title: Estrogen and progesterone improve scopolamine-induced impairment of spatial memory.
abstract: This study was conducted to investigate the effects of estrogen and progesterone on spatial memory in ovariectomized female rats, specifically, on memory impaired by the cholinergic antagonist scopolamine. Forty-one female rats were divided into five groups: ovariectomized (OVX), estrogen-treated after ovariectomy (OE), progesterone-treated after ovariectomy (OP), estrogen-progesterone-treated after ovariectomy (OEP), and the sham control group (Control). The animals were trained on an eight-arm radial maze with four arms baited to assess both working and reference memory performances. The OE and OEP groups showed significant improvement in the ability to perform a spatial memory task over the OVX group (P<0.05). Spatial memory in the OP group did not differ from that in the OVX group. After thirty-two trials were conducted and all rats learned the eight-radial maze task, scopolamine hydrobromide (0.2 mg/kg i.p.) was administered prior to retesting. After scopolamine injection, the OVX group showed an increased number of working memory errors, reference memory errors than the other groups (P<0.05). The OE, OEP and OP groups showed significant improvement in spatial impairment induced by scopolamine. These findings suggest progesterone alone or in combination with estrogen, improved scopolamine-induced impairment of working memory and reference memory as effectively as estrogen supplementation.
authors.affiliation: Comprehensive Reproductive Medicine, Graduate School, Tokyo Medical and Dental University, Japan. f.tanabe.gyne@tmd.ac.jp
authors.forename: Fumiko
authors.initials: F
authors.lastname: Tanabe
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Miyasaka
authors.forename: Toshiro
authors.initials: T
authors.lastname: Kubota
authors.forename: Takeshi
authors.initials: T
authors.lastname: Aso
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003692:Delayed-Action Preparations; D004343:Drug Implants; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects; D008569:Memory Disorders / Q000139:chemically induced*; D018727:Muscarinic Antagonists / Q000009:adverse effects*; D010052:Ovariectomy; D011374:Progesterone / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012601:Scopolamine / Q000009:adverse effects*
chemical_list: D003692:Delayed-Action Preparations; D004343:Drug Implants; D004967:Estrogens; D018727:Muscarinic Antagonists; D011374:Progesterone; D012601:Scopolamine