Question

| 24 hr mating 0.24 hr mating Cohab without mating Partner O Stranger O Partner Stranger 90 - Side-by-side contact (min) Side-by-side contact (min) Saline Halo CSF D2 ant CSF D2 ago A. Why do you think dopamine signaling in the nucleus accumbens plays a part in pair-bonding in Prairie voles? I B. What effect did an intra-nucleus accumbens injection of haloperidol have on side-by-side contact time between partners and strangers (Fig A)? What does this indicato? c. Interpret Figure B from the above image. 1) What effect does an intra-nucleus accumbens D2 antagonist injection have on pair bonds? 2) What effect does an intra-nucleus accumbens D2 agonist injection have on pair bonds?

Answer 1

A. Dopamine is a neurotransmitter that is related with motivational component of a reward-motivated behaviour od a subject or individual. Nucleus accumbens is related with this reward-receiving or praise receiving part of the hypothalamus of the brain. Dopamine when induced into the nucleus accumbens of Prairie voles, binds with the dopamine type 1 receptor present in the nucleus accumbens that induces a cAMP dependant signalling pathway, enhancing the pair-bonding behaviour.

B. Haloperidol is an antagonist of Dopamine. This means that this drug inhibits the functioning of dopamine and stops the nucleus accumbens to respond to the partner-stranger pair-bonding. From the graph, it is clear that induction by Halo has greatly reduced the efficiency of the Prairie voles to receive the motivation of partnering up with the other vole and thereby the partnering capability has turned significantly into stranger effect.

C. According to the second figure:

1. An intra-nucleus D2 (Dopamine receptor 2) antagonist normally functions in inhibiting the function of the dopamine receptor.So as per the fighre B, during 24hour mating, in presence of a non-induced CSF, partnering up probability is much more and being a stranger is almost negligible.This means, the D2 antagonist has a negative effect on the pair-bonds and increases the probability of being a stranger and also decreases the chances of partnering up during mating at the same rate which gives almost equal height bar graphs.

2. A D2 agonist, something that activates or enhances the dopamine receptor to bind to the neurotransmitter easily and at more concentration, is also used in this experiment. In the second half of the graph in figure B, the experiment is conducted without mating and only cohabitation. So the chances of partnering up to just have a cohab would not be much and would almost be same as the stranger effect because there is no mating inolved. But when the D2 agonist is added, the dopamine receptor charges up, binds with any dopamine molecules released and increases the extent of pair-bonding withing non-mating Prairie voles to a greater extent.