Sex Differences in Pain Perception, and More

IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, we’re going to answer all of your questions about recycling.

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But first, it seems like if you’re going to test drugs that both men and women will take and you’re going to animal tests on those drugs– do the tests on those animals first for the drugs– you might want to test them on both male and female mice, right? But that’s not always the case, because some researchers claim using female mice would bias their results– give less accurate, more reliable results, a claim that it turns out doesn’t have much merit.

Virginia Hughes is here with that and other selected short subjects in science. She’s the science editor at Buzzfeed News here in New York. Welcome back, Ginny.

VIRGINIA HUGHES: Hi, Ira.

IRA FLATOW: What’s this– your first story about male and female lab mice and pain research?

VIRGINIA HUGHES: Yeah. So this week, a big pain researcher in Canada wrote a cometary in Nature calling for more researchers to use female mice in their studies of pain. And as you mentioned, all other kinds of studies, too– biomedical research in general– it’s really interesting– historically, the vast majority of rodent studies have been with male rodents only. And the thought was, well, female rodents have hormonal cycles that will mess up the data. They just are too variable, and we’ll have to use too many animals to smooth out that variability.

But it turns out that’s not the case. Some newer studies have shown that the female mouse and rat data is no more variable than male. But yet researchers are slow to change what they do, I think. And so most studies are still using mostly male animals.

IRA FLATOW: Even though the research shows that male and females process pain differently?

VIRGINIA HUGHES: Yeah.

IRA FLATOW: Very big difference.

VIRGINIA HUGHES: It’s pretty interesting, both in– and there’s many reasons for why that might be. But the human studies generally show that women seem to be more sensitive to pain, or more frequently reporting their pain. So that could be for cultural, societal reasons– if women are just more apt to go to the doctor or talk to their doctor about pain and maybe men are– they feel like it’s not macho to talk about being hurt.

But it seems like there’s some biological differences, too. These studies in mice and rats have shown differences in what cells in the spinal cord process pain. And so it’s tricky piecing– trying to separate out what’s driving these differences. And the idea is that we need to study both–

IRA FLATOW: Both of them.

VIRGINIA HUGHES: Both.

IRA FLATOW: And the NIH now requires studies to use both male and female mice, right?

VIRGINIA HUGHES: Yeah. In 2014, they issued rules that, with a few exceptions, any research– animal research that’s funded by the NIH– has to take sex into account in some way. So those don’t go into effect until this year. So the research– it’ll be a few years before we see that hopefully show up in the literature.

IRA FLATOW: Now, I understand there’s also been a backlash among some women in the science community who don’t like that dual requirement.

VIRGINIA HUGHES: Yeah. It’s really fascinating. There are some researchers and kind of feminist scholars who say, hey, wait a minute. What this policy could do inadvertently is make researchers look for differences where they might not actually exist or put a focus on supposed biological, hard-wired differences that are actually much more likely to be caused by cultural drivers. And so if we’re looking for hard-wired differences where they don’t exist, that could actually backfire in the long run.

IRA FLATOW: OK. Let’s move on to your next story. It’s about a recent cancer immunotherapy trial which had a few tragic deaths– four. Four of them now, right?

VIRGINIA HUGHES: Yeah. It’s awful. I’m sure you have talked about immunotherapy a lot on this show.

IRA FLATOW: Yes, a lot.

VIRGINIA HUGHES: It’s, I would say, widely hailed as a breakthrough in cancer research. And one of the hottest kind of clinical trials in this area is now– so last week, the FDA halted a clinical trial of an immunotherapy because– while at the time, it was thought that three patient volunteers had died, the company has since updated that this week, and actually four had died from brain swelling. So their brains, I guess, filled up with fluid. And then this week, somewhat unexpectedly, the FDA decided that that trial could continue. So after just– I think the FDA looked at the company’s proposal for two or three days and then decided that it could go on with a change in the protocol, which is pretty fast.

IRA FLATOW: If you had two or three days, they have to [INAUDIBLE] works, then.

VIRGINIA HUGHES: They certainly don’t respond to journalists in two or three days.

IRA FLATOW: Any idea why? Is there a bunch of politics involved here, or who knows?

VIRGINIA HUGHES: Of why they switched it? Yeah, the FDA isn’t really giving many details about why. But presumably it’s because they thought that the company’s explanation of what happened made sense.

So this particular treatment is called CAR T. And what happens is you take a leukemia patient’s blood out of them, you tweak their immune cells to make them better able to attack the cancer themselves, and you put the blood back. And in this particular trial, the patients who died had all taken a very specific chemotherapy drug right before the trial. So they think it was something about the interaction between that drug and these cells.

IRA FLATOW: I see.

VIRGINIA HUGHES: So they’re saying, we’ll just stop using that chemo drug and restart the trial, and hopefully it’ll all be better.

IRA FLATOW: And your final story is about eBay, the place where you can buy– well, just about everything or anything, except now you can’t buy human skulls. I was just going to order one this afternoon!

VIRGINIA HUGHES: They’re expensive.

IRA FLATOW: Well, what happened?

VIRGINIA HUGHES: So as of last week, if you had gone onto eBay and typed in “genuine human skull,” about a dozen different listings would have popped up selling these, in fact, genuine human skulls. Selling human remains is illegal in most states. It has a pretty bleak history of grave robbing. And it goes back a really long time.

And bioethicists and others have been really upset about eBay selling these things. For more than a decade, they’ve been raising concerns. So this group of forensic scientists did a survey of these listings on eBay. And they found– they looked for a seven-month period and found 454 listings of human skulls. Can you guess what the average opening bid was for a skull?

IRA FLATOW: $100.

VIRGINIA HUGHES: $650.

IRA FLATOW: $650!

VIRGINIA HUGHES: And one of them was $5,500, so very expensive.

IRA FLATOW: Wow.

VIRGINIA HUGHES: Yeah. So one of our–

IRA FLATOW: They don’t want it now, though.

VIRGINIA HUGHES: Yeah, they stopped it. They stopped it this week.

IRA FLATOW: That’s good to hear. Thank you, Virginia.

VIRGINIA HUGHES: Oh, thank you.

IRA FLATOW: Virginia Hughes is the science editor at Buzzfeed News here in New York.

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