Sex Steroid Receptors Cheat Sheet

This is a cheat sheet I made to understand the role of estrogen and progestin receptors in sexual behavior. If you are studying basic neuroendocrinology, this might be a useful resource.

 

SEX STEROID RECEPTORS

 

Receptor

Experiment

Results in rodents

 

ERa

Estrogen receptor (ER)

Knock-out (KO) ERa gene Completely eliminates hormonal induction of feminine sexual behavior
ERb KO ERb gene §  No apparent effect in ovariectomized (OVX) hormone-injected mice

§  Extends the period of behavioral estrus

§  Enhances receptivity in estrous-cycling mice

  abERKOs

double knockout

§  Infertile

§  Decreased levels of sexual receptivity

 

Receptor

Experiment

Results in rodents

PR-A

Progestin receptor (PR)

PRAKO mice §  Showed minimal progesterone (P) -facilitated lordosis in the presence of males

§  dominant PR-B isoform alone was incapable of mediating the effects of P on sexual behavior

 

§  Essential role in progesterone-facilitated sexual behavior

PR-B PRKBKO §  Improved PR-A-dependent receptivity with experience

§  Lesser role

 

 

  Experiment Result
Dopamine (DA) agonists DA agonist + P antagonists DA facilitates sexual behavior by indirectly activating PRs

(acts on both isoform)

8-Br-cAMP

(PKA activator)

 

8-Br-cAMP

Protein kinase A =cAMP-dependent protein kinase

Primarily mediated via PR-A isoform

Conclusion:

  • Each isoform of PR may be involved in signaling routes leading to facilitation of sexual behavior, but PR-A seems to have the dominant role in most situations, and PR-B involvement seems to depend upon the mode of activation of the receptor.
  • ER down regulates alpha-ER in most neuroanatomical areas
  • Downregulation of PRs leads to estrous termination and the refractory period
  • Progesterone downregulates its own receptors
  • Functional participation of both the isoforms is critical for P-mediated effects on sexual receptivity
  • Thus, both isoforms of PR, probably via heterodimerization, appear to be required in the RU38486 effects on ligand-independent PR-mediated lordosis.

 

Ligand-Independent Activation of PRs

  • DA agonists can also activate PRs== blocked by P antagonists
  • Facilitation by dopaminergic agonists was blocked by progesterone antagonists, antisense oligonucleotides directed at the PR mRNA or in PRKO mice
  • SKF 81297= DA agonist

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s