siRNA silencing of estrogen receptor-α expression specifically in medial preoptic area neurons abolishes maternal care in female mice

Abstract

The medial preoptic area has been shown to be intricately involved in many behaviors, including locomotion, sexual behavior, maternal care, and aggression. The gene encoding estrogen receptor-α (ERα) protein is expressed in preoptic area neurons, and a very dense immunoreactive field of ERα is found in the preoptic region. ERα knockout animals show deficits in maternal care and sexual behavior and fail to exhibit increases in these behaviors in response to systemic estradiol treatment. In the present study, we used viralvector mediated RNA interference to silence ERα expression specifically in the preoptic area of female mice and measured a variety of behaviors, including social and sexual aggression, maternal care, and arousal activity. Suppression of ERα in the preoptic area almost completely abolished maternal care, significantly increasing the latency to pup retrieval and significantly reducing the time the moms spent nursing and licking the pups. Strikingly, maternal aggression toward a male intruder was not different between control and preoptic ERα-silenced mice, demonstrating the remarkably specific role of ERα in these neurons. Reduction of ERα expression in preoptic neurons significantly decreased sexual behavior in female mice and increased aggression toward both sexual partners and male intruders in a seminatural environment. Estrogen-dependent increases in arousal, measured by home cage activity, were not mediated by ERα expression in the preoptic neurons we targeted, as ERα-suppressed mice had increases similar to control mice. Thus, we have established that a specific gene in a specific group of neurons is required for a crucially important natural behavior.ating back to the 1970s, the preoptic region has been implicated in a variety of complex, natural, biologically crucial behaviors, ranging from sexual behavior to locomotion to maternal care. These roles for the preoptic region were first demonstrated using lesion studies; for instance, radiofrequency, electrolytic, and cytotoxic lesions of the medial preoptic area (MPA) were shown to disrupt many components of maternal care (1-6). Likewise, electrolytic lesions (7-9), chemical lesions (9-11), or knife-cuts disrupting preoptic afferents (12,13) all severely impair or abolish male sexual behavior, whereas electrical stimulation of this region enhances male copulatory behaviors (14). Additionally, c-Fos expression, a marker of neuronal activation, is significantly increased in the preoptic region following copulatory behaviors (15). With respect to locomotor activity, there is ample evidence demonstrating that electrical or chemical stimulation of preoptic neurons enhances locomotor activity in rats (16)(17)(18)(19).Given the importance of the preoptic region in mediating these complex biologically relevant hormone-dependent behaviors, the next step was to establish the cytochemical make-up of these populations of neurons. Before immunocytochemical techniques were routinely used, placement of hormone extracts was used to delineate the hormone and...

Nitric Oxide and Serotonin Interactions in Aggression

“…Recently, this technique was used to silence estrogen receptoralpha (ERa) expression in the preoptic area of female mice, given the role of this brain region in maternal care and aggression. Suppression of ERa strongly inhibited maternal care, but had no effect on maternal aggression toward a male intruder (Ribeiro et al 2012). This study is a good example of how RNAi can be a higher resolution technique for studying aggressive behavior.…”

Insights into Rapid Modulation of Neuroplasticity by Brain Estrogens

“…Region-and cell-specific ER knockout mice were used previously to understand estrogen's role in reproduction and neuroprotection (Dupont et al, 2000;Spence et al, 2011), demonstrating the feasibility of such animal models. Another approach that has recently been employed to examine the role of ERa in sexual and aggressive behavior has been to knock down protein expression using virally encoded si-or sh-RNA interference (RNAi) constructs in a brain-specific manner (Ribeiro et al, 2012;Sano et al, 2013). Such approaches, when combined with cell-specific promoters, would potentially enable examination of ER function in both a site-and cell-specific manner.…”

Neonatal exposure to 17β-estradiol down-regulates the expression of synaptogenesis related genes in selected brain regions of adult female rats

“…Estrogen sensitivity is critical for maternal behavior and its action is predominantly mediated by the two nuclear estrogen receptor subtypes (ER-α and ER-β) and they are expressed in a sex-specific manner [25,28]. ER-α has been shown to be involved in female maternal care and regulating anxiety and fear [13,31]. In the present study, we observed down-regulation of ER-α in POA of estradiol administered female rat which indicates that E2 induces important irreversible changes in terms of compromised feminine behavior as well as maternal care and also establishes defeminization during the adult stage.…”