Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Sep 2003
Behavioral effects and anatomic correlates after brain injury: a progesterone dose-response study.
Evidence suggests that progesterone enhances functional recovery in rats after medial frontal cortical contusions; however, a high dose of progesterone exacerbates tissue loss in a stroke model when administered chronically (7-10 days) prior to injury [Stroke 31 (2000) 1173)]. This study attempts to determine progesterone's dose-response effects on behavioral performance and GABA-A receptor expression following a cortical contusion. Male rats received injections of 0, 8, 16, or 32 mg/kg progesterone in 22.5% 2-hydroxypropyl-beta-cyclodextrin following cortical impact. ⋯ These results suggest that low and moderate doses of progesterone are optimal for facilitating recovery of select behaviors and that postinjury progesterone treatment permits a wider dose range than preinjury treatment. Progesterone did not affect lesion size, but a strong negative correlation was observed between thalamic GABA-A receptor density and water maze performance. Future studies could explore causes for this relationship.
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Pharmacol. Biochem. Behav. · Sep 2003
Comparative StudySex-related differences in the enhancement of morphine antinociception by NMDA receptor antagonists in rats.
The effect of the N-methyl-D-aspartate (NMDA) receptor antagonists dextromethorphan (DEX), ketamine (KET), and MK-801 on morphine (MOR)-induced antinociception has been investigated in male and female rats. DEX (7.5, 15, and 30 mg/kg), KET (0.75, 1.5, and 3 mg/kg), and MK-801 (0.075, 0.15, and 0.3 mg/kg) dose-dependently enhanced MOR-induced (3 mg/kg) analgesia in female rats. DEX and KET enhanced the peak effect, whereas MK-801 increased both magnitude and duration of analgesia. ⋯ However, the interaction was of less magnitude in male compared with female rats. The effects of KET and MK-801 on MOR-induced analgesia were negligible in male rats. A 3-mg/kg dose of MOR given alone produced greater analgesia in male than in female rats, but in the presence of NMDA antagonists, MOR elicited similar analgesic responses in both sexes.