Conditions that affect sleep alter the expression of molecules associated with synaptic plasticity

Many theories propose that sleep serves a purpose in synaptic plasticity. W e tested the hypothesis, therefore, that manipulation of sleep would affect the expression of molecules known to be involved in synaptic plasticity. m RNA expression of four molecules [brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeleton-associated protein (Arc), matrix metallopr oteinase-9 (MMP-9), and tissue plasminogen activator (tPA)] was determined after 8 h of sleep deprivation and after 6 h of a mild increase in ambient temperature, a condition that enhances sleep in rats. After sleep deprivati on, BDNF, Are, and tPA mRNAs in the cerebral cortex increased while MMP-9 m RNA levels decreased. Conversely, after enhanced ambient temperature, BDNF, Arc, and tPA mRNAs decreased while MMP-9 mRNA increased. In the hippocampu s, sleep deprivation. did not significantly affect BDNF and tPA expression, although Arc mRNA increased and MMP-9 mRNA decreased. Brain temperature en hancement decreased Arc mRNA levels in the hippocampus but did not affect B DNF, MMP-9, or tPA in this area. Results are consistent with the notion tha t sleep plays a role in synaptic plasticity.