Correlation Between Salivary, Platelet and Central Serotonin Levels in Children

Abstract

ABSTRACT:Background:Serotonin (5-HT) is a neurotransmitter synthesized in both the central nervous system (CNS) and in enterochromaffin cells of the gut. 5-HT biosynthesis is separate between the periphery and the CNS. Any observed correlations between centrally and peripherally measured 5-HT remain to be elucidated. Previous efforts have looked for a noninvasive marker of central serotonin, including serotonin in whole blood, plasma, platelets, saliva, and urine; however, results are conflicting.Aim:Finding a noninvasive marker for central serotonin turnover that can be used for diagnosis and therapeutic monitoring in patients with primary neurotransmitter deficiencies.Methods:Inclusion criterion was all children presenting with neurological symptoms whose clinical investigations included lumbar puncture (LP) for cerebrospinal fluid (CSF) collection and neurotransmitter metabolite analysis, were recruited. For central serotonin turnover, the serotonin metabolite 5-hydroxyindoleacetic acid (5HIAA) was used. Bivariate correlation between the serotonin levels in CSF (5HIAA), platelets, and saliva was calculated.Results:Twenty-six patients (aged 6 months to 15 years) with various neurologic presentations had LP for CSF collection and neurotransmitter metabolite analysis as part of their clinical care. An additional salivary and blood sample was obtained at the same time. Eighteen patients had suitable samples for quantitative measure of serotonin. There was no correlation between platelet serotonin and CSF 5HIAA levels (Pearson’s coefficient of correlation – PCC: 0.010) or between salivary serotonin and CSF 5HIAA (PCC: 0.258). There was a strong negative correlation between salivary and platelet serotonin (PCC: −0.679).Conclusion:Our findings suggest that salivary serotonin measurement is not a suitable noninvasive marker for measuring central serotonin turnover.

Decrease in Salivary Serotonin in Response to Probiotic Supplementation With Saccharomyces boulardii in Healthy Volunteers Under Psychological Stress: Secondary Analysis of a Randomized, Double-Blind, Placebo-Controlled Trial

“…This incompatibility may be partially explained by the fact that most applied psychometric tests covered a wide time frame, which may not be captured by a single time-point assessment of salivary 5-HT. Another explanation can be attributed to the site of origin of 5-HT in human saliva, which appears to be peripheral rather than CNS, as outlined in the majority of relevant studies ( 24 , 25 , 30 , 31 , 69 ). The only studies suggesting the level of 5-HT in saliva reflects its CNS status offer modest support: they either report a relatively low effect size ( 26 ) or examine diurnal fluctuations in salivary 5-HT ( 27 ).…”

“…In humans, among many biological fluids, 5-HT is also present in saliva (24)(25)(26)(27). It appears to derive from two 5-HT pools, one associated with the CNS and another with the periphery (28,29), both providing some contribution.…”

“…These suggest that salivary 5-HT is CNS-derived. On the other hand, 5-HT level in saliva was found to be only weakly and inconsistently correlated with its level in cerebrospinal fluid (CSF) in children presenting with neurological symptoms ( 24 ). In adult phenylketonuria patients, no association was found between the concentration of 5-HT in saliva and its turnover in the CNS ( 25 ).…”

Current methods for stress marker detection in saliva

“…In some papers, serotonin is considered as a stress biomarker, but mainly in blood or urine, where the concentration is higher [ 29 ]. Moreover, Egri et al found out that in children the salivary serotonin levels do not correlate well with plasma levels and Leung et al highlighted that they do not correlate with central serotonin turnover either, making serotonin a non-suitable salivary biomarker for evaluation of serotonergic system functioning [ 35 , 36 ].…”

50 Years Ago in T J P

“…Although it is true that serotonin has important implications for attention and memory, research has now shown that platelet and salivary levels of serotonin are not accurate reflections of central nervous system serotonin. 2 Stimulant medications were used for children with hyperactivity in the 1970s and remain the first line treatment. They are now thought to work by affecting synaptic levels of dopamine and norepinephrine in the prefrontal cortex, enhancing executive functioning.…”