Treatment with steroid hormones and morphine alters general activity, sexual behavior, and opioid gene expression in female rats

Author(s)

Teodorov, E. ^[1] ; Camarini, R. ^[2] ; Bernardi, M. M. ^[1] ; Felicio, L. F. ^[3]

Affiliation

^[1] Univ Fed ABC, Ctr Matemat Comp & Cognicao, BR-09210971 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Ciencias Biomed, BR-05508 Sao Paulo - Brazil

^[3] Univ Sao Paulo, Fac Med Vet & Zootecnia, BR-05508 Sao Paulo - Brazil

• Document type: Journal article
• Source: Life Sciences; v. 104, n. 1-2, p. 47-54, MAY 28 2014.
• Web of Science Citations: 5

Abstract

Aims: Previous studies have shown that brain opioid peptides exert an inhibitory influence on gonadotropin secretion. Different types of brain opioids, such as beta-endorphin, enkephalin, and dynorphin, exert their actions by binding to specific opioid receptors (i.e., mu, delta, and kappa, respectively). The present study determined the effects of chronic treatment with morphine in female rats with pharmacologically induced estrus on behavior and opioid receptor gene and protein expression in the hypothalamus, striatum, and periaqueductal gray. Main methods: Female ovariectomized rats treated with estrogen + progesterone received 3.5 mg/kg morphine once per day for 6 days. We evaluated general activity, sexual behavior, Oprm1, Oprd1, and Oprk1 gene expression, and mu opioid receptor (MOR), delta opioid receptor (DOR), and kappa opioid receptor (KOR) protein expression in the hypothalamus, striatum, and periaqueductal gray in adult virgin female ovariectomized rats. Key findings: Chronic morphine treatment increased locomotion and grooming behavior, decreased immobility time, decreased sexual behavior, and decreased the lordosis quotient. The molecular biology results showed that morphine treatment increased Oprm1 gene and MOR protein expression in the striatum and decreased KOR protein expression in the hypothalamus in animals that were assessed for general activity. The animals that were evaluated for sexual behavior exhibited an increase in Oprm1 expression in the periaqueductal gray and increase in KOR expression in the striatum. Significance: These results suggest that both opioid system activation and sex hormones alter behavioral and molecular patterns in ovariectomized rats within a relatively short period of time. (C) 2014 Elsevier Inc. All rights reserved. (AU)

• FAPESP's process: 10/19970-1 - Role of steroid hormones on sexual behavior and molecular biology of opioid receptors in different brain regions of female rats treated with opioid agonist
• Grantee: Elizabeth Teodorov
• Support Opportunities: Regular Research Grants