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  • The International Journal of Neuropsychopharmacology, Volume 10, Issue 2
  • April 2007, pp. 219-229

Gender and age affect NK1 receptors in the human brain – a positron emission tomography study with [18F]SPA-RQ

  • Mikko J. Nyman (a1), Olli Eskola (a2), Jaana Kajander (a1), Tero Vahlberg (a3), Sandra Sanabria (a4), Donald Burns (a4), Richard Hargreaves (a4), Olof Solin (a2) and Jarmo Hietala (a1) (a5)
  • DOI:
  • Published online: 01 March 2006

Substance P (SP) is a neurotransmitter and neuromodulator that mediates its effects in the brain predominantly via the neurokinin-1 receptors (NK1Rs). NK1Rs and SP have been shown clinically to be involved in nausea and emesis after chemotherapy (CINV) and have been implicated preclinically in a range of neuropsychiatric disorders but unlike CINV their blockade in these conditions does not have proven clinical value. We investigated whether age and gender affects NK1R binding potential (NK1R-BP; an index of receptor availability) in the living human brain using PET and [18F]SPA-RQ, a highly specific NK1R antagonist. Forty-five healthy volunteers (35 male and 10 female), aged between 19 and 55 years were studied. NK1R-BP was estimated using the simplified reference tissue model with cerebellum as a reference region. A regression analysis indicated that that a loss of NK1R is associated with normal ageing as shown by decreased NK1R-BP (average rate 7% per decade). Statistically significant negative associations between age and NK1R-BP were observed in temporal, parietal and frontal cortex, hippocampus and parahippocampal formation. In addition preliminary data were obtained suggesting possible gender differences in NK1R-BP in the cortex and putamen with females having a lower NK1R-BP. The exact physiological significance of these results remains to be elucidated but conceptually they could be involved in age-related CNS disorders or those with gender differences in prevalence.

Corresponding author
Professor of Psychiatry, Department of Psychiatry, University of Turku, Kunnallissairaalantie 20, Building 9, 20700-Turku, Finland. Tel.: +358-2-269 2520 Fax: +358-2-269 2528 E-mail:
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The International Journal of Neuropsychopharmacology
  • ISSN: 1461-1457
  • EISSN: 1469-5111
  • URL: /core/journals/the-international-journal-of-neuropsychopharmacology
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