Abstract
Major urinary proteins (Mups) are important for rodent scent communication and sexual behaviour. Recent evidence suggests that Mup1 may be regulated by fasting and re-feeding (RF). However, other Mup isoforms are poorly investigated, and data on the impact of long-term dietary restriction (DR) and ad libitum RF on Mup expression are missing. We investigated the effects of long-term 25 per cent DR and subsequent RF on Mup expression in male C57BL6 mice. DR significantly decreased Mup gene expression, hepatic and urinary protein levels compared with ad libitum (AL) fed control mice, with the greatest downregulation found for Mup5 expression. The decline in Mup expression was inverted by six months of RF. Because of inhibitory glucocorticoid response elements in the genomic sequence of the Mup5 gene, the observed inverse correlation of nuclear glucocorticoid receptor levels with Mup expression in response to DR and subsequent RF is a possible regulatory mechanism. Additionally, gene-expression-inhibiting histone deacetylation (H3K9) occurred in the region of the Mup5 gene in response to DR. We assume that Mup may act as a molecular switch linking nutritional status to sexual behaviour of mice, and thereby regulating male fertility and reproduction in response to food supply.