Research Round-up: Week 3

Shreya Kulkarni 12 February 2015

1) Depression is an increasingly common disease, affecting one in five adults in the UK today. However, its biological basis remains far from understood, although a role for the transmitter serotonin has been established. The nature of this involvement was also unclear until an international team of researchers based in America, Canada and here at the University of Cambridge published their findings this week. They claimed that the serotonergic system evolved to regulate energy levels in the brain. As a result, drugs which increase serotonin levels worsen the symptoms of depression in the short term due to disruption of energy regulation. A common example of such a drug is an SSRI (selective serotonin reuptake inhibitor). These SSRIs are known to have a therapeutic delay in terms of treatment. This delay can indeed be explained by the claim that symptom reduction is not achieved by direct effects from the SSRIs, but rather by the brain’s compensatory responses that attempt to restore energy regulation. These findings ultimately shed more light on the biological basis of depression and can lead to the development of more therapeutic targets for this increasingly prevalent disease in the future.

2) There has been overwhelming evidence to suggest that the world’s oceans are becoming increasingly acidic, but the impact on marine life has been less clear. Researchers, some from the University of Cambridge, have now found evidence to suggest that the population balance in these oceans may indeed be significantly altered. Certain types of marine organisms, collectively known as the ‘biofouling community’, grow in number, while other types can be reduced by up to 80%. Who wins and who loses may come down to the mere existence of a shell. Those with shells, such as tube worms, lose out while those without shells, such as sponges and sea squirts, double or even quadruple in number. After close examination, researchers found that the organic ‘glue’ holding the calcium carbonate crystals together was ‘eaten’ by the acid. As a result, the population balance of some marine ‘pests’ is drastically changed. What’s more, other organisms in the eco system may be impacted, as co-author Elizabeth Harper comments: “These environments are almost like mini-reefs, and if you lose some of that three-dimensional complexity, you reduce the space and opportunities for some types of marine life.”

3) Stress during pregnancy is common, but maternal stress can have an impact on the unborn baby. Some of the hormones involved in stress, namely ‘glucocorticoids’ are thought to regulate foetal and adult glucose metabolism. Dr Vaughan at the University of Cambridge investigated one particular glucocorticoid, known as corticosterone. The team found that administration of this hormone reduced the glucose supply to the baby. Dr Vaughan comments on the findings: “The foetuses of the mice with raised levels of the stress hormone tended to be smaller, despite the mother overeating, suggesting that a mother’s stress levels may affect her child’s growth.” They believe these effects are due to a modification in the activity of certain genes in the placenta, including the gene Redd1. Researchers believe that glucocorticoid levels may determine the specific combination of nutrients received by the foetus and influence the long term metabolic health of the child as a result. But there are ways to combat these potential problems, Professor Fowden, who led the research, adds: “It may be that by changing her diet, a mother can counter the effects of stress hormones on the human placenta.”