Vb. Mahesh et al., DIVERSE MODES OF ACTION OF PROGESTERONE AND ITS METABOLITES, Journal of steroid biochemistry and molecular biology, 56(1-6), 1996, pp. 209-219
Progesterone and its metabolites have a variety of diverse effects in
the brain, uterus, smooth muscle, sperm and the oocyte. The effects in
clude changes in electrophysiological excitability, induction of anest
hesia, regulation of gonadotropin secretion, regulation of estrogen re
ceptors, modulation of uterine contractility and induction of acrosome
reaction and oocyte maturation. The latency of the effects vary from
several seconds to several hours. Thus, it is not surprising that mult
iple mechanisms of action are involved. The classical mechanism of ste
roid hormone action of intracellular receptor binding has been supplem
ented by the possibility of the steroid acting as a transcription fact
or after the binding of the receptor protein to DNA. Other mechanisms
include influence of the steroids on membrane fluidity and acting thro
ugh other cell signalling systems, membrane receptors and GABA(A) rece
ptors. Of particular interest are multiple mechanisms for the same typ
es of action. For example the effect of progesterone on gondadotropin
release is largely exerted via the classical intracellular receptor as
well as membrane receptors, whereas 3 alpha,5 alpha-tetrahydroprogest
erone-induced LH release occurs via the GABA(A) receptor system. The i
nhibition of uterine contractility by progesterone is regulated by pro
gesterone receptors while the action of 3 alpha,5 alpha-tetrahydroprog
esterone on uterine contractility is regulated by GABA(A) receptors. T
he regulation of the differences in the pattern of progesterone effect
s on estrogen receptor dynamics in the anterior pituitary and the uter
us in the same animal are also of considerable interest.