Free access article

Reprod. Nutr. Dev. 46 (2006) 379-390
DOI: 10.1051/rnd:2006019

Dynamic and integrative aspects of the regulation of reproduction by metabolic status in male sheep

Dominique Blache, Song Zhang and Graeme B. Martin

School of Animal Biology M085, Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley 6009, Western Australia

(Published online 7 July 2006)

Abstract - Change in metabolic status, defined as a change in the availability of nutrients and energy to the tissues, is a powerful regulator of the reproductive function in small ruminants, especially in genotypes that are not strongly responsive to photoperiod such as the Merino sheep. In this paper, the dynamics of the response of the reproductive axis to changes in metabolic status are reviewed in the light of recent studies. The nature and the roles of the various components of the pathways linking metabolic status to reproduction are considered: nutrients and metabolites, the endocrine system, and the nervous system. We discuss the role of leptin and insulin in detail because of the central role of these two hormones in both the early gonadotrophin response to increase in nutrition and the long-term response of the testis to dietary stimulation. The possible roles of recently identified peptides, such as ghrelin and kisspeptin, are also considered as we develop a general hypothesis that encompasses the different levels of integration necessary to explain the complex interactions between reproductive function and metabolic status, and the possible existence of a "metabolic memory" in this interaction.

Key words: nutrition / GnRH / LH / leptin / insulin / testis

Corresponding author: dbla@animals.uwa.edu.au

© INRA, EDP Sciences 2006

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