Title

Cyclic Ovarian Hormone Modulation of Supraspinal Δ9-tetrahydrocannabinol-induced Antinociception and Cannabinoid Receptor Binding in the Female Rat

Document Type

Article

Language

eng

Format of Original

9 p.

Publication Date

9-2014

Publisher

Elsevier

Source Publication

Pharmacology Biochemistry and Behavior

Source ISSN

0091-3057

Original Item ID

doi: 10.1016/j.pbb.2014.06.007

Abstract

Estrous cycle-related fluctuations in delta-9-tetrahydrocannabinol (THC)-induced antinociception have been observed in the rat. The aim of this study was to determine which major ovarian hormone modulates the antinociceptive effects of i.c.v. THC, and whether hormone modulation of THC's behavioral effects could be due to changes in brain cannabinoid receptors (CBr). Vehicle (oil) or hormones (estradiol or progesterone, or both) were administered to female rats on days 3 and 7 post-ovariectomy. On the morning or afternoon of day 8 or day 9, vehicle or THC (100 μg) was administered i.c.v. Paw pressure, tail withdrawal, locomotor activity and catalepsy tests were conducted over a 3-h period. Estradiol (with and without progesterone) enhanced THC-induced paw pressure antinociception only. Ovarian hormones time-dependently modulated CBr in brain structures that mediate antinociception and locomotor activity, but the changes observed in CBr did not parallel changes in behavior. However, the time course of CBr changes must be further elucidated to determine the functional relationship between receptor changes and antinociceptive sensitivity to THC.

Comments

Pharmacology Biochemistry and Behavior, Vol. 124 (September 2014): 269-277. DOI.