This is a summary of a presentation in Symposium 222. Molecular Basis of Addiction: Neurocognitive Deficits and Memory Mon, Apr 28, 9:55 AM – 12:10 PM at the 2014 Experimental Biology meeting.
Mon, Apr 28, 10:25 – 10:40 AM Amphetamine exposure during development causes epigenetic trans-generational changes in drug sensitivity in Caenorhabditis elegant. Authors: Talus McCowan, Bryan Safratowich, Joyce Ohm, Lucia Carvelli
McCowen* presented a study which showed transgenerational effects of amphetamine in a C. elegans model.
Caenorhabditis elegans is a nematode about 1 mm long which has the dubious virtue of having 302 neurons of which a mere 8 are dopaminergic. This makes for a tractable model, particularly when you think you might want to model the entire nervous system.
The model involved Swimming Induced Paralysis (SWIP) which can be induced in a liquid medium by treating the worm with amphetamine. This is a time and dose dependent phenomenon which has been shown to depend on the dopamine transporter and D2/3-like dopamine receptors. Classic targets of the amphetamines.
The study exposed eggs to 500 uM amphetamine or control media for 15 hours. After maturation of the worms, they were subjected to the SWIP test in which it was found that the egg-exposed animals had an enhanced freezing response. In this case it was an increased percentage of the worms freezing in the context of a moderate dose, selected to give parametric range on either side. The authors then examined the F1 generation of worms, which had received no drug treatment up until the SWIP challenge. here it was found that the F1 offspring of the F0 worms exposed to amphetamine during development also had an enhanced response to amphetamine.
The lab is interested in methylation of histones as an epigenetic mechanism that might possibly convey this effect. They found decreases of histone H3 Lys4 trimethylation (H3K4me3) in the F1 offspring of amphetamine incubated worms compared with the offspring of control worms. This was selective as there was no difference in H3K27me3 expression.
Obviously this is just a start, one would think that the advantage of the worm is that you could go out for generations quite readily, in comparison with rodents (see below). So presumably this story will advance by the time we see it in publication. Nevertheless, this joins a growing appreciation of the transgenerational effects of drug. While there are many caveats in translating this to humans, it certainly puts a bright spotlight on familial abuse patterns and our potential targets for explaining them.
__
Related: Heritability of Substance Abuse Meets Epigenetics?
*The speaker identified himself as a first year graduate student. I think he did a bang up job of the presentation and of handling the questions.
Experimental Biology 2014: Non-alcoholic fatty liver disease
April 29, 2014
I learned something at poster session 1116. Alcoholic and Nonalcoholic Fatty Liver Disease
Tue, Apr 29, 7:30 AM – 4:00 PM.
Tue, Apr 29, 12:45 – 3:00 PM 1116.11/A601 – Low copper and dietary sucrose drive fibrosis pathways in a rat model of non-alcoholic fatty-liver disease
Tallino and Burkhead presented a poster studying non-alcoholic fatty liver disease in a rodent model. I’m most used to considering similar damage in the context of alcohol exposure, given that abused drugs are my focus. So it was interesting to learn that some 20-25% of those on a Western diet may exhibit some signs of fatty liver disease that has nothing to do with alcohol.
The study Tallino and Burkhead conducted was based on evidence that steatosis may be related to copper (Cu) deficiency and that this may interact with sucrose in the diet.
The study consisted of four groups of Wistar rats, exposed to different dietary conditions for 12 weeks. The factors were a diet either sufficient or deficient in Cu and a 10% or 30% sucrose addition.
The authors show that low Cu diet works, serum Cu was significantly lowered in these groups. Interestingly there was an interaction whereby the group with low Cu and 30% sucrose diet was further depleted in serum Cu. As expected, serum glucose was elevated with 30% sucrose but this was only out of the normal range with the low Cu / 30% sucrose group.
Interestingly, these dietary conditions resulted in no change in free fatty acids and no change in body weight. Remember that now.
The low Cu diet increased liver steatosis significantly with an interaction with the sucrose treatment to increase this sign of non-alcoholic fatty-liver disease. So Cu deficiency can combine with high sucrose in the diet to produce liver damage in the absence of other indications of a fatty diet (weight gain, high circulating triglycerides).
The study then went on to find that the high sucrose, low Cu diet was associated with alterations in gene transcripts related to fibrosis progression, hepatic stellate cell activation and a few other things related to the hypothesized model of damage.
DrugMonkey 