Possible
Explanation of Nausea
(Copyright
2010, James Michael Howard, Fayetteville, Arkansas, U.S.A.)
This is a
possible explanation of nausea in pregnancy that may also explain nausea in
general. A number of ideas have to be combined
to complete my explanation.
It is my
hypothesis that evolution selected DHEA because it optimizes replication and
transcription of DNA. Therefore, I think
this selection was very important in the evolution of mammals: "Hormones
in Mammalian Evolution," Rivista di Biologia / Biology Forum 2001; 94:
177-184.
It is my
hypothesis of 1985 that the "fight or flight mechanism" is based on
the ratio of DHEA to cortisol. That is,
I think DHEA levels determine the amount of motivation an organism brings to a
confrontation and cortisol evolved to counteract the effects of DHEA. If cortisol is high enough, then an organism
avoids the consequences of a confrontation such as loss of blood, infection,
...death. Evolution would quickly select
this mechanism as it would promote future reproduction of more organisms which
/ who avoid a fight than those who do.
This is also
derived from my examination of the adrenal hormone pathways in 1984. It became apparent to me quickly that there
really are mainly two pathways of major amounts of hormone production, that is,
DHEA and cortisol. (“A Theory of the Control of the Ontogeny and Phylogeny of
Homo sapiens by the Interaction of Dehydroepiandrosterone and the Amygdala,”
Copyright 1985, James Michael Howard, Fayetteville, Arkansas, U.S.A. (Registered Copyright Txu220580).)
Cortisol
has been connected with nausea and, in fact, dexamethasone, which is used to
reduce nausea, and reportedly: "an anti-emetic dose of dexamethasone
markedly suppresses plasma cortisol..." (Anaesth Intensive Care. 2010
Jul;38(4):667-70). Marijuanna,
cannabinoids, have been found to reduce nausea.
The reason may be reduction of cortisol.
“Hormonal measurements were performed by radioimmunoassay. Basal
prolactin (11.5 +/- 4.3 ng/ml) and growth hormone (1.5 +/- 0.7 ng/ml) levels
were unchanged after placebo and CBD. In contrast, plasma cortisol levels
decreased significantly during the placebo sessions (basal measurement = 11.0
+/- 3.7 micrograms/dl; 120 min after placebo = 7.1 +/- 3.9 micrograms/dl), in
agreement with the normal circadian rhythm of this hormone.” (Braz J Med Biol
Res 1993; 26: 213-7).
I
suggest all tissues rely on optimal levels of DHEA for optimal growth and
development and maintenance, thereafter.
Therefore, a mother produces DHEA for herself and her fetus until birth,
whereupon the fetus stars producing DHEA which stimulates birth. Therefore, the fetus takes DHEA at the
expense of the mother. In women of lower
DHEA, I suggest this use of DHEA by the fetus increases the mother’s cortisol
to DHEA ratio and triggers nausea.
The
precursor of DHEA is DHEA sulfate (DHEAS).
If DHEAS is high then DHEA is not being produced. As early as 1986, it was found that “In the
last trimester, significantly higher DHEA-S concentrations and lower
testosterone values were found in women who had suffered from nausea and
vomiting in early pregnancy compared to asymptomatic subjects.” (Eur J Obstet
Gynecol Reprod Biol1986 Feb;21(2):87-99).
Subsequently, it was reported that “Maternal levels of
androstenedione and DHEAS associated positively with nausea and vomiting in
week 17. In week 33, testosterone and DHEAS associated positively with nausea
and vomiting, as well as androstenedione. A calculated emesis score associated
positively with increasing average levels of both androstenedione and
testosterone during pregnancy, as well as the free testosterone index.” (Acta
Obstet Gynecol Scand 2003; 82: 225-8).
Other times
of Nausea:
The other phenomena
that produce nausea may also be explained by low DHEA or an increased ratio of
cortisol to DHEA.