{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T01:52:03Z","timestamp":1787017923230,"version":"build-2736575974"},"reference-count":34,"publisher":"S. Karger AG","issue":"4","license":[{"start":{"date-parts":[[2018,1,1]],"date-time":"2018-01-01T00:00:00Z","timestamp":1514764800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2018,1,1]],"date-time":"2018-01-01T00:00:00Z","timestamp":1514764800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Neuroendocrinology"],"published-print":{"date-parts":[[2018]]},"abstract":"<b><i>Background:<\/i><\/b> Male testosterone levels decline by 1% per year from the age of 40 years. Whilst a primary testicular deficit occurs, hypothalamic or pituitary dysregulation may also coexist. This study aimed to compare the hypothalamic response to kisspeptin-54 and the pituitary response to gonadotropin-releasing hormone (GnRH) of older men with those of young men. <b><i>Methods:<\/i><\/b> Following 1 h of baseline sampling, healthy older men (<i>n<\/i> = 5, mean age 59.3 \u00b1 2.9 years) received a 3-h intravenous infusion of either vehicle, kisspeptin-54 0.1, 0.3, or 1.0 nmol\/kg\/h or GnRH 0.1 nmol\/kg\/h, on five different study days. Serum gonadotropins and total testosterone were measured every 10 min and compared to those of young men (<i>n<\/i> = 5\/group) (mean age 28.9 \u00b1 2.0 years) with a similar body mass index (24 kg\/m<sup>2<\/sup>) who underwent the same protocol. <b><i>Results:<\/i><\/b> Kisspeptin-54 and GnRH significantly stimulated serum gonadotropin release in older men compared to vehicle (<i>p<\/i> &#x3c; 0.001 for all groups). Gonadotropin response to kisspeptin-54 was at least preserved in older men when compared to young men. At the highest dose of kisspeptin-54 (1.0 nmol\/kg\/h), a significantly greater luteinising hormone (LH) (<i>p<\/i> = 0.003) response was observed in older men. The follicle-stimulating hormone (FSH) response to GnRH was increased in older men (<i>p<\/i> = 0.002), but the LH response was similar (<i>p<\/i> = 0.38). Serum testosterone rises following all doses of kisspeptin-54 (<i>p<\/i> \u2264 0.009) were reduced in older men. <b><i>Conclusions:<\/i><\/b> Our data suggest that healthy older men without late-onset hypo\u00adgonadism (LOH) have preserved hypothalamic response to kisspeptin-54 and pituitary response to GnRH, but impaired testicular response. Further work is required to investigate the use of kisspeptin-54 to identify hypothalamic deficits in men with LOH.<\/jats:p>","DOI":"10.1159\/000488452","type":"journal-article","created":{"date-parts":[[2018,3,15]],"date-time":"2018-03-15T18:01:18Z","timestamp":1521136878000},"page":"401-410","source":"Crossref","is-referenced-by-count":16,"title":["Hypothalamic Response to Kisspeptin-54 and Pituitary Response to Gonadotropin-Releasing Hormone Are Preserved in Healthy Older 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