Journal article
Dose- and time-dependent estradiol modulation of morphine antinociception in adult female rats
European journal of pain, Vol.12(4), pp.472-479
2008
Handle:
https://hdl.handle.net/2376/110884
PMID: 17869144
Abstract
To clarify the activational role of ovarian hormones on pain and analgesia, the present study determined whether estradiol (E2) modulation of nociception and morphine antinociception in adult female rats depends on (1) the dose of E2 and (2) the interval between E2 treatment and nociceptive testing. Female rats were ovariectomized (OvX) and either oil vehicle (0), or E2 (0.25, 2.5 or 25
μg/0.1
ml vehicle) was injected s.c. two consecutive days of every four days for five cycles before testing. Either 4, 24, 48 or 96
h after the last injection, nociception was evaluated on the 50
°C hotplate and warm water tail withdrawal tests before and after escalating doses of s.c. morphine. Lordosis behavior and uterine weight were assessed in other rats at the same E2 doses and time points. E2 significantly lengthened latency to respond on the hotplate test at 24
h after the last injection, but had no significant effect on tail withdrawal latencies. The lower doses of E2 significantly increased morphine antinociceptive potency at 4–24
h on one or both tests, but the intermediate E2 dose significantly
decreased morphine potency at 48
h on the hotplate test. Thus, E2 modulation of morphine antinociception in the adult female rat is bidirectional, and occurs at E2 doses producing cyclic changes in sexual behavior, uterine weight and vaginal cytology that are similar to those observed in gonadally intact, cycling females.
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Details
- Title
- Dose- and time-dependent estradiol modulation of morphine antinociception in adult female rats
- Creators
- Rebecca M Craft - Departments of Psychology, Washington State University, Pullman, WA 99164-4820, USACatherine Ulibarri - Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA 99164, USAMichael D Leitl - Departments of Psychology, Washington State University, Pullman, WA 99164-4820, USAJean E Sumner - Departments of Psychology, Washington State University, Pullman, WA 99164-4820, USA
- Publication Details
- European journal of pain, Vol.12(4), pp.472-479
- Academic Unit
- Psychology, Department of; Integrative Physiology and Neuroscience, Department of
- Publisher
- Elsevier Ltd
- Identifiers
- 99900547235101842
- Language
- English
- Resource Type
- Journal article