In article <31191109 at gate1.pbi.nrc.ca>, klai at pbi.nrc.ca says...
>>>Regarding Transsexualism- Just a query, if female-like BSTc regions
>found in brains of transsexuals, then why would transsexualism persist
>the evolutionary scheme of thing? Would such structural differences
>through time, or vary?
Similar questions have been posed with regard to homosexuality. I posit
that the answers to such questions will come from further study of the
gonadotropin-releasing hormone (GnRH) neuronal system and of GnRH
pulsatility--as it is influenced by social-environmental chemical
stimuli, e.g., pheromones, via the olfactory systems. (Yes, I believe
that humans have a functional vomeronasal organ and thus, perhaps, a
functional accessory olfactory system.)
Given the mammalian model, pheromones appear to activate genes in GnRH
neurosecretory neurons, thus altering GnRH pulsatility, gonadotropin
secretion and steroidogenesis. The primary sex steroid hormones,
estradiol and testosterone are believed to influence apoptosis,
synaptogenesis, and synaptolysis--in effect, altering the neuroanatomical
"size" of certain structures in the brain, as well as connectivity. Thus,
there is little wonder that these (and other steroids) are also linked to
behavior. But behavior may be prenatally predisposed by the development
of the GnRH neuronal system, just as behavior may be altered by
experiences assoiciated with social-environmental chemical stimuli.
Does anyone know of other social environmental stimuli, besides
pheromones, that appear to alter gene expression in GnRH neurosecretory
cells of tissue in the brain--an organ that is part of the organ system,
which is most consistently linked to reproductive sexual behavior? If
not, doesn't it seem likely that the concept of human pheromones may be
used to explain a variety of animal behaviors?