cron-web.org

[A1CR]

[Posted on behalf of MR; 2001-09-03]

CRONie_SL wrote:

> CR seems to exten lifespan, and age-related disorders and diseases, in
> essnetially ALL EUKARYOCYTES -- that's all living creatures that have
> nuclii in their cells (almost everything, except bacteria, archae, and a
> few more obscure, extremely primitive, groups).
>
> Steroid hormones eist ONLY IN VERTEBRATES (and a very predecessors, such
> as lampreys) -- a group that appeared MUCH more recently than EUKARYOCYTES.
>
> Conclusions:
>
> (1) Whatever the benefits of CR, they're not caused by steroid hormones.

That doesn't follow. SOME CR bennies v clearly ARE caused by changes in
steroid hormones: replacing estrogen negates the CR reduction in breast
cancer (1-3), & the role of cortisol in CR bennies has been documented
as well (4-7). It does v. strongly suggest, hhowever, that the CR effect
per se is either not ULTIMATELY dependent on hormone reduction, or can
be achieved via other mechanisms. Thus:
>
> (3) There's something more fundamental than just hormones in the
> aging process. Reason: Non-vertebrates -- such as insects, molluscs,
> etc, etc. etc -- age -- although they don't have steroid hormones.

But still, mammalian aging and age-related disease are linked to hormones,
and accordingly changes in same do mediate some CR bennies in mammals.

-MR

1: Sylvester PW, Aylsworth CF, Meites J.
Relationship of hormones to inhibition of mammary tumor development by
underfeeding during the "critical period" after carcinogen administration.
Cancer Res. 1981 Apr;41(4):1384-8.
PMID: 6783295 [PubMed - indexed for MEDLINE]

2: Leung FC, Alysworth CF, Meites J.
Counteraction of underfeeding-induced inhibition of mammary tumor growth
in rats
by prolactin and estrogen administration.
Proc Soc Exp Biol Med. 1983 May;173(1):159-63.
PMID: 6856617 [PubMed - indexed for MEDLINE]

3: Sylvester PW, Aylsworth CF, Van Vugt DA, Meites J.
Influence of underfeeding during the "critical period" or thereafter on
carcinogen-induced mammary tumors in rats.
Cancer Res. 1982 Dec;42(12):4943-7.
PMID: 6814746

4. Birt DF, Yaktine A, Duysen E.
Glucocorticoid mediation of dietary energy restriction inhibition of
mouse skin
carcinogenesis.
J Nutr. 1999 Feb;129(2S Suppl):571S-574S. Review.
PMID: 10064335

5. Pashko LL, Schwartz AG.
Reversal of food restriction-induced inhibition of mouse skin tumor
promotion by adrenalectomy.
Carcinogenesis. 1992 Oct;13(10):1925-8.
PMID: 1423856

6. Frame LT, Hart RW, Leakey JE.
Caloric restriction as a mechanism mediating resistance to environmental
disease.
Environ Health Perspect. 1998 Feb;106 Suppl 1:313-24. Review.
PMID: 9539025
http://www.lowdose.org/pubs/ehp/members/framefull.html

7. Zhu Z, Jiang W, Thompson HJ.
Effect of corticosterone administration on mammary gland development and p27
expression and their relationship to the effects of energy restriction on
mammary carcinogenesis.
Carcinogenesis. 1998 Dec;19(12):2101-6.
PMID: 9886563