Freethought & Rationalism Archive

Daleth · 06-04-2003, 01:09 PM

Thanks for the link, scigirl. Damn, it's almost offensive to show the levels changing so slightly and knowing what a big effect it can have. I demand a finer scale on the graph so the changes look much more significant.

And none of this is going to help with geriatrics.

Dal

Dune · 06-04-2003, 03:20 PM

<quote>The study doesn't state or hazard a guess at which hormone or which combination of them might cause this specialized hijacking of the brain, but like I said, I think it's bunk. <quote>
That was more the question I was asking rather than what hormones are involved. I am well versed in the biochemistry of the event, I just can't see how that would relate...
So I am agreeing with you as well.

<quote> think most women do have the estrogen surge though (normally the estrogen surge induces the LH surge, but not if you are on the pill). I"ll have to investigate this. <quote>

estrodiol surge stimulates the LH and FSH surges which stimulate ovulation. Oral contraception (either combo E2/progesterone or progesterone alone) block the LH surge preventing ovulation.

<quote>Progesterone is very low during the follicular phase, then goes up a teeny teeny bit during ovulation, then stays up until the luteal phase is over. <quote>
I dont know about teeny teeny bit, secretion does go up about 10x..... But essentially correct.

But like both of you; im not sure how this would cause an increase in forgetfullness. If that where true, wouldn't women's test scores drop?

tribalbeeyatch · 06-04-2003, 03:26 PM

I dunno how credible the study is, but there are plenty of hormone receptors expressed in memory-related areas of the brain.

Dune · 06-04-2003, 03:33 PM

<quote>but there are plenty of hormone receptors expressed in memory-related areas of the brain.<quote>

But I dont believe any of them are receptors for the sex hormones.

scigirl · 06-04-2003, 04:10 PM

Quote:

Originally posted by Dune
But I dont believe any of them are receptors for the sex hormones.

Well there are definitely receptors for sex hormones in the hypothalamus, which is part of the brain - this is how negative feedback works.

Current studies indicate that there are receptors for sex hormones in other parts of the brain.

Para/autocrine regulation of estrogen receptors in hippocampal neurons.

Quote:

Previous studies have shown that estrogens, originating from ovaries, have a wide variety of estrogen receptor (ER)-mediated effects in the hippocampus. In the present study, we have investigated whether estrogens, which are synthesized in the hippocampus, could induce these effects as well. As a parameter, we used ER expression in response to estrogen synthesis, because estrogen receptors are ligand-inducible transcription factors. The experiments were carried out with cultures of isolated adult rat hippocampal cells... Our findings provide evidence for a de novo synthesis of estrogens in the hippocampus, differential regulation of estrogen receptor isoforms by estrogen and consequently for a para/autocrine loop of estrogen action in the hippocampus.

The hippocampus is a part of our memory circuit.

Estrogen receptor beta messenger ribonucleic acid expression in the forebrain of proestrous, pregnant, and lactating female rats.

Quote:

Estrogen receptor (ER)beta is present in hypothalamic and limbic neurons of female rat brains, but little is known about its regulation under physiological conditions... These results demonstrate that ER beta mRNA expression is differentially regulated in a brain-region-specific and temporal manner under physiological conditions and suggest that ER beta may participate in the regulation of estrogen-sensitive reproductive functions in female rats.

The limbic system is important in emotions.

scigirl

tribalbeeyatch · 06-04-2003, 04:12 PM

Quote:

Originally posted by Dune
But I dont believe any of them are receptors for the sex hormones.

Sure they are. Estrogen and progesterone receptors are expressed in the hippocampus.

tribalbeeyatch · 06-04-2003, 04:14 PM

Quote:

Originally posted by scigirl
Current studies indicate that there are receptors for sex hormones in other parts of the brain.

And it isn't only "current" studies. This has been known for decades.

Dune · 06-04-2003, 07:17 PM

Let me clarify my response.
Sex hormone receptors are in the brain, but not involved in memory. Receptors believed to be involved in memory are NMDA and non-NMDA receptors, and estrogen and progesterone are not known ligands for these receptors.
I never intended to imply that sex hormones do not have receptors in any part of the brain or even in the hippocampus- this would be silly.

tribalbeeyatch · 06-04-2003, 08:12 PM

Dune, glutamate receptors aren't the only ones involved in hippocampal memory formation -- not by a long shot. Any receptor that is present in neurons that constitute a memory circuit can modulate memory formation in principle. Off the top of my head, there is an obvious mechanism by which memory formation might be altered by estrogen receptor activation: by increasing ERK/MAPK activity and thereby increasing CREB phosphorylation and CRE-mediated gene expression. This type of gene expression is known to be required for hippocampal memory formation.

Dune · 06-05-2003, 12:30 AM

tribalbeeyatch-

If that where the case, then memory would flucuate as the monthly cycle moved along and alter significantly during and after menopause.
Is that the case?

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06-04-2003, 01:09 PM	#31
Daleth Regular Member Join Date: May 2003 Location: NYC, 5th floor, on the left Posts: 372	Thanks for the link, scigirl. Damn, it's almost offensive to show the levels changing so slightly and knowing what a big effect it can have. I demand a finer scale on the graph so the changes look much more significant. And none of this is going to help with geriatrics. Dal

06-04-2003, 03:20 PM	#32
Dune Junior Member Join Date: May 2003 Location: Oregon Posts: 65	<quote>The study doesn't state or hazard a guess at which hormone or which combination of them might cause this specialized hijacking of the brain, but like I said, I think it's bunk. <quote> That was more the question I was asking rather than what hormones are involved. I am well versed in the biochemistry of the event, I just can't see how that would relate... So I am agreeing with you as well. <quote> think most women do have the estrogen surge though (normally the estrogen surge induces the LH surge, but not if you are on the pill). I"ll have to investigate this. <quote> estrodiol surge stimulates the LH and FSH surges which stimulate ovulation. Oral contraception (either combo E2/progesterone or progesterone alone) block the LH surge preventing ovulation. <quote>Progesterone is very low during the follicular phase, then goes up a teeny teeny bit during ovulation, then stays up until the luteal phase is over. <quote> I dont know about teeny teeny bit, secretion does go up about 10x..... But essentially correct. But like both of you; im not sure how this would cause an increase in forgetfullness. If that where true, wouldn't women's test scores drop?

06-04-2003, 03:26 PM	#33
tribalbeeyatch Senior Member Join Date: Apr 2001 Location: On the edge Posts: 509	I dunno how credible the study is, but there are plenty of hormone receptors expressed in memory-related areas of the brain.

06-04-2003, 03:33 PM	#34
Dune Junior Member Join Date: May 2003 Location: Oregon Posts: 65	<quote>but there are plenty of hormone receptors expressed in memory-related areas of the brain.<quote> But I dont believe any of them are receptors for the sex hormones.

06-04-2003, 07:17 PM	#38
Dune Junior Member Join Date: May 2003 Location: Oregon Posts: 65	Let me clarify my response. Sex hormone receptors are in the brain, but not involved in memory. Receptors believed to be involved in memory are NMDA and non-NMDA receptors, and estrogen and progesterone are not known ligands for these receptors. I never intended to imply that sex hormones do not have receptors in any part of the brain or even in the hippocampus- this would be silly.

06-04-2003, 08:12 PM	#39
tribalbeeyatch Senior Member Join Date: Apr 2001 Location: On the edge Posts: 509	Dune, glutamate receptors aren't the only ones involved in hippocampal memory formation -- not by a long shot. Any receptor that is present in neurons that constitute a memory circuit can modulate memory formation in principle. Off the top of my head, there is an obvious mechanism by which memory formation might be altered by estrogen receptor activation: by increasing ERK/MAPK activity and thereby increasing CREB phosphorylation and CRE-mediated gene expression. This type of gene expression is known to be required for hippocampal memory formation.

06-05-2003, 12:30 AM	#40
Dune Junior Member Join Date: May 2003 Location: Oregon Posts: 65	tribalbeeyatch- If that where the case, then memory would flucuate as the monthly cycle moved along and alter significantly during and after menopause. Is that the case?

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