiomelanocortina/biossíntese , alfa-MSH/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA