title: Role of the locus coeruleus in the prolactin secretion of female rats.
abstract: Since locus coeruleus (LC) lesion blocks preovulatory prolactin surge, the aim of this study was to determine if this lesion would also block prolactin surges induced by steroids in ovariectomized rats and would modify basal prolactin secretion. To determine the time of the steroid-induced prolactin surges, ovariectomized rats treated with estradiol (OVE) or estradiol and progesterone (OVEP) were cannulated at 08:00 h and blood samples were collected hourly between 14:00 and 18:00 h. Ovariectomized rats treated with oil (OV-Oil) were used as control. Prolactin peaked at 16:00 h in OVE rats and at 15:00 h in OVEP. In a second experiment, male rats, cycling rats, OVE, OVEP, and OV-Oil groups were cannulated at 08:00 h, followed by LC lesion or sham-surgery. Blood samples were withdrawn at times of basal and peak prolactin levels. LC lesion blocked afternoon prolactin surges of OVE, OVEP and proestrus rats. However, the low levels observed at 16:00 h in OV-Oil, diestrus and male rats as well as at 11:00 h in OVE, OVEP, estrus, and proestrus rats were not modified by LC lesion. The high prolactin levels observed on estrus afternoon were dramatically reduced by LC lesion. Data suggest that LC neurons are important for steroid-induced prolactin surge genesis, but not for prolactin basal secretion.
authors.affiliation: Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, CEP 14049-900 Ribeirão Preto, SP, Brazil.
authors.forename: Maristela Oliveira
authors.initials: MO
authors.lastname: Poletini
authors.forename: Raphael Escorsim
authors.initials: RE
authors.lastname: Szawka
authors.forename: Celso Rodrigues
authors.initials: CR
authors.lastname: Franci
authors.forename: Janete A
authors.initials: JA
authors.lastname: Anselmo-Franci
mesh_terms: D000818:Animals; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D008125:Locus Coeruleus / Q000293:injuries / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010052:Ovariectomy; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D011388:Prolactin