In a message dated 11/5/99 1:02:36 PM Eastern Standard Time,
[EMAIL PROTECTED] writes:
> Subj: Prenatal androgens (was: inner ear question)
> Date: 11/5/99 1:02:36 PM Eastern Standard Time
> From: [EMAIL PROTECTED] (John Serafin)
> Sender: [EMAIL PROTECTED]
> Reply-to: <A HREF="mailto:[EMAIL PROTECTED]">[EMAIL PROTECTED]
tvincent.edu</A> (John Serafin)
> To: [EMAIL PROTECTED] (TIPS-posts)
>
> In addition to the effects of androgens on the inner ear, and effects on
> the
> hypothalamus that I am aware of, are there other reasonably well-documented
> effects of prenatal androgens on biology (besides on the reproductive
system
> itself, of course)?
>
> John
Hi John -
(How are you ?)
Well, it depends on how reasonably well-documented you want the effects to be
!!
1) The first to come to mind is the work of Doreen Kimura using CAH-based
(indirect) evidence to suggest prenatal-based differences in CNS structures
underlying cognitive spatial abilities secondary to androgen exposure. DK's
quote below is from:
Current Opinion in Neurobiology
Vol. 6, No. 2, April 1996
Sex, sexual orientation and sex hormones influence human cognitive function
by D. Kimura
Which can be temporarily accessed for free at:
<A HREF="http://www.biomednet.com/library/fulltext/JNRB.nb6205">Sex, sexual
orientation and sex hormones influence human cognitive function</A>
"The probable influence of early exposure to androgens in organizing adult
spatial ability is supported by additional studies on spatial performance in
girls with congenital adrenal hyperplasia (CAH). Fluctuations in sex hormones
continue to affect cognitive pattern in adulthood, as evidenced by diurnal,
menstrual and seasonal variations."
2) Here's one from Forger & Breedlove. . . looks as though you guys may have
stronger perineal muscles (well, maybe those not involved in childbirth):
Proc Natl Acad Sci U S A 1986 Oct;83(19):7527-31
Sexual dimorphism in human and canine spinal cord: role of early androgen.
Forger NG, Breedlove SM
Onuf's nucleus, located in the sacral spinal cord of dogs, cats, and
primates, innervates perineal muscles involved in copulatory behavior. A
sexual dimorphism in Onuf's nucleus was found in humans and dogs: males have
significantly more motoneurons in this nucleus than do females. Prenatal
androgen treatment of female dogs eliminated the dimorphism. In the
homologous nucleus in rats, a similar effect of androgen has been shown to
involve sparing of motoneurons from cell death. These results establish a
morphological sex difference in a human central nervous system region of
known function; well-studied animal models suggest explanations of the
development of this dimorphism.
3) Perhaps some relevant rhesus monkey data providing support for Kimura's
speculations:
Brain Res 1990 May 14;516(1):122-6
Androgen receptors are differentially distributed between right and left
cerebral hemispheres of the fetal male rhesus monkey.
Sholl SA, Kim KL
Wisconsin Regional Primate Research Center, University of Wisconsin, Madison
53715-1299.
In humans there are apparent sex differences in verbal and spatial abilities
as well as several cortical pathologies. These differences may arise as the
result of prenatal androgen exposure and its effect on the development of the
cerebral cortex. With this in mind, we have examined androgen receptor (AR),
aromatase (AROM) and 5 alpha-reductase (5 alpha R) levels in the cerebral
cortex of Day 70 male and female fetal rhesus monkeys (Macaca mulatta).
Receptor and enzyme levels were evaluated in both right (Rt) and left (Lft)
temporal (TMP) and frontal (FR) lobes of the cerebral cortex. AR levels in
FR-Rt of male subjects were higher than levels in FR-Lft (for each and every
subject, P less than 0.05), while in females, there was no consistent pattern
in the distribution of the receptor between the two sides of FR. In contrast,
AR values in TMP-Lft of male subjects were consistently higher than in TMP-Rt
(P less than 0.05). As with the FR, females exhibited no consistent pattern
in the distribution of AR between the two TMP sides. AROM and 5 alpha R
levels were similar, regardless of sex, between both sides of the two
cortical lobes indicating that the AR distribution pattern is not a general
biochemical phenomenon. The differential cortical distribution of AR in fetal
males versus females lends support to the hypothesis that prenatal androgens
from the fetal testes may effect the differentiation of sexually dimorphic,
side-specific cortical activity.
Any others out there ??
Trying hard not to be distracted away from a run-away schedule, but
desperately needing a break from it . . . .
Sandra Nagel Randall
SVSU, MI
Athabasca U, Alberta
