To assess alterations in H3R availability with age and body mass index (BMI) in healthy humans using in vivo[11C]GSK189254 positron emission tomography (PET) imaging.
Histamine is a neurotransmitter that plays a crucial role in regulating sleep/wakefulness, feeding, and memory processes. Histamine H3 receptors (H3R), a member of the histamine receptor family, are expressed in the cerebral cortex and striatum as well as in the peripheral nervous system. H3Rs regulate the synthesis and release of histamine as presynaptic autoreceptors and function as heteroreceptors to mediate the release of not only histamine butother neurotransmitters including acetylcholine, dopamine, noradrenaline and serotonin. Up to date, no in vivo human study has explored H3R availability with respect to age and BMI.
Twenty-four healthy individuals (2 females, 22 males; age range 20-47 years) were scanned with [11C]GSK189254 with High-Resolution Research Tomograph (HRRT) or HR plus scanner. Regional VT (volume of distribution) values were computed using the two-tissue compartment model.The correlation between VT and age, BMI were examined, adjusting for relevant potential confounding effects of age or gender and injected mass.
H3R availability (VT) was correlated with age but not BMI. VT displayed a negative correlation with age in the anterior cingulate cortex (r= -0.61, p= 0.004), frontal cortex (r= -0.50, p= 0.020), olfactory cortex (r= -0.50, p= 0.022), parietal cortex (r= -0.58, p= 0.006), cerebellum cortex (r= -0.53, p= 0.013), insula (r= -0.48, p= 0.027), putamen (r= -0.46, p= 0.034), thalamus (r= -0.45, p= 0.038), and hippocampus (r=0.45, p=0.039).
This in vivo H3R study found a significant age-related decline in most cortical and subcortical regions.