41 research outputs found
The effect of an intracerebroventricular injection of metformin or AICAR on the plasma concentrations of melatonin in the ewe: potential involvement of AMPK?
<p>Abstract</p> <p>Background</p> <p>It is now widely accepted that AMP-activated protein kinase (AMPK) is a critical regulator of energy homeostasis. Recently, it has been shown to regulate circadian clocks. In seasonal breeding species such as sheep, the circadian clock controls the secretion of an endogenous rhythm of melatonin and, as a consequence, is probably involved in the generation of seasonal rhythms of reproduction. Considering this, we identified the presence of the subunits of AMPK in different hypothalamic nuclei involved in the pre- and post-pineal pathways that control seasonality of reproduction in the ewe and we investigated if the intracerebroventricular (i.c.v.) injection of two activators of AMPK, metformin and AICAR, affected the circadian rhythm of melatonin in ewes that were housed in constant darkness. In parallel the secretion of insulin was monitored as a peripheral metabolic marker. We also investigated the effects of i.c.v. AICAR on the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC), a downstream target of AMPK, in brain structures along the photoneuroendocrine pathway to the pineal gland.</p> <p>Results</p> <p>All the subunits of AMPK that we studied were identified in all brain areas that were dissected but with some differences in their level of expression among structures. Metformin and AICAR both reduced (p < 0.001 and p < 0.01 respectively) the amplitude of the circadian rhythm of melatonin secretion independently of insulin secretion. The i.c.v. injection of AICAR only tended (p = 0.1) to increase the levels of phosphorylated AMPK in the paraventricular nucleus but significantly increased the levels of phosphorylated ACC in the paraventricular nucleus (p < 0.001) and in the pineal gland (p < 0.05).</p> <p>Conclusions</p> <p>Taken together, these results suggest a potential role for AMPK on the secretion of melatonin probably acting trough the paraventricular nucleus and/or directly in the pineal gland. We conclude that AMPK may act as a metabolic cue to modulate the rhythm of melatonin secretion.</p
Interactions entre facteurs photopériodique et nutritionnel sur les profils saisonniers de reproduction des ovins
The interaction between photoperiod and nutrition and its effects on the seasonal pattern of reproduction in the ewe
LâĂ©tude des effets de la nutrition sur les profils saisonniers de reproduction ainsi que sur les techniques naturelles visant Ă maĂźtriser ce caractĂšre, prĂ©sente un intĂ©rĂȘt tout particulier pour le dĂ©veloppement de systĂšmes dâĂ©levage ovins durables. Nos travaux dĂ©montrent que lâĂ©tat dâengraissement est un facteur capable dâinteragir avec la photopĂ©riode pour moduler le moment des transitions saisonniĂšres reproductives. Cet effet nâaffecte pas la synchronisation annuelle du rythme reproductif des brebis et sâeffectue indĂ©pendamment de leur degrĂ© de saisonnalitĂ©. Les effets de lâĂ©tat dâengraissement se transmettent, en partie via la voie AMPK, sur lâamplitude du rythme journalier et endogĂšne de sĂ©crĂ©tion de mĂ©latonine chez la brebis Ăle-de-France, sans quâune implication fonctionnelle de ce phĂ©nomĂšne puisse ĂȘtre dĂ©terminĂ©e. Enfin, lâĂ©tat dâengraissement contribue de façon significative Ă la variabilitĂ© de la rĂ©ponse des brebis Ă un traitement dâimplants de mĂ©latonine ainsi quâĂ la rĂ©alisation dâun effet mĂąle, tous deux rĂ©alisĂ©s en fin de saison dâanoestrus chez la brebis Ăle-de-France.To determine the effect of nutrition on the seasonal patterns of reproduction and on the natural techniques used to control these patterns, is a feature of particular interest in the development of sustainable sheep breeding systems. This work establishes that body condition is a potent factor that interacts with photoperiod to modulate the timing of seasonal reproductive transitions in sheep. This effect does not result in an alteration in the synchronization of the annual reproductive rhythm and is independent of the degree of seasonality of the breed of sheep considered. The effect of body condition involves the AMPK system to alter the amplitude of the daily and endogenous rhythm of secretion of melatonin in the Ile-de-France breed of sheep; a functional implication for this phenomenon remains to be determined. Finally, body condition contributed significantly to the variability of the response of sheep to a treatment with melatonin implants and to the male effect, both performed at the end of the anestrus season for the Ile-de-France breed
Bien-ĂȘtre animal. Chap VIII
Public visé : Enseignants et formateurs de l'enseignement agricoleNational audienc
Bien-ĂȘtre animal. Chap VIII
Public visé : Enseignants et formateurs de l'enseignement agricoleNational audienc
Les facteurs photopériodique et nutritionnel interagissent sur les transitions saisonniÚres de reproduction chez les ovins
National audienc
How can precision livestock farming contribute to the principles of agroecology?
International audienceLivestock farming systems are facing major currents of transitions with growing consideration for agroecology, âOne Health and One Welfareâ concepts, and increasing integration of digital technologies and sciences. Precision livestock farming technologies can contribute to the pillars of agroecology, for instance through precision feeding to reduce the inputs required for production; sensors and automata can also help to adopt management practices to improve global health and welfare of animals and farmers. Furthermore, digital technologies can help maintain or promote agroecological livestock farming systems through solutions that monitor animals, and facilitate the management and traceability of practices in more extensive systems, such as mountain farming or pastoralism. Therefore, new technologies have the potential to support agroecological transitions, but will not be the driving force behind these transitions. Possible negative externalities, such as environmental impact of digital technologies must also be weighed against their positive internalities for a successful and sustainable integration of digital tools into agroecological livestock farming systems
Los ritmos estacionales de la actividad reproductiva en ovinos y caprinos son controlados por el fotoperiod pero modulados por el efecto macho y la nutricion
International audienc
Nutrition affects natural or induced seasonal reproductive transitions in the ewe
International audienc
Central structures involved in the endocrine response to the first contact with the sexual partner or its odor in young and sexually naive anoestrus ewes: An immunohistochemistry study
National audienc