Abstract
This study determined the effects of acute treatment with morphine on the expression of the Oprm1, Oprk1, and Oprd1 genes (which encode μ, κ, and δ receptors, respectively) in the striatum, hypothalamus, and periaqueductal gray (PAG) in ovariectomized female rats treated with estrogen. Ovariectomized female rats were divided into five equal groups. Two groups received estrogen (50 µg/kg, 54 h before testing) and saline (ES group) or 3.5 mg/kg morphine (EM group) 2 h before euthanasia. The SS group received saline solution 54 and 2 h before the experiments. The SM group received saline 54 h and 3.5 mg/kg morphine 2 h before the experiments. The W group remained undisturbed. The genes expression were evaluated. Oprm1 and Oprk1 expression were activated, respectively, in the hypothalamus and PAG and in the striatum and PAG by morphine only in estrogen-treated animals. Oprd1 expression in the hypothalamus and PAG was activated by morphine in both estrogen-treated and -nontreated animals. The Oprm1 and Oprk1 gene response to morphine might depend on estrogen, whereas the Oprd1 gene response to morphine might not depend on estrogen, supporting the hypothesis of a functional role for ovarian hormones in opioid receptor-mediated functional adaptations in the female brain.
Highlights
Female gonadal hormones have an important impact on many brain functions and behaviors related to reproduction and neurotransmission in some brain sites
The present study evaluated the modulatory role of morphine and steroid hormones in ovariectomized (OVX) virgin rats with regard to Oprm1, Oprk1, and Oprd1 gene expression in the periaqueductal gray (PAG), striatum, and hypothalamus because these regions are involved in the control of motivated, motor, and reproductive behaviors
The present study investigated the role of acute estrogen administration on opioid gene expression in the striatum, hypothalamus, and PAG and the effects of acute morphine treatment
Summary
Female gonadal hormones have an important impact on many brain functions and behaviors related to reproduction and neurotransmission in some brain sites. These pathways exist through direct binding to specific membrane receptors or through an indirect action via genetic mechanisms and differences in gene expression and protein content (Wilson and Westberry 2009). The regulation of pituitary gonadotropin secretion may result from a complex interaction between a gonadal steroid feedback mechanism and the influence of brain neurotransmitter systems in the hypothalamic–pituitary system, Endogenous opioids can modulate the catecholamine pathway, inhibit catecholamine release during times of stress, and inhibit gonadotropin secretion (Angelopoulos et al 1995). In regions of the striatum and hypothalamus, they appear to modulate motor and reproductive function, respectively (Hammer et al 1994; Teodorov et al 2006, 2014; Miranda-Paiva et al 2007; Yim et al 2006; Sukikara et al 2006)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
