Literature Review | September 2017

Select a topic from the list below:

• High serum serotonin in sudden infant death syndrome (SIDS)
   
• Proteomic evaluation of mouse adipose tissue and liver following hydroxytyrosol supplementation

High serum serotonin in sudden infant death syndrome (SIDS)
Robin L. Haynes, Andrew L. Frelinger III, Emma K. Giles, Richard D. Goldstein, Hoa Tran, Harry P. Kozakewich, Elisabeth A. Haas, Anja J. Gerrits, Othon J. Mena, Felicia L. Trachtenberg, David S. Paterson, Gerard T. Berry, Khosrow Adeli, Hannah C. Kinney, and Alan D. Michelson, PNAS, 2017, 114, 7695–7700.

A better understanding of the conditions causing a nightmare for mothers with new-born babies has come to light with the work of Haynes RL et al, who demonstrated that sudden infant death syndrome (SIDS) is associated with peripheral abnormalities of serotonin (5-hydroxyltryptamine, 5-HT) pathway. Their premise has been that the sudden infant death syndrome, SDIS is likely due to the heterogeneous group of disorders and presumably relates to three factors inflicted upon infants simultaneously: i, an underlying vulnerability of infant; ii, critical developmental stage of infant, and iii, exogenous stressor such as asphyxia secondary to sleeping in prone or face-down position. Authors found in their first study that subset of SIDS have abnormalities in 5-HT in caudal brainstem that plays major role in homeostatic regulation of hypercarbia and hypoxia during sleep: in 40% of SIDS a decreased 5-HT and its key biosynthetic enzyme tryptophan hydroxylase was found as well as aberrations in 5-HT_1A receptor binding and 5-HT cell density.  90% of 5-HT is produced peripherally in the gastrointestinal tract and other organs. 95% of 5-HT in blood is carried in dense granules within platelets.  In this comprehensive study authors report that 1/3 of SIDS cases have much larger levels of 5-HT in plasma, being 2 standard deviations above the mean value of controls. The positon at sleep (such as face-down or prone), and breastfeeding or not had no influence on the levels of 5-HT. The reason behind the increase in 5-HT is still unknown. 90% of 5-HT is produced in gut enterochromaffin cells; the production is increased under hypoxia and infection. Neuroendocrine cells and neuroepithelial cells of lung function as airway oxygen/carbon dioxide sensors and release 5-HT upon hypoxia. Hyperplasia and hypertrophy within lungs of SIDS infants have been demonstrated. Due to the inherent difficulty in directly evaluating brain function in vivo and similarity between the platelets and central neurons, the high serum 5-HT may be eventually proven as a good peripheral biomarker of central 5-HT abnormalities. Haynes said that the SIDS infants may be “better identified as having serotonopathy” rather than SIDS”. (Prepared by Ines Batinic-Haberle, Duke University School of Medicine)

Proteomic evaluation of mouse adipose tissue and liver following hydroxytyrosol supplementation
João Tomé-Carneiroa, M. Carmen Crespoa, Estefanía García-Calvob, José L. Luque-Garcíab, Alberto Dávalosc, Francesco Visioli. Food and Chemical Toxicology, Volume 107, Part A, September 2017, Pages 329-338.

Hydroxytyrosol (HT) is a phenolic compound (specifically, a phenylethanoid) which is found in the fruits and leaves of the olive tree (Olea europaea L.). Thus, the compound present in the food products derived from this plant, especially in olive oil. The bioactive properties of HT came into attention following the observation of the beneficial effects of the Mediterranean diet against cardiovascular disease, in particular, its inclusion of copious amounts of olive oil. Currently, HT is one of several olive oil polyphenols which is mentioned by the scientific committee of the European Food Safety Authority (EFSA), as being under preliminary research for the potential to affect blood lipid levels. HT has also being claimed to possess antioxidant potential and cytoprotective effects through in vitro studies, and has been identified to be the strongest in vitro antioxidant out of all the olive oil polyphenols. In view of these positives surrounding HT, the study by Tomé-Carneiroa et al aimed at determining the impact of long-term HT supplementation on the proteome of adipose and liver tissue in C57BL/6J mice. In this investigation, the animals received either a controlled diet or a diet supplemented with representative doses of HT for eight weeks. Super-stable isotope labeling with amino acids in cell culture (super-SILAC) was used for assessing the effects of HT in the adipose and liver tissues; the compound was observed to have a differential effect in these two tissues, in this instance. It was also observed that some oxidative stress-related proteins such peroxiredoxin 1 were modulated in both these two tissues, where they were observed to be consistently repressed by HT supplementation. Tissue-dependent modulation was also observed in the animals supplemented with HT, as in the case of fatty acid synthase (FASN). In conclusion, the researchers of this study demonstrated that HT was an ideal candidate for modulating physiological levels of blood lipids. It was also demonstrated that the usage of proteomics was a useful methodology for elucidating novel potential pharmaco-nutritional targets for HT supplementation. By using these techniques, the authors were able to see the metabolic effects of HT supplementation at the proteomics tissue level.ng to Nox1, may prove an additional beneficial target for PAH treatment. (Prepared by Viduranga Waisundara, Technology Degree Programme (Food Technology), Faculty of Applied Sciences, Rajarata University of Sri Lanka, Mihintale, Sri Lanka)