My graduate school laboratory has become a public expert in the study of alcohol dependence within a chronobiological framework, but we have recently extended this expertise to another popular drug of abuse: cocaine (at least in the 80s but is still high-profile in the celebrity scence). Paper here. Using similar experimental techniques to that in our published ethanol studies, we found that cocaine, much like ethanol, acts to impair photic entrainment, particularly the ability of a light administered in the early night to delay activity rhythms
Cocaine, unlike ethanol treatment (at least in vivo), also enhances nonphotic (i.e anything but light) advances to rhythms, and acts at the level of the SCN in order to do so as we found out from directing infusing cocaine in the SCN. Our in vivo and in vitro studies confirmed that these cocaine-mediated circadian effects are largely mediated by alteration of serotonin signaling which, in general, is responsible for advancing circadian rhythms (nonphotically) and impairing photic entrainment through its antagonism with glutamate signaling. This confirmation was achieved by applying a serotonin antagonist (metergoline) either to the SCN slice in vitro or through a systemic injection of it in vivo and discovering the it blocks the ability of cocaine to advance rhythms. We are excited by these findings because it suggests that the disruption of circadian timing by drugs of abuse is drug- and pathway-specific in that the drugs may be acting through different neurotransmitter cascades (glutamate or serotonin) or brain pathways (through the SCN or outside of the SCN) to cause similar disruption of circadian timing.
Expect more cocaine-related papers in the future from the Glass lab, even if I am not in the opening credits. But, you’ll see some from this guy (third author of this paper, Adam Stowie) who recently took advantage of the fact that the head of the Glass lab (i.e. Dave Glass) is asking for trouble by leaving his convertible accessible for entry in the parking lot.
Glass, J., Brager, A., Stowie, A., & Prosser, R. (2012). Cocaine modulates pathways for photic and nonphotic entrainment of the mammalian SCN circadian clock AJP: Regulatory, Integrative and Comparative Physiology, 302 (6) DOI: 10.1152/ajpregu.00602.2011