Van der Oever

• Aim?

  investigate acute changes in molecular composition and function of synapses in mPFC upon re-exposure to heroin cues after long-term abstinence from self- administration.
• procedure? (1)

  1. self administration (SA). 1 group trained to SA heroin and presented w/ audio-visual cue+ poking nose in hole would release dose of heroin in catheter. control group do same with sucrose solution.
• procedure?(2)

  2. abstinence. (3 weeks) group divided into 2. 1g in separate cage for 21 days (abstinence, cannot poke hole) 1g put in SA box for 21 days but didn’t receive solution when poking hole (extinction, unlearning that nose poke is equal to heroin).
• procedure?(3)

  3. re-exposure. 2 groups split to 2. 1/2 abstinence 1/2 extinction re-exposed to cues for 1 hour and didn't receive heroin. other half in SA box but not exposed to cues. didnt receive heroin.

  control to confirm if synapse change=cue
• procedure?(4)

  4. analyse synapse. straight after rats are decapitated and brain is frozen to analyse. detected subtle changes in receptor of synapse at mPFC and analysed using mass spectrometry to identify amounts and types of chem present
• results and conclusion?(1)

  R: after period of abstinence/extinction exposure to cues significantly increases amount of drug seeking behaviour compared to SA drugs but not exposed to cues.

  C: after period of abstinence/extinction exposure to cues can trigger relapse back to drug seeking behaviour.
• results and conclusion?(2)

  R: rats that SA heroin, period of A/E and exposure to cues= decrease in avg AMPA. rats that SA heroin, period of A/E and no exposure to cues= normal AMPA receptors. rats that had sucrose had of A/E and no exposure to cues had normal levels of AMPA so changes in AMPA specific to drug heroin.

  C: molecular composition/function of synapses are changed. rats re-exposed to cues related to heroin after period of time so linked to decreasing number of AMPA receptors on post synaptic neuron near mPFC.
• results and conclusion?(3)

  R: rats that weren't injected with drug to prevent endocytosis had increase with significant relapse compared to rats that were.

  C: reduce in AMPA receptors in mPFC as a result of being exposed to cues means a relapse. synapses in PFC are a potential target for therapeutic drugs.
• evaluation

  G: crucial area of brain in rats and humans are similar but only male of species wistar rats so not representative. rats and humans can differ.

  R: standard proc(21d) any weakness???

  A: can prevent drug addicts from relapse and drug therapy can be used to prevent but studying rats may not work as well for humans.

  V: control group so ext v reduced. reductionist to only focus on biological factor but can be limited in explanation.

  E: sample in rats so costs and benefits weighed however unethical as causing harm to rats and damages rep.