Antagonists – what do they do?

dementia-3761172_640Antagonists are any chemicals that fit into receptor sites on the post-synaptic neuron, inhibiting the neuron from firing. Well-known antagonists for serotonin, which we looked at in the previous blog post, are anti-psychotic drugs like Clozapine, which acts on the HT2A serotonin receptors to decrease the effects of serotonin in the brain. Many ant-psychotic drugs also act as antagonists for dopamine, as an excess of both dopamine and serotonin has been associated with schizophrenia.

However, easy-to-understand studies referencing this effect of Clozapine are difficult to come by, so while this is useful knowledge for students on how anti-psychotic medication works, when teaching about antagonists there is more available research on the effects of scopolamine on acetylcholine, and hence on memory.  (And incidentally on motion sickness, as scopolamine is excellent at preventing nausea and vomiting!)

Scopolamine acts by blocking the acetylcholine receptors, specifically the muscarinic receptors (see the link below). Atri et al (2004)  reported how blocking the muscarinic acetylcholine receptors (mAChRs), by injecting scopolamine impairs learning of paired words.

As an age-related deterioration in cognitive function is thought to be predominantly related to a decline in cholinergic neurotransmission (relating to nerve cells in which acetylcholine acts as a neurotransmitter), scopolamine administration has often been used to model dementia. Scopolamine has therefore been extensively used for preclinical and clinical testing of treatments for cognitive impairment.  For example, Tröster et al (2013) found that scopolamine negatively affected anterograde short-term memory and verbal and nonverbal learning in middle-aged men.

Later School Start Times Help Students

asleep-3126444_640It has long been suspected, and now research is supplying the evidence: delaying school start times results in students getting more sleep, and feeling better.  The most recent study in Singapore investigated the impact of a 45-min delay in school start time on sleep and well-being of adolescents.  They shifted the start of the school day from 7.30am (which though early is not uncommon in Asian countries) to 8.15am, without making the day end later.  After one month, researchers interviewed students and found that bedtimes on school nights were delayed by nine minutes while the times students got up were delayed by about 32 minutes, resulting in an increased time in bed of 23 minutes.  This may not seem like much, but the percentage of students getting at least 8 hours of sleep in the school week rose from 6.9% to 16%, and all reported more alertness and feelings of well-being.

These findings support studies from the USA and UK.  However, it has proved difficult to change practices, even in face of this evidence, and calls in 2015 by Paul Kelley of the Sleep and Circadian Neuroscience Institute at the University of Oxford, to delay the start of school and college in the UK for the benefit of students largely went unheard or unheeded.  Teenagers don’t get to make educational policy!