Related Experiment Video
Updated: Sep 23, 2026
A General Method for Evaluating Deep Brain Stimulation Effects on Intravenous Methamphetamine Self-Administration
Published on: January 22, 2016
Facilitation of ejaculation after methamphetamine administration in paradoxical sleep deprived rats
Monica Levy Andersen1, Magda Bignotto, Sergio Tufik
1Department of Psychobiology, Universidade Federal de São Paulo, Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, SP, Brazil. mandersen@sti.com.br
Abstract:
This study investigated the effects of methamphetamine (MA) on genital reflexes in paradoxical sleep deprived (PSD) rats. Different doses of MA (0, 4, 16 and 64 mg/kg) were acutely given after PSD or the equivalent time to control animals. We observed enhancement of spontaneous ejaculation in PSD rats with larger doses of MA, the highest of which induced ejaculation in 100% of the PSD rats. This was significantly higher than the 30% in the control. Although testosterone exerts motivational effects on male sexual behavior, our data shows that testosterone levels were lower after the PSD period in saline and in the 64 mg/kg MA groups, which present ejaculation at different rates (20% and 100%, respectively). Progesterone levels were significantly higher in PSD-saline in relation to control group and in the 16 and 64 mg/kg of MA groups compared to the other doses. Since PSD induces dopaminergic alterations and dopamine (DA) has a key role in male sexual behavior, plasma DA was also measured. The DA concentration was enhanced in all PSD groups compared with their control group. The mechanism that activates steroid hormones may represent an important physiological effect through which neurotransmitters can affect behavioral events. These data show that MA facilitates ejaculation in PSD rats, however, further studies need to be carried out in order to clarify the hormonal-neurochemical mechanisms involved.
Insights
Methamphetamine (MA) enhances ejaculation in paradoxical sleep-deprived (PSD) rats, even with reduced testosterone. Dopamine levels increased in PSD rats, suggesting a complex neurochemical pathway influencing sexual reflexes.
Area of Science:
- Neuroscience
- Reproductive Biology
- Pharmacology
Background:
- Paradoxical sleep deprivation (PSD) is known to induce neurochemical alterations.
- Dopamine (DA) plays a crucial role in regulating male sexual behavior.
- The interplay between sleep deprivation, neurotransmitters, and sexual function requires further investigation.
Purpose of the Study:
- To investigate the effects of acute methamphetamine (MA) administration on genital reflexes in PSD rats.
- To examine the influence of MA on hormonal profiles (testosterone, progesterone) and plasma dopamine levels in PSD rats.
- To elucidate the potential neurochemical mechanisms underlying MA-induced changes in sexual behavior under sleep deprivation.
Main Methods:
- Rats were subjected to paradoxical sleep deprivation (PSD) or equivalent control conditions.
- Acute administration of varying doses of methamphetamine (MA) (0, 4, 16, 64 mg/kg) or saline.
- Measurement of spontaneous ejaculation, plasma testosterone, progesterone, and dopamine (DA) levels.
Main Results:
- Methamphetamine significantly enhanced spontaneous ejaculation in PSD rats, with 100% induction at the highest dose, compared to 30% in controls.
- Testosterone levels were lower in PSD rats, irrespective of MA administration, while progesterone levels were elevated in PSD-saline and higher MA dose groups.
- Plasma dopamine concentrations were significantly increased in all PSD groups compared to their respective controls.
Conclusions:
- Methamphetamine facilitates ejaculation in paradoxical sleep-deprived rats, suggesting a potent effect on sexual reflexes.
- The observed effects may involve complex interactions between dopamine, steroid hormones, and sleep deprivation.
- Further research is necessary to fully clarify the hormonal and neurochemical mechanisms mediating these behavioral changes.
