The Brain's Gender May Be More Flexible Than Previously Thought

http://www.iflscience.com/brain/brain-s-gender-may-be-more-flexible-previously-thought

Kristy Hamilton for iflscience.com

01-04-15

QuoteThe researchers injected Dnmt inhibitors into the POA, a brain area known to be involved in governing male sexual behavior, after the first week of birth, after the window for brain sexual differentiation was thought to have been closed. Despite this, the POA in the animals was transformed, and took on structural characteristics of a male rat. The female rats also behaved differently, displaying sexual behavior typical of male rats.

In another experiment, they scientists deleted the Dnmt gene in female mice; these animals also showed male behavior patterns. "Pharmacological inhibition of Dnmts mimicked gonadal steroids, resulting in masculinized neuronal markers and male sexual behavior in female rats," the authors of the Nature Neuroscience article wrote. "Conditional knockout of the de novo Dnmt isoform, Dnmt3a, also masculinized sexual behavior in female mice."

Modified to fix news formatting guidelines

Love this.
My favorite line from the article:
"...studies like this reveal just how flexible the brain's gender is and", according to Nugent, "gives us a new understanding of how gender is determined in the brain."

NOT the genitals.

Also, the original study can be found here:

Brain's 'gender' may be quite flexible: Mechanism that plays key role in sexual differentiation of brain described

Date: March 31, 2015
Source: University of Maryland Medical Center/School of Medicine
Summary:
During prenatal development, the brains of most animals, including humans, develop specifically male or female characteristics. But scientists have known little about the details of how this differentiation occurs. Now, a new study has illuminated details about this process. Researchers succeeded in transforming the brain of a female rat after an important developmental window had closed, giving it the characteristics of a male rat brain.

http://www.sciencedaily.com/releases/2015/03/150331121249.htm

Isn't it kind of cruel to try and give poor innocent little rats gender dysphoria?

Quote from: marsh monster on April 02, 2015, 02:49:21 PM
Isn't it kind of cruel to try and give poor innocent little rats gender dysphoria?

Yeah, probably.

I wonder how long after birth these treatments are successful?  Could people try to use this as a gender dysphoria cure?

Of course, the male rats can't complete the maze because they won't ask for directions! 

Quote from: Anna++ on April 02, 2015, 03:01:43 PM
Yeah, probably.

I wonder how long after birth these treatments are successful?  Could people try to use this as a gender dysphoria cure?

What if this "cure" was to be forced upon people who did not want it? 

I would never want my personality changed.   I actually like being a girl now and changing what fundamentally makes me myself sounds much worse than enduring the necessary treatments for GD and society's problem with that.

Quote from: Jill F on April 02, 2015, 03:07:49 PM
What if this "cure" was to be forced upon people who did not want it?

I would consider that to be malpractice. 

Quote
I would never want my personality changed.   I actually like being a girl now and changing what fundamentally makes me myself sounds much worse than enduring the necessary treatments for GD and society's problem with that.

That's a discussion for another thread.  I'm just curious how far the research went, since I didn't see that in the article.

Quote from: Anna++ on April 02, 2015, 03:01:43 PM
Yeah, probably.

I wonder how long after birth these treatments are successful?  Could people try to use this as a gender dysphoria cure?

To my mind that would be the same as earlier attempts to 'cure'  GD  by the use of electric shock treatments.

Yes be very careful around this one. Big_pharma would LOVE a drug that could do that, and they would push for it to be made mandatory first line treatment. It's great in the sense that it reinforces that biological nature of aspects of sexuality. Its not so great when someone then goes on to develop a "cure".

Besides which, from where I sit, this actually hasn't changed the rat's gender - it has changed their sexual orientation - no more than that, and as usual the "never been anything but cis-hetro" numbskulls have ASSUMED that because the female rats now mount other females that must make them "male".

Well no actually - that more probably makes them lesbians actually - so I think I might suggest these researchers go back to school and learn the difference between gender identity and sexuality, which they are clearly wrongly linking.

Does this sentence strike anyone else as odd:

She found that giving estradiol, a testosterone derivative, triggers a mechanism by which certain genes in the brain are "unsilenced," allowing them to initiate the process of masculinization.

I've come across quite an interesting paper, talking about the role of hormone receptors in masculinization of the brain, and an important species difference between rodents and human beings. In humans, brain maculinization appears to be more or less entirely driven through the action of androgenic hormones (testosterone and DHT) on androgen receptors. This is shown by the way genetically male people with Complete Androgen Insensitivity Syndrome (CAIS) not only look female, they have feminine behaviour and regard themselves as female. By contrast, rodents with the analogous mutation (Tfm) look female, however they show at least partial masculinization of many behaviours. The authors of the paper argue that the difference arises because, in rodents, both androgen and estrogen receptors play a role in masculinizing the brain, and extensive brain masculinization can occur in rodents even when the androgen receptors are completely nonfunctional.


This research is yet another piece of evidence showing how the sex of your brain depends on what hormones were present during the critical period when your brain development was taking place, not on whether you have a Y chromosome or not. It also helps explain why there's probably a lot of genuine confusion among scientists about the effects of DES exposure on the human brain (DES is an artificial estrogen that was widely used as a treatment for preventing miscarriages up until about 1980, and has since been linked to MTF transsexuality). In rodents, females exposed to DES in the womb end up with masculinized behaviour. In humans, the opposite appears to have happened (see for instance https://www.susans.org/forums/index.php/topic,84224.0.html ), which I think is due to it suppressing androgen production.

How did my post (which is completely unrelated to the IFLscience article, and I started as a separate topic), end up as part of this one?

Quote from: HughE on April 08, 2015, 10:14:46 AM
How did my post (which is completely unrelated to the IFLscience article, and I started as a separate topic), end up as part of this one?

They like to keep similar things in one topic so they moved it. Both are about rats and gender, I guess.

Quote from: HughE on April 08, 2015, 10:14:46 AM
How did my post (which is completely unrelated to the IFLscience article, and I started as a separate topic), end up as part of this one?

Reason for merger,
"If either from the search or a cursory glance of the news forums, turns up an existing post about an article that is on the same subject as the one you'd like to post, do not create a new thread. Instead, post a reply in the existing thread and format it as if you were starting a new topic. (i.e. original topic: City or State votes on transgender bill, article as a reply: Same City or State passes transgender bill)."

Rules of the News section are listed here and will be strictly enforced by staff. Please take the time to read over.
https://www.susans.org/forums/index.php/topic,174951.0.html

Staff can make moves as they feel are need to keep subject matter together.  Also your topic was a comment and did not fit a format and was edited out of the link to keep with-in the rules of fair use and quoting. Staff did this merger but could have just as easily removed for lack of the News Posting & Quoting Guidelines

"The Role of Androgen Receptors in the Masculinization of Brain and Behavior: What we've learned from the Testicular Feminization Mutation" that I was talking about (Staff edit of: do a google search)

It's quite an interesting paper, partly because it's yet another piece of research showing that the sex you develop as is determined by hormones and not by whether you have a Y chromosome or not. More importantly though, by comparing the effects on behaviour of the Tfm mutation in rats and mice with the equivalent mutation in human beings (CAIS), they've shown that there's an important species difference in the way brain masculinization works between rodents and people, that means that a great deal of care needs to be taken extrapolating any research on brain masculinization in rodents to human beings. In rodents, brain masculinization is mainly driven through the action of estradiol on estrogen receptors (although, as this paper shows, androgen receptors play a role too). In human beings, it's essentially entirely driven through the action of androgenic hormones (testosterone and DHT) on androgen receptors.

This is something that I suppose is applicable to the IFLscience article, however, it's equally applicable to every bit of research into brain masculinization that's been carried out over the last 50 years using rats or mice as the lab animals. Basically, it means that rodents are a poor choice for understanding how the process works in human beings, and any research on brain masculinization that's been done using rodents should be taken with a grain of salt (especially if it involves estradiol or estrogen receptors).

This is particularly relevant to understanding the effects of DES, since it explains why we have the seemingly paradoxical effect of it causing male brain development in female mice and rats,  whereas in human beings, it's seemingly had the opposite effect and caused female brain development in biological males. 

As for the IFLscience article, they used rats and mention estradiol, so it probably doesn't have much relevance to humans. "I can't understand why people are acting like the process is a mystery though". It's been known for over 50 years that whether you end up with a male or female brain is determined by what hormones were present during the critical period when your brain was developing, as mentioned in this paper:

Staff Edited and removed links again..

The terminology used in the article is weird.

Lesbian rats are female rats.

Did they actually find that excess of estrogens in a particular early development phase of female rats may induce aggressive homosexuality?

The enzyme in question is more relevant for curing cancers.

Wait a sec, I thought rats were born in an altricial state & thus sexual differentiation of the brain occurs postnatally???