, 2008). Thus, melanocortin hormone levels predicted the amount of testosterone and other sexual steroids along with concomitant increases (or decreases) in aggression and sexual behavior. Placing darker versus lighter pigmented individuals with adoptive parents of the opposite pigmentation did not modify offspring behavior. Male lions with darker manes remained more aggressive and sexually active than those with lighter manes, and darker feathered barn owls continued to have a stronger immune response to stress than lighter feathered barn owls. It was the biological, not adopting parent who determined coloration in the offspring. The biological

and behavioral responses are a finely regulated balance between neurotransmitters and Natural Product Library hormones at the level of the whole organism. The genes that control that balance occupy a high level in the hierarchical system of the genome. The system is defined anatomically as a collection of central nervous system circuits which include neurons that express peptides and proteins that originate in the arcuate nucleus and the brainstem. Downstream, targets of these melanocortin hormones bind to five melanocortin receptors, each one being associated with different physiological and behavioral functions. selleckchem (For a review of the biochemistry of the melanocortin system, see Fong (2003);

for a review of pharmacological effects, see Roulin and Ducrest (2011).) Further, Roulin and Ducrest (2011) describe the role of the melanocortin system in activating the MC1 receptor induced by the production of brown to black eumelanic pigments. this website Activation of four other melanocortin receptors affected stress response, energy homeostasis, female sexual receptivity and male sexual performance. These were mediated by the production of sexual steroids including

testosterone. Although numerous genes interact to stabilize an organism’s development, the lead role belonged to the genes controlling the functioning of the neural and endocrine systems. However, Ducrest et al. (2008) cautioned, because of genetic mutations, melanin-based coloration may not exhibit these traits consistently across human populations. Pigmentation change in wild silver foxes (Vulpes vulpes) was one outcome of breeding for tameness. It was the Russian geneticist Belyaev (1917–1986) who found that selecting easy-to-handle foxes pulled along with it many features that distinguish domestic animals from their wild forebears including white patches in the fur, droopy ears, a smaller skull, and a faster reproductive cycle ( Trut, 2003 and Trut et al., 1997). Domesticated foxes reached sexual maturity a month earlier (at 7 months) than non-domesticated foxes, and gave birth to litters averaging one pup larger (about six).

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