title: Cyclic estrogenic fluctuation influences synaptic transmission of the medial vestibular nuclei in female rats.
abstract: CONCLUSIONS
  The estrous cycle in female rats influences the basal synaptic responsiveness and plasticity of the medial vestibular nucleus (MVN) neurons through different levels of circulating 17β-estradiol (cE(2)).
  
  
  OBJECTIVE
  The aim of this study was to verify, in the female rat, whether cyclic fluctuations of cE(2) influence long-term synaptic effects induced by high frequency afferent stimulation (HFS) in the MVN, since we found that HFS in the male rat induces fast long-term potentiation (fLTP), which depends on the neural synthesis of E(2) (nE(2)) from testosterone (T).
  
  
  METHODS
  We analyzed the field potential (FP) evoked in the MVN by vestibular afferent stimulation, under basal conditions, and after HFS, in brainstem slices of female rats during high levels (proestrus, PE) and low levels (diestrus, DE) of cE(2). Selective blocking agents of converting T enzymes were used.
  
  
  RESULTS
  Unlike in the male rat, HFS induced three effects: fLTP through T conversion into E(2), and slow LTP (sLTP) and long-term depression (LTD), through T conversion into DHT. The occurrence of these effects depended on the estrous cycle phase: the frequency of fLTP was higher in DE, and those of sLTP and LTD were higher in PE. Conversely, the basal FP was also higher in PE than in DE.
authors.affiliation: Department of Internal Medicine, Section of Human Physiology, University of Perugia, Italy. vitopett@unipg.it
authors.forename: Vito E
authors.initials: VE
authors.lastname: Pettorossi
authors.forename: Adele
authors.initials: A
authors.lastname: Frondaroli
authors.forename: Silvarosa
authors.initials: S
authors.lastname: Grassi
mesh_terms: D058891:5-alpha Reductase Inhibitors; D000818:Animals; D047072:Aromatase Inhibitors; D004031:Diestrus; D004558:Electric Stimulation; D004958:Estradiol / Q000502:physiology*; D005260:Female; D018120:Finasteride; D066298:In Vitro Techniques; D000077289:Letrozole; D009570:Nitriles; D011359:Proestrus; D051381:Rats; D017208:Rats, Wistar; D009435:Synaptic Transmission; D014230:Triazoles; D014726:Vestibular Nuclei / Q000502:physiology*
chemical_list: D058891:5-alpha Reductase Inhibitors; D047072:Aromatase Inhibitors; D009570:Nitriles; D014230:Triazoles; D004958:Estradiol; D018120:Finasteride; D000077289:Letrozole