Sex differences and estrous cycle variations in amphetamine-elicited rotational behavior

Area of Science:

• Neuroscience
• Pharmacology
• Endocrinology

Background:

• Amphetamine (AMPH) is a psychostimulant affecting dopamine pathways.
• Sex and hormonal fluctuations can influence drug responses.
• Investigating these factors is crucial for understanding neurochemical modulation.

Purpose of the Study:

• To determine sex- and estrous cycle-dependent differences in amphetamine-elicited rotational behavior in rats.
• To measure brain and striatal levels of amphetamine after systemic administration.
• To explore the influence of gonadal steroids on mesostriatal dopamine activity.

Main Methods:

• Systemic administration of amphetamine (1.0-10.0 mg/kg) to unlesioned male and female rats.
• Measurement of whole brain and striatal amphetamine levels.
• Quantification of net rotational behavior across different estrous cycle phases.

Main Results:

• Females exhibited significantly higher brain amphetamine levels than males at all tested doses.
• Even with equivalent brain amphetamine levels, males showed fewer net rotations than females across estrus, diestrus 2, and proestrus.
• Female rats displayed estrous cycle-dependent variations in rotational behavior, with peak activity on the day of estrus.

Conclusions:

• Sex and estrous cycle significantly modulate amphetamine-induced rotational behavior.
• Differences in behavior may stem from gonadal steroid hormone modulation of mesostriatal dopamine activity.
• These findings highlight the importance of hormonal status in psychostimulant-induced neurochemical changes.