Groundbreaking research published today (June 16) sheds new light on how the foetal brain develops. It also suggests that smoking cannabis or taking a certain class of prescribed drugs while pregnant could harm the developing foetal brain.
This latest work significantly expands an earlier discovery demonstrating the importance of molecules produced naturally in our brains, that are similar in function to those found in cannabis, in the process of normal brain development.
These molecules called endocannabinoids function in a similar way to tetrahydrocannabinol (THC) from cannabis. It is THC that gives the high when cannabis is smoked.
Endocannabinoids and THC target the same receptors and signalling systems in the brain. Certain prescribed drugs, including some recently introduced to treat obesity, also act on these receptors.
The earlier study, conducted by many of the same scientists as the present study, identified the key role endocannabinoids play in regulating how certain nerve cells recognise and connect with each other.
This signalling process – which coincides with key steps in brain development and is extremely complex – should occur unhindered for our brain to develop normally.
New research published in the Proceedings of the National Academy of Sciences of the United States of America goes on to show that the influence of this crucial signalling system in the developing brain is much more widespread than was originally thought.
It also shows that many different nerve cells in our cerebrum – the part of the brain required for learning and memory - rely on this system to find their places and form their proper connections.
Jan Mulder, first author of the study and Alzheimer's Research Trust fellow at the University of Aberdeen's Institute of Medical Sciences, said: "Our initial findings showed the importance of these naturally occurring molecules in guiding the growth and connections of nerve cells in the developing brain. Now we demonstrate the extent of this signalling system and that complex networks of neurons – the backbones of higher cognitive functions – do not develop normally when endocannabinoid signalling is disturbed."
Professor Tibor Harkany, who was recruited to the University of Aberdeen as part of the Scottish Universities Life Sciences Alliance initiative to bolster cell biology research in Scotland, and a principal investigator of these studies added: "Our findings highlight that the integrity of this signalling system should be maintained and not disrupted if the brain is to develop normally. Anything that disrupts this process such as cannabis smoking or certain drugs that interfere with this signalling system could ultimately affect the brain's functionality."
Investigators at the University of Aberdeen collaborated on the paper Endocannabinoid actions during pyramidal cell specification and long-range axon patterning with colleagues at the Karolinska Institute, Sweden; Complutense University, Madrid, Spain; Baylor College of Medicine, Houston, TX, USA; National Institute for Medical Research, London; Johannes Gutenberg University Mainz, Germany; Institute of Biomolecular Chemistry, Pozzuoli, Italy; Mount Sinai School of Medicine, New York, NY, USA and ; and Linda and Jack Gill Center for Biomolecular Science and the Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN, USA for this study.