Release of orphanin FQ/nociceptin in the medial preoptic nucleus and ventromedial nucleus of the hypothalamus facilitates lordosis

• Published in: Hormones and behavior Vol. 51; no. 3; pp. 406 - 412
• Main Authors: Sinchak, Kevin, Dewing, Phoebe, Cook, Misty, Micevych, Paul
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-03-2007; Elsevier; Elsevier BV
• Subjects: Animal behavior; Animal reproduction; Animals; Antibodies, Monoclonal - pharmacology; Behavioral psychophysiology; Biological and medical sciences; Diseases of the osteoarticular system; Diseases of the spine; Endocrinology; Estradiol - analogs & derivatives; Estradiol - pharmacology; Estrogen; Female; Fundamental and applied biological sciences. Psychology; Gene expression; Hormones and behavior; Lordosis; Male; Medical sciences; Models, Biological; Nociceptin; NOP; OFQ; Opioid Peptides - antagonists & inhibitors; Opioid Peptides - metabolism; Opioid receptor-like receptor; Opioids; ORL-1; Orphanin FQ; Posture; Preoptic Area - metabolism; Progesterone; Progesterone - pharmacology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Long-Evans; Rodents; Sexual Behavior, Animal - drug effects; Ventromedial Hypothalamic Nucleus - metabolism; Orphanin FQ; Nociceptin; ORL-1; Opioids; Opioid receptor-like receptor; Estrogen; Lordosis; OFQ; Progesterone; NOP; Deformation; Central nervous system; Diseases of the osteoarticular system; Opiates; Spine disease; Hypothalamus; Opioid peptide; Encephalon; Progestagen; Release; Ovarian hormone; N/OFQ receptor; Ventromedial nucleus; Preoptic nucleus; Sex steroid hormone
• ISSN: 0018-506X; 1095-6867
• DOI: 10.1016/j.yhbeh.2006.12.008

Opioid regulation of reproduction has been widely studied. However, the role of opioid receptor-like 1 receptor (NOP; also referred to as ORL-1 and OP4) and its endogenous ligand orphanin FQ/nociceptin (OFQ/N) have received less attention despite their extensive distribution throughout nuclei of the limbic–hypothalamic system, a circuit that regulates reproductive behavior in the female rat. Significantly, the expression of both receptor and ligand is regulated in a number of these nuclei by estradiol and progesterone. Activation of NOP in the ventromedial nucleus of the hypothalamus (VMH) of estradiol-primed nonreceptive female rats facilitates lordosis. NOPs are also expressed in the medial preoptic nucleus (MPN), however, their roles in reproductive behavior have not been studied. The present experiments examined the role of NOP in the regulation of lordosis in the MPN and tested whether endogenous OFQ/N in the MPN and VMH mediates reproductive behavior. Activation of NOP by microinfusion of OFQ/N in the MPN facilitated lordosis in estradiol-primed sexually nonreceptive female rats. Passive immunoneutralization of OFQ/N in either the MPN or the VMH reduced lordosis in estradiol-primed females, but had no effect on lordosis in estradiol
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progesterone-primed sexually receptive rats. These studies suggest that OFQ/N has a central role in estradiol-only induced sexual receptivity, and that progesterone appears to involve additional circuits that mediate estradiol
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progesterone sexual receptivity.