RESUMO
Natriuretic peptides (NPs) are known to regulate reproductive events in polyovulatory species, but their function and regulation in monovulatory species remain to be fully characterized. Using a well-established in vivo model, we found that bovine granulosa cells from follicles near the deviation stage express mRNA for the three NP receptors (NPR1, NPR2 and NPR3), but not for NP precursors (NPPA, NPPB and NPPC). The abundance of NPR3 mRNA was higher in dominant compared to subordinate follicles at the expected time of follicular deviation. After deviation, mRNA for all NP receptors was significantly more abundant in the dominant follicle. Intrafollicular inhibition of oestrogen receptors downregulated NPR1 mRNA in dominant follicles. In granulosa cells from preovulatory follicles, NPPC mRNA increased at 3 and 6 h after systemic GnRH treatment, but decreased at 12 and 24 h to similar levels observed in samples collected at 0 h. After GnRH treatment, NPR1 mRNA was upregulated at 24 h, NPR3 mRNA gradually decreased after 3 h, while NPR2 mRNA was not regulated. The mRNA expression of the enzyme FURIN increased at 24 h after GnRH treatment. These findings revealed that the expression of mRNA encoding important components of the NP system is regulated in bovine granulosa cells during follicular deviation and in response to GnRH treatment, which suggests a role of NP system in the modulation of these processes in monovulatory species.
Assuntos
Bovinos/fisiologia , Peptídeos Natriuréticos/metabolismo , Folículo Ovariano/fisiologia , Animais , Feminino , Furina/genética , Furina/metabolismo , Regulação da Expressão Gênica , Hormônio Liberador de Gonadotropina/farmacologia , Células da Granulosa/metabolismo , Peptídeos Natriuréticos/genética , Ovulação/fisiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de EstrogênioRESUMO
Seven outbreaks of acute intoxication from oleander (Nerium oleander) in cattle were reported in Northeast of Brazil. A total of 92 cattle were poisoned by oleander in 7 different herds; 57 animals died (67% of affected cattle). All cases reported here occurred during dry season. Two of the outbreaks resulted from offering oleander triturated and mixed with fodder. In the other cases, accidental ingestion of residual parts of oleander derived from pruning or cutting plants on grazing land were responsible. Clinical signs were diverse; the most common were locomotion disturbances, diarrhoea, depression and sudden death. Postmortem findings varied from no significant lesions to widespread haemorrhage. The presence of oleander leaves in the rumen was noted in all cases. The lack of information about the toxicity of oleanders was the main cause for the accident, which prompt us to stimulate wide divulgation of the common toxic plants.