However, traditional evolution theory has a core tenet that excludes the possibility of evolving and retaining an individually adverse organism design, i.e. a design characteristic that reduces the ability of individual organisms to survive or reproduce without any compensating individual benefit. Various theories of aging dating from the 1950s and based on traditional evolution theory enjoy substantial popularity. Therefore. any theorist proposing an adaptive theory of aging must necessarily also propose some adjustment to traditional evolution theory that specifically
addresses the individual benefit issue. This paper describes an adaptive theory of aging
and selleck compound describes how one of the proposed adjustments (evolvability theory) supports adaptive aging. This issue is important because adaptive theories are generally more optimistic learn more regarding prospects for medical intervention in the aging process and also suggest different approaches in achieving such intervention. (C) 2008 Elsevier Ltd. All rights reserved.”
“The present studies aimed to determine whether estradiol (E(2)) modulates the stimulation of cocaine- and amphetamine-regulated transcript (CART) peptide in the mesolimbic and nigrostriatal dopaminergic systems. I.c.v. administration of the CART peptide (55-102, 1 mu g/3 mu l) increased dopamine turnover (3,4-dihydroxyphenylacetic acid, DOPAC) in the nucleus accumbens (NA) and striatum (ST) in ovariectomized (OVX) female Sprague-Dawley rats with E(2)- priming. This stimulation of NA and ST DOPAC contents by CART peptide was found in OVX+E(2) female rats, but not in OVX only female Inulin rats, suggesting E(2) is an important factor in modulating the stimulatory effect of CART in the regulation of NA and ST DOPAC
contents. This stimulation by CART peptide was also restored by treatment with the water-soluble form of E(2), but not by treatment with the membrane-impermeable form of E(2) in OVX female rats, suggesting that E(2) acts through intracellular rather than extracellular mechanisms to modulate the effects of CART peptide. Furthermore, the effects of water-soluble form of E(2) were blocked by E(2) antagonist, tamoxifen, but not by testosterone antagonist, flutamide. Our findings are the first to demonstrate that that E(2) plays a regulatory role in stimulation of CART peptide in mesolimbic and nigrostriatal dopaminergic systems in female rats, and E(2) acts through its own receptor(s) and intracellular mechanisms. (C) 2008 Published by Elsevier Ltd on behalf of IBRO.