Hi, I worked with the DA system -behaviorally, electrophysiologically, pharmacologically and electrochemically at Univ Pittsburgh in the days when Dopamine was their main topic. Yes, many many methods and procedures to standardize responses.  Activation, habituation, handling, pressure to the tail, etc. all play key roles.  Happy to discuss this with you by phone - 317 276-5192  Nancy Ostrowski

Hi, I worked with the DA system -behaviorally, electrophysiologically, pharmacologically and electrochemically at Univ Pittsburgh in the days when Dopamine was their main topic. Yes, many many methods and procedures to standardize responses.  Activation, habituation, handling, pressure to the tail, etc. all play key roles.  Happy to discuss this with you by phone - 317 276-5192  Nancy Ostrowski

Hi Nisha, you may find this article interesting:

Hi Nisha,

Are you works with male or female rats?

Age, gender (female or male) and bioterio ist the same?  depend of experiment researcher could be the same.

Thank you all for your responses!

Elwood, I am in fact aware of this issue, I read their original paper which made me more scared specially when it comes to publication. I run all my experiments and maintain the colony. However, our animal care facility provides the day-to-day maintenance (cage changes). They have different techs working so haven't controlled for male/female personnel handling animals at that level.

Article Olfactory exposure to males, including men, causes stress an...

Daniel, I primarily work with male rats. I did some biochemistry with females and had a feeling that success of my experiments correlated with their fertility (the ones which could never have a litter, showed negative results). Not sure if this was real but stopped using females and continued to males. However, see variability in physiology (hippocampal synaptic transmission) and biochemistry in them too.

Beatriz, the variability I see is in age matched males or age matched females. So age and gender cannot account for the variability.

I have also noticed that whenever I use animals bought from a company, they show responses different from what I see when I use our in-house litters. I do allow them to acclimate for at least a week between arrival to our facility and running experiment. Since a lot of confounding factors can be added when we purchase animals, I wonder more about their emotional state, their or their mothers' nutrition etc and whether that could be responsible for variability.

Nisha, maybe the female rats were in different stages of estrous cycle (estus/diestrus I/diestrus II/ or proestrus. I think that you should work whith female rats in the same stage of estrous cycle, or compare your results between different stages.

For example, hypothalamic dopamine changes a lot along the estrous cycle.

Additionally, but not the best, you can work with ovariectomized rats to avoid hormonal variations.