Vaginocervical stimulation induces Fos in glutamate neurons in the ventromedial hypothalamus: Attenuation by estrogen and progesterone

Repeated administration of estradiol promotes mechanisms of sexual excitation and inhibition: Glutamate signaling in the ventromedial hypothalamus attenuates excitation

“…Thus to extend on a potential role for to the PAG, it is hypothesized that if AMPA receptor activation within the vlVMH (following VCS) interacts with the PAG to inhibit lordosis and facilitate defensive behaviors, this pathway must be overridden in those females that are repeatedly treated with EB and allowed to copulate. Overall, these findings are important as they further demonstrate that glutamate signaling in the vlVMH via AMPA receptors, is inhibitory to sexual behavior, and induces a behavioral pattern reminiscent of estrous termination [6,15,16,[18][19][20].…”

“…Importantly, the induction of pseudopregnancy (which requires twice daily prolactin surges) depends on repeated and temporally distinct activation of NMDA receptors within the pdMeA, indicating that it plays an important role in the intromission mnemonic within a mating session required for initiating pseudopregnancy/pregnancy [28], and our data suggest that this mnemonic may summate across mating sessions. We know that VCS activates glutamate neurons within the vlVMH [20], and that the vlVMH sends efferents to the pdMeA [1], however it is not known whether the glutamatergic neurons of the vlVMH are the same that project to the pdMeA, but if so, they may play a role in that mnemonic. Thus, an important pathway implicated in the sensitization of sexual behaviors by EB likely occurs through complex interactions between the vlVMH, mPOA and pdMeA, which is possible given the bilateral connections between all these regions [1,3,14,[17][18][19]27].…”

“…The onset of estrous termination is accelerated by the receipt of VCS from penile intromissions or experimenter applied with a glass rod (e.g., [12,30,41]), however if the frequency of hormone priming is increased from every 28 days to every 14 days to every 4 days, the inhibitory effect of VCS becomes progressively less robust [41]. The administration of VCS also activates Fos, a marker of neuronal activation, within numerous sexually relevant brain regions [40], including glutamate neurons of the vlVMH [20], but the number of Fos-labeled glutamate cells in the vlVMH following VCS is reduced by EB + P priming compared to oil treated controls [20]. Importantly, the ability of VCS to induce estrous termination is prevented by blocking the AMPA/kainate glutamate receptor subtype [16].…”

Neurobiology of Sexual Desire

“…In a series of studies, Pfaus and colleagues examined the role of glutamate in the ventromedial nucleus of the hypothalamus and found the inhibitory role of the glutamate receptors, both appetitive and consumatory, at the ventromedial nucleus of the hypothalamus (Georgescu and Pfaus, 2006 a&b;Georgescu et al, 2009Georgescu et al, , 2012. Kow and colleagues also reported inhibitory effects of glutamate in the ventromedial nucleus of the hypothalamus but noted that inhibitory neural mechanisms were different from the facilitatory mechanisms (Kow et al, 1985).…”

A presença do hormônio concentrador de melanina no ovário no ciclo reprodutivo de ratas<i> Sprague-Dawley</i>.

“…Por outro lado, estrógeno e progesterona podem agir indiretamente no VMH através da inibição de sistemas inibitórios da excitação sexual: estudos com infusões de glutamato ou mesmo do agonista de seu receptor no VMH, causam inibição das fases apetitiva e consumatória do comportamento sexual. Essa inibição porém é revertida em ratas ovariectomizadas quando tratadas com esteroides, comparadas às ratas sem suplementação hormonal (Georgescu et al, 2009). …”