Ovariectomy results in variable changes in nociception, mood and depression in adult female rats.
Decline in the ovarian hormones with menopause may influence somatosensory, cognitive, and affective processing. The present study investigated whether hormonal depletion alters the nociceptive, depressive-like and learning behaviors in experimental rats after ovariectomy (OVX), a common method to deplete animals of their gonadal hormones. OVX rats developed thermal hyperalgesia in proximal and distal tail that was established 2 weeks after OVX and lasted the 7 weeks of the experiment. A robust mechanical allodynia was also occurred at 5 weeks after OVX. In the 5th week after OVX, dilute formalin (5%)-induced nociceptive responses (such as elevating and licking or biting) during the second phase were significantly increased as compared to intact and sham-OVX females. However, chronic constriction injury (CCI) of the sciatic nerve-induced mechanical allodynia did not differ as hormonal status (e.g. OVX and ovarian intact). Using formalin-induced conditioned place avoidance (F-CPA), which is believed to reflect the pain-related negative emotion, we further found that OVX significantly attenuated F-CPA scores but did not alter electric foot-shock-induced CPA (S-CPA). In the open field and forced swimming test, there was an increase in depressive-like behaviors in OVX rats. There was no detectable impairment of spatial performance by Morris water maze task in OVX rats up to 5 weeks after surgery. Estrogen replacement retrieved OVX-induced nociceptive hypersensitivity and depressive-like behaviors. This is the first study to investigate the impacts of ovarian removal on nociceptive perception, negative emotion, depressive-like behaviors and spatial learning in adult female rats in a uniform and standard way.
Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
Li-Hong
LH
Li
Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
Zhe-Chen
ZC
Wang
Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, Shanghai Medical Colloge, Fudan University, Shanghai, China.
Jin
J
Yu
Institute of Neurobiology, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
Yu-Qiu
YQ
Zhang
D000339:Affect / Q000187:drug effects; D000818:Animals; D001522:Behavior, Animal; D003863:Depression / Q000209:etiology* / Q000503:physiopathology; D005239:Fear / Q000187:drug effects; D005260:Female; D005557:Formaldehyde / Q000494:pharmacology; D006930:Hyperalgesia / Q000503:physiopathology / Q000523:psychology; D018782:Maze Learning; D009437:Neuralgia / Q000139:chemically induced / Q000503:physiopathology / Q000523:psychology; D059225:Nociception / Q000187:drug effects; D010052:Ovariectomy / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D005557:Formaldehyde