Estrogen treatment increases the levels of regulator of G protein signaling-Z1 in the hypothalamic paraventricular nucleus: possible role in desensitization of 5-hydroxytryptamine1A receptors.
Desensitization of post-synaptic serotonin1A (5-HT1A) receptors may underlie the clinical improvement of neuropsychiatric disorders. In the hypothalamic paraventricular nucleus, Galphaz proteins mediate the 5-HT1A receptor-stimulated increases in hormone release. Regulator of G protein signaling-Z1 (RGSZ1) is a GTPase-activating protein selective for Galphaz proteins. RGSZ1 regulates the duration of interaction between Galphaz proteins and effector systems. The present investigation determined the levels of RGSZ1 in the hypothalamic paraventricular nucleus of rats subjected to four different treatment protocols that produce desensitization of 5-HT1A receptors. These protocols include: daily administration of beta estradiol 3-benzoate (estradiol) for 2 days; daily administration of fluoxetine for 3 and 14 days; daily administration of cocaine for 7 or 14 days; and acute administration of (+/-)-1-(2,5 dimethoxy-4-iodophenyl)-2-amino-propane HCl (DOI; a 5-HT2A/2C receptor agonist). Estradiol treatment was the only protocol that increased the levels of RGSZ1 protein in the hypothalamic paraventricular nucleus in a dose-dependent manner (46%-132% over control). Interestingly, previous experiments indicate that only estradiol produces a decreased Emax of 5-HT1A receptor-stimulation of hormone release, whereas fluoxetine, cocaine and DOI produce a shift to the right (increased ED50). Thus, the desensitization of 5-HT1A receptors by estradiol might be attributable to increased levels of RGSZ1 protein. These findings may provide insight into the adaptation of 5-HT1A receptor signaling during pharmacotherapies of mood disorders in women and the well-established gender differences in the vulnerability to depression.
Carrasco
G A
GA
Center for Serotonin Disorder Research and Department of Pharmacology Loyola University of Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA.
Barker
S A
SA
Zhang
Y
Y
Damjanoska
K J
KJ
Sullivan
N R
NR
Garcia
F
F
D'souza
D N
DN
Muma
N A
NA
van De Kar
L D
LD
D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001923:Brain Chemistry / Q000235:genetics; D003042:Cocaine / Q000494:pharmacology; D003866:Depressive Disorder / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D020690:GTPase-Activating Proteins / Q000187:drug effects* / Q000378:metabolism*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects* / Q000378:metabolism; D020710:RGS Proteins / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000187:drug effects* / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D012727:Sex Characteristics; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D003042:Cocaine; D004967:Estrogens; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D020710:RGS Proteins; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D017366:Serotonin Receptor Agonists; D017367:Selective Serotonin Reuptake Inhibitors; C492955:Rgs20 protein, rat