title: Protective effect of pregnanolone against lipoperoxidation and free radicals generation induced in hypothalamus of ovariectomized rats submitted to CO2 exposure.
abstract: Several studies support an association between gonadal hormones and oxidative state. This study aimed to determine the consequence of the absence of ovarian hormones on the oxidative status of animals submitted to acute stress induced by CO(2) inhalation. We also evaluated the effect of pregnanolone administration upon the oxidative status in distinct brain structures of ovariectomized (OVX) rats exposed to CO(2). Female rats were divided into intact and OVX and exposed or unexposed to CO(2). Oxidative status was evaluated by 2',7'-dichlorofluorescein (DCF) assay, assessment of malondialdehyde (MDA), as an indicator of lipoperoxidation (through the thiobarbituric acid-reactive substances assay, TBARS), and the total antioxidant reactivity (TAR). Both DCF and TBARS were increased in the hypothalamus of animals submitted to OVX and stress. Nevertheless, free radical production and MDA levels were not affected in either condition alone. In the cerebral cortex, lower MDA levels were observed in OVX animals. Pregnanolone administered to rats submitted to CO(2)+OVX resulted in reduced MDA levels and free radicals production in hypothalamus. We suggest that ovarian hormones may protect the hypothalamus against oxidative stress, particularly when the animals are submitted to challenges. Pregnanolone may protect, at least in part, the hypothalamus of OVX rats from oxidative stress.
authors.affiliation: Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600, 90035-003 Porto Alegre, RS, Brazil.
authors.forename: Martha E
authors.initials: ME
authors.lastname: Prediger
authors.forename: Ionara R
authors.initials: IR
authors.lastname: Siqueira
authors.forename: Giovana D
authors.initials: GD
authors.lastname: Gamaro
authors.forename: Maura S
authors.initials: MS
authors.lastname: Silva
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Netto
authors.forename: Carla
authors.initials: C
authors.lastname: Dalmaz
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D005260:Female; D005609:Free Radicals / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000502:physiology; D018696:Neuroprotective Agents / Q000494:pharmacology; D010052:Ovariectomy; D011280:Pregnanolone / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D005609:Free Radicals; D018696:Neuroprotective Agents; D002245:Carbon Dioxide; D011280:Pregnanolone