Role of hypothalamus nociceptin/orphanin FQ in pre-ovulatory luteinizing hormone surge of estrogen and progesterone-primed, ovariectomized rats

An, Xiaofei; Yu, Jiangyi; Feng, Yi; Chen, Bo-Ying; Zhang, Sulin

doi:10.1111/j.1745-7254.2007.00587.x

Cited by 11 publications

(9 citation statements)

References 24 publications

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“…OFQ/N also diminishes the magnitude of the LH surge seen in estradiol-primed, progesterone-treated rats. Moreover, OFQ/N expression in the ARH is decreased during proestrus [72], at a time when estradiol levels are at their highest, which parallels the estrogenic disruption in ORL1 receptor-mediated signaling that we observed in the present study.…”

Section: Discussionsupporting

confidence: 75%

Estradiol Negatively Modulates the Pleiotropic Actions of Orphanin FQ/Nociceptin at Proopiomelanocortin Synapses

et al. 2013

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Orphanin FQ/nociceptin (OFQ/N) inhibits the activity of proopiomelanocortin (POMC) neurons located in the hypothalamic arcuate nucleus (ARH) that regulate female sexual behavior and energy balance. We tested the hypothesis that estradiol modulates the ability of OFQ/N to pre- and postsynaptically decrease the excitability of these cells. To this end, whole-cell patch-clamp recordings were performed in hypothalamic slices prepared from ovariectomized rats, including some that were injected with the retrograde tracer Fluorogold in the medial preoptic nucleus (MPN) to label the POMC neurons regulating sexual receptivity. OFQ/N (1 µM) evoked a robust outward current in ARH neurons from vehicle-treated animals that was blocked by the opioid receptor-like (ORL)1 receptor antagonist UFP-101 (100 nM) and the G protein-gated, inwardly rectifying K⁺ (GIRK-1) channel blocker tertiapin (10 nM). OFQ/N also produced a decrease in the frequency of glutamatergic, miniature excitatory postsynaptic currents (mEPSCs), which was also antagonized by UFP-101. Estradiol benzoate (2 µg) increased basal mEPSC frequency and markedly diminished both the OFQ/N-induced activation of postsynaptic GIRK-1 channel currents and the presynaptic inhibition of glutamatergic neurotransmission. These effects were observed in identified POMC neurons, including eight that projected to the MPN. Taken together, these data reveal that estradiol attenuates the pleiotropic inhibitory actions of OFQ/N on POMC neurons: presynaptically through reducing the OFQ/N inhibition of glutamate release and postsynaptically by reducing ORL1 signaling through GIRK channels. As such, they impart critical insight into a mechanism for estradiol to increase the activity of POMC neurons that inhibit sexual receptivity.

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Section: Discussionsupporting

confidence: 75%

Estradiol Negatively Modulates the Pleiotropic Actions of Orphanin FQ/Nociceptin at Proopiomelanocortin Synapses

et al. 2013

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“…What appear to be conflicting results on the ovarian steroid regulation of POMC expression are more congruent when considered in context with the steroid priming paradigm, and its effects on inducing sexual receptivity and the LH surge. In general, β-END release inhibits both lordosis and LH release [44]. We observed 24 hours after EB priming that POMC expression is increased in OVX rats.…”

Section: Discussionmentioning

confidence: 88%

“…Gonadotropin releasing hormone (GnRH) feedback loops are also modulated by classical endogenous opioid peptides and the OFQ/N-ORL-1 system [43, 44, 68–78]. In vitro, OFQ/N inhibits GnRH release from hypothalamic and mediobasal hypothalamic sections from OVX rats [74, 79].…”

Section: Discussionmentioning

confidence: 99%

Estradiol Upregulates Progesterone Receptor and Orphanin FQ Colocalization in Arcuate Nucleus Neurons and Opioid Receptor-Like Receptor-1 Expression in Proopiomelanocortin Neurons That Project to the Medial Preoptic Nucleus in the Female Rat

Sanathara

Moreas²,

Mahavongtrakul³

et al. 2014

Neuroendocrinology

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Background: Ovarian steroids regulate sexual receptivity in the female rat by acting on neurons that converge on proopiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (ARH) that project to the medial preoptic nucleus (MPN). Estradiol rapidly activates these neurons to release β-endorphin that activates MPN μ-opioid receptors (MOP) to inhibit lordosis. Lordosis is facilitated by the subsequent action of progesterone that deactivates the estradiol-induced MPN MOP activation. Orphanin FQ (OFQ/N; also known as nociceptin) infusions into the ARH, like progesterone, deactivate MPN MOP and facilitate lordosis in estradiol-primed rats. OFQ/N reduces the activity of ARH β-endorphin neurons through post- and presynaptic mechanisms via its cognate receptor, ORL-1. Methods: We tested the hypotheses that progesterone receptors (PR) are expressed in ARH OFQ/N neurons by immunohistochemistry and ORL-1 is expressed in POMC neurons that project to the MPN by combining Fluoro-Gold injection into the MPN and double-label fluorescent in situ hybridization (FISH). We also hypothesized that estradiol increases coexpression of PR-OFQ/N and ORL-1-POMC in ARH neurons of ovariectomized rats. Results: The number of PR- and OFQ/N-immunopositive ARH neurons was increased as was their colocalization by estradiol treatment. FISH for ORL-1 and POMC mRNA revealed a subpopulation of ARH neurons that was triple labeled, indicating these neurons project to the MPN and coexpress ORL-1 and POMC mRNA. Estradiol was shown to upregulate ORL-1 and POMC expression in MPN-projecting ARH neurons. Conclusion: Estradiol upregulates the ARH OFQ/N-ORL-1 system projecting to the MPN that regulates lordosis.

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“…Central administration of OFQ was indicated to hold an inhibitory effect on the LH surge of estrogen and progesterone primed ovariectomized rats (EBP-primed OVX rats) [20] . In addition, the mRNA expression of OFQ and the ORL1 receptor in the POA and VMH were regulated by estrogen and progesterone in cyclic rats [17] .…”

Section: Discussionmentioning

confidence: 99%

Central administration of Orphanin FQ inhibits GnRH secretion by ORL1 receptor in the median eminence of freely moving ovariectomized rats

Feng

et al. 2009

Neurosci. Bull.

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Role of hypothalamus nociceptin/orphanin FQ in pre-ovulatory luteinizing hormone surge of estrogen and progesterone-primed, ovariectomized rats

Cited by 11 publications

References 24 publications

Estradiol Negatively Modulates the Pleiotropic Actions of Orphanin FQ/Nociceptin at Proopiomelanocortin Synapses

Estradiol Negatively Modulates the Pleiotropic Actions of Orphanin FQ/Nociceptin at Proopiomelanocortin Synapses

Estradiol Upregulates Progesterone Receptor and Orphanin FQ Colocalization in Arcuate Nucleus Neurons and Opioid Receptor-Like Receptor-1 Expression in Proopiomelanocortin Neurons That Project to the Medial Preoptic Nucleus in the Female Rat

Central administration of Orphanin FQ inhibits GnRH secretion by ORL1 receptor in the median eminence of freely moving ovariectomized rats

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