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Brains of male mice boast extra nerve insulation 01 February 2006

The brains and spinal cords of male mice contain more of the protective, fatty substance called myelin, which insulates nerve cells, than their female counterparts, new research reveals. The finding could help to explain why some neurological diseases, including multiple sclerosis, strike one sex more than another.

Robert Skoff of the Wayne State University School of Medicine in Detroit, US, and colleagues found an unexpected difference when they compared the composition of white matter in the brains of male and female mice. White matter consists of nerve cells coated with insulating myelin, which helps the cells to relay signals efficiently.

Skoff’s team determined the density of oligodendrocytes – cells which produce myelin – in the male and female mouse central nervous system by testing for their molecular signature. They found that these specialised cells are roughly one-third more dense within the brains and spinal cords of male rodents. They add that the differences are present in young and old mice, and independent of strain and species.

On top of that, oligodendrocytes appear to live longer in male mice. According to Skoff, the turnover of oligodendrocytes is twice as great in female mice.

The reasons male brains contain more oligodendrocytes – which in turn means more myelin – are unclear. Skoff speculates that selective pressures may have caused males to evolve more myelin, which may mean better nerve-signal transmission in parts of the brain and faster reaction times.

Testosterone influence

The new study also reveals how hormones can regulate the composition of the brain’s white matter. Castrated male mice showed a greater turnover of myelin-forming cells than their normal male counterparts. This suggests that testosterone can influence the amount of white matter produced in the brain.

Skoff says the findings from their study could shed light on why some human neurological disorders commonly affect one sex over the other.

One such illness is multiple sclerosis, which affects about twice as many women as men. With MS, an apparent autoimmune reaction against myelin leads to disrupted nerve pathways and loss of coordination.

Skoff says the findings help to explain why hormone therapy has yielded promising results against multiple sclerosis in experimental trials. He explains that further studies in mice will shed light on how these treatments work. “We can sort out exactly which hormones are regulating these changes,” he says.

Journal reference: The Journal of Neuroscience (DOI: 10.1523/jneurosci.2219-05.2006)

Source: NewScientist.com



PS I really shouldn't have had that castration

Bromley

Thanks so much! I'm elated someone besides me is reading about hormones.

And, I thought I'd given a minor warning about that castration you had when I posted info that testosterone might be a factor in axonal regeneration.



I certainly hope so and it's about time IMO. Unfortunately, like with all things MS, I don't think it's going to be easy. Several hormones are manufactured de novo in the brain (DHEA and progesterone among them) so measurements of serum levels when they try to sort this out will not necessarily reflect the concentration of hormones in various regions of the brain.

I am trying to stay on the look out for the outcome of the testosterone trial at UCLA but so far I haven't seen anything.

Take care Bromley--I actually thought we could start a new theory about MS since I was a scuba diver too.

Sharon

Sharon,

Can they test for levels of testosterone?

I've still got a full head of hair at 40 so perhaps my levels are on the low side? Do bald men get MS?

I got to 99 dives in my dive log book. Perhaps it was the pressure at 35 metres down that triggered my MS?

Ian

Ian, you beat me by 12 dives. I have 87 in my log book. Might be something to do with my aversion to dry suits and the water temeperature in Britain.

There may well be a bus at the bottom of Stoney Cove but I'm way too much of a wimp to go look!

You didn't seem to be going bald when we met. You must've had the good wig on that day then!

Robin.

_________________
Do not go gentle into that good night. Rage, rage against the dying of the light.

Robin,

You also had a full head of hair so perhaps my bald men don't get MS theory is true!

There's also a plane at the bottom of Stoney Cove, but only a member of the British Sub-Aqua Club would attempt a dive in such cold dangerous waters.

When they finally put an end to this curse perhaps you, me and Sharon can spend a week off Ningaloo reef in Western Australia. I'd never seen so many sharks and Whale Sharks are guaranteed at certain time of year.


Ian

Yeah, BSAC.. Them guys that wear toilet seats round their necks rather than a stab jacket..

After Ningaloo, we really should try Kisite marine park in Kenya. The most unspoilt dive spot I've ever seen. I also got to swim with dolphins there. A truly fantastic experience.

Robin

_________________
Do not go gentle into that good night. Rage, rage against the dying of the light.

Robin,

Perhaps boasting triggered off your MS?

With double incontinence waiting in the future, perhaps wearing a toilet seat round one's neck is not such a bad idea!

Ian

Oooh, do I take it that you're BSAC rather than PADI ???

I make no secret of it, I'm a fair weather diver (or was!) Warm water and good viz or I'll sit on the boat with a coffee thanks...

p.s. No I wasn't boasting, I was totally blown away by Kisite. If ever anyone who dives goes to Kenya for a safari, take the time to go to Kisite. It really is magnificent.

Robin

_________________
Do not go gentle into that good night. Rage, rage against the dying of the light.

Hi Ian,
Sorry to spoil your theory on baldness but I'm 43 and I've been going bald since I was 23. I had an older brother (deceased) who was going bald and a twin brother likewise and all of us have MS. I just buzz what hair I have left, it is so much easier to care for. As for testosterone, I've been a serious weight lifter my whole adult life and I hear that it builds your testosterone level. Some of the guys i've met at the gym over the years could use a little less testosterone IMO. As I have gotten older and now have a wife, two growing kids and my own business I haven't had as much time to lift as I used to. Maybe thats why I was finally dx with MS at 42 after many years of minor symptoms. Maybe the lifting held it in check. Who knows?
Terry.

Terry,

I thought I was on to something with my baldness theory (based on my sample of two).

Perhaps I could combine Rebif and Regain in one injection for men with MS who are losing their hair?


All the best

Ian

Ian, Robin and Terry

A few quick quips--

The bald theory is out. The scuba theory is still in (sample of 3)... 2 men with more dives and thicker myelin than one old woman with fewer dives and thinner myelin to boot than either of the men. I was strictly a sport diver (PADI) with good visibility a must.

Ningaloo was on my "to do" list; I didn't know about Kisite--on to the list it goes. Either one or both are fine with me after we conquer MS. I can hardly wait.

And yes, Ian, you can have your testosterone levels checked. Of all the ones I had tested only testosterone was within the normal range for a woman my age.....go figure. All others were whacked out one way or the other. Those hormone level results have kept me reading for a good long time.

Terry--I think exercise can definitely be a good thing for people with MS.

Take care all

Sharon

PS--I don't plan to be wearing a toilet seat when we meet for the diving. A nice wet suit will be just fine IMO.