The Dead Rat Society

Day 26

A white room somewhere

1hr 42 minutes into the light cycle

 

When I woke up, I thought it was going to be a normal day in my cage. I made my way through my morning routine: drinking water, eating pellets. I peered over at my sisters, F344-12-2, F344-12-3, and F344-12-4. They were still sleeping soundly. Having eaten my fill, I crawled back into our black house (or is it red? I can’t really tell…) and dozed off between F344-12-2 and F344-12-4.

 

I was awoken by the sound of metal shifting above me. A large, pale pink thing with many projections descended into our home and grabbed me by my torso. “EEeeeeEEEp!!!” I screamed. My world turned upside down as I struggled to free myself by wiggling from side to side, but the thing did not let go. I had seen this thing before; it had taken away my mother and my brothers, although occasionally I could hear what sounded like their voices in the distance. It was an enigma.

 

I found myself in an area a fraction of the size of my home. It was entirely new to me. I was afraid. Why is this happening? What does the thing want??? I’d never been more anxious in my life— and I’m usually pretty anxious. I sat for what felt like an eternity waiting for something interesting to happen. Nothing. I nodded off.

 

After I couldn’t sleep anymore, I curled up underneath the water bottle. I was so lonely, and the slow, steady dripping of the water on the back of my neck was reminiscent of social interaction. My sisters and I didn’t play together very often. They’re pretty anxious, like me. But this isolation was having some strange effect on me. I wanted to play. I wanted sensation. But the water drops were all I had.

 

I could hear voices all around me, but I couldn’t see anything. I had the bare necessities for life in this chamber, but no friends. Is it worth it to be alive when there is no one to play with?

 

Just when I thought I couldn’t take it anymore, the thing swooped in and grabbed me again. I didn’t struggle. I had given up.

 

In a matter of seconds, I was dropped into a large, open chamber with another rat! She had a funny, black mohawk. I’d never seen anything like it before and it frightened me. She introduced herself as Sprague-Dawley-40. She was extremely friendly. Other than this difference of character trait, we were remarkably similar. She told me she’d gone through all of the same experiences as I had. As a pup she and her sisters were tragically separated from their mother and brothers. And in the past 24 hours, she, too, had been extracted from her home and placed in isolation.

 

While she was explaining all of this to me, she repeatedly pounced on the nape of my neck. It was apparent that she wanted to play even more desperately than I did. For a while, my social anxiety held me back but eventually I could ignore her play solicitations no longer. “EEeeeeEEEp!!!” I rolled over on my back in response to her next pounce and we tumbled raucously for the next 10 minutes, taking turns and pouncing on and pinning each other.

 

But our play was suddenly interrupted. We heard a beeping sound in the distance, beyond the darkness of our chamber. We froze and stared in awe as the sky opened up above us and bright light poured in. The terrifying pink thing was back! Sprague-Dawley-40 quickly flipped back onto her feet (we had paused mid-pin) and we both scrambled away from the descending monstrosity. The thing grabbed Sprague-Dawley-40 and I watched as she rose above me and disappeared into the light. For a split-second, I believed I was safe. Then the pink thing appeared again, but my new friend was nowhere in sight. It descended and wrapped its appendages firmly around my torso. My feet lost contact with the ground as I, too, was brought into the light.

 

I was forced back into my isolation chamber. Before I could gather my thoughts, however, the pink thing grabbed me yet again. It pulled up and up and finally, thankfully, placed me back in my home chamber, safe at last, and reunited me with my sisters. “You won’t believe the day I had!” I squeaked. “Same!” exclaimed F344-12-2.

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A typical day in the life.

 

The Dead Rat Society

Hello, yes…. We are the “dead rat people.”

Dr. Steve Siviy is our PI and “captain.”

Supporting roles by Sam Eck, Lana McDowell, and Jenn Soroka.

 

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Hitching a ride in Jenn’s labcoat.

 

Welcome to our “blog,” where we will share the diary entries of our lab rats, and occasionally talk about science. For a psych lab, we are surprisingly interdisciplinary- dabbling in biology, chemistry, histology, and neuroscience as well as psychology.

Instead of embodying the sage advice that work comes before play, here we like to do both simultaneously. Our research investigates the behavior and neural mechanisms surrounding play, with rats as our model. Development of an adaptive behavioral repertoire and situational flexibility is an important characteristic of social growth. As such, adolescent rats spend a lot of time engaging in interactive social behaviors, social investigation, and social contact behavior.

Fischer 344 (F344) rats, like the heroine in the story, are a common choice for exploring anxiety being inbred especially for the trait. But what makes F344 rats particularly interesting, in our eyes, is that they also don’t play as much as other strains. By reaffirming the behavioral differences and investigating possible neural differences, we aim to gain a better understanding of the mechanisms of play.

The inbred Lewis (Lew) rat strains and the outbred Sprague-Dawley (SD) strains are also used in testing. Lewis rats provide the primary comparison for our F344s, but SD rats make ideal controls and rat play partners, as they are the most genetically divergent and naturally playful of the bunch.

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Our IACUC certifications. We like our job.

 

Here’s some background knowledge about some of the testing we put our rats through, that will make reading the rest of this blog more digestible:

Play bouts: The main event in our lab. We video-tape pairs of rats playing together for 10 minute periods and code their behavior later in quarter-time, because rats are wicked fast. Rat play looks a bit like wrestling; they pin each other and perform nape contacts. Lab lackeys Lana and Sam record instances of play behavior, as well as which rat initiates playing (SD “target” rats are marked with black sharpie for quick differentiation).   The rats are often isolated for 4 or 24 hours before play. They find it naturally rewarding, but are more inclined to play after being deprived of social interaction (much like how you would immediately approach food if you were starved for 24 hours).

Elevated Plus Maze (EPM): We know this is a lot of info, but try to follow along. It’s a maze… that’s plus shaped… that’s elevated off of the ground. Two of the arms are “closed,” and have walls. The other two are “open,” kind of like walking a plank. Rats are naturally curious and will want to explore their environment in the open arms, but the more scared they are the more they’ll want to be protected in the closed arms. This ratio of where they spend their time is a good indication of anxiety.

Open Field (OF): Another good indication of anxiety. We put the rats in a dark square box and a camera records their movements. Less anxious rats usually spend more time “exposed” away from the edges of the box.

We are currently juggling a few projects:

 

Oxytocin

Some background on oxytocin: it’s both a neurotransmitter and a hormone, and is involved heavily in pair bonding (aka: love). Some could argue it’s the new, hot, sexy thing in science.   We suspect that oxytocin may also be involved in the complex behaviors of play.

To evaluate if any differences in baseline oxytocin levels exist between the more playful Lew rats and the traditionally less playful F344 rats, we look to the paraventricular nucleus in the hypothalamus of the brain (where all said oxytocin lives).

You can’t exactly look at the paraventricular nucleus of a live rat. So Jenn gets to play God.

 

After undergoing behavioral testing (see above), we perfuse the rats with phosphate buffer saline (PBS) and Paraformaldehyde (PFA). This replaces their blood with PBS and PFA consecutively, and the brain is fixed and can be removed from the skull. After a healthy dose of PFA, the blocked brains are cryo-protected with increasing percentages of sucrose solutions (so the cells won’t burst when we slice the brains). We then slice the brains, with the scientific equivalent of a deli meat slicer known as a cryostat. It slices brains and salami at 40 microns thin. (Sam swears by it for all of her sandwich making needs, and you can get one too for the affordable price of ~ $35,000. It pays for itself, I reckon.).

 

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Very cheap meat slicer for sale. Contact Steve Siviy for details.

Immunohistochemistry is used to stain the oxytocin positive cells brown, so we can count them. More on that thrilling quest later.

Cross Fostering

Most of us are familiar with the concept of “Nature v. Nurture.” We aim to determine just how much of a rat’s play behavior is influenced by maternal care at a young age. If maternal behavior is very important, the rats that are given more attention would be expected to become more playful.

We ordered timed-pregnancy F344, Lew, and SD females (yes, there’s an industry for that), who all gave birth to their litters at around the same time. But when they were only a few days old, we swapped the mothers’ original litters out for a new batch.

Some mothers were given a litter that was a different strain from their own (eg. a Fisher 344 mom assigned Lewis babies). This is called cross-fostering. Other mothers were given a litter that was the same strain (eg. a Fisher 344 mom assigned Fisher 344 babies). Much like human mothers, they didn’t notice much of a difference.

Just kidding, we love our mommies. Shout out to Cyndi, Wendy, and Maia.

We had to come in 5 times a day and take hour-long observations of each mother’s behavior, including whether she was in or out of her nest, what type of nursing she was exhibiting, and if she was licking/grooming her young.

 

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A mother passively nursing pups.

Presently, the babies are all grown up and are going through behavioral testing. We’ve video-taped them playing in pairs, and are starting to put them through elevated plus maze testing and open field testing.

 

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Baby rats hiding safely in their “black” house after they’ve been weaned. Rats are dichromats, and perceive the world with red-green color blindness.

 

Cocaine:

We’ll experiment with cocaine later this summer.

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One thought on “The Dead Rat Society

  1. Jenn’s Uncle Jim and Denny just finished reading your blog and have a whole new look on lab rats. Very interesting study and enjoyed the outlook of the experiment from the rat’s point of view.
    Keep up the good work!!

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