The role of glucocorticoid and nicotinic acetylcholine receptors in the reward-enhancing effects of nicotine in the ICSS procedure in male and female rats.
Study Goal
The researchers aimed to determine the role of glucocorticoid receptors (GRs) and nicotinic acetylcholine receptors (nAChRs) in the acute rewarding effects of nicotine using an intracranial self-stimulation (ICSS) procedure in rats.
Results Summary
Nicotine enhanced the rewarding effects of ICSS and had stimulant properties, lowering brain reward thresholds and decreasing response latencies in both male and female rats. The GR antagonist mifepristone did not affect nicotine's reward-enhancing effects but increased response latencies, while the nAChR antagonist mecamylamine blocked nicotine's effects, indicating nAChRs mediate nicotine's rewarding effects.
Population
Adult male and female rats with ICSS electrodes implanted in the medial forebrain bundle.
Effective Dosage
Not specified
Duration
Not specified
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
nicotine | decrease | brain reward thresholds | adult male and female rats | - | lowered | #1 |
nicotine | decrease | response latencies | adult male and female rats | - | decreased | #2 |
the GR antagonist mifepristone | no change | the reward-enhancing effects of nicotine | adult male and female rats | - | did not affect | #3 |
the GR antagonist mifepristone | increase | response latencies | adult male and female rats | - | increased | #4 |
mecamylamine | decrease | the nicotine-induced decrease in brain reward thresholds | adult male and female rats | - | prevented | #5 |
mecamylamine | decrease | the nicotine-induced decrease in response latencies | adult male and female rats | - | prevented | #6 |
mecamylamine | no change | the brain reward thresholds of the control rats | adult male and female rats | - | did not affect | #7 |
mecamylamine | no change | the response latencies of the control rats | adult male and female rats | - | did not affect | #8 |
Tobacco use disorder is a chronic disorder that affects more than one billion people worldwide and causes the death of millions each year. The rewarding properties of nicotine are critical for the initiation of smoking. Previous research has shown that the activation of glucocorticoid receptors (GRs) plays a role in nicotine self-administration in rats. However, the role of GRs in the acute rewarding effects of nicotine are unknown. In this study, we investigated the effects of the GR antagonist mifepristone and the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine on the reward-enhancing effects of nicotine using the intracranial self-stimulation (ICSS) procedure in adult male and female rats. The rats were prepared with ICSS electrodes in the medial forebrain bundle and then trained on the ICSS procedure. Nicotine lowered the brain reward thresholds and decreased response latencies similarly in male and female rats. These findings suggest that nicotine enhances the rewarding effects of ICSS and has stimulant properties. Treatment with the GR antagonist mifepristone did not affect the reward-enhancing effects of nicotine but increased response latencies, suggesting a sedative effect. Mecamylamine prevented the nicotine-induced decrease in brain reward thresholds and response latencies, but did not affect the brain reward thresholds or response latencies of the control rats. These findings suggest that the rewarding effects of nicotine are mediated via the activation of nAChRs, and that the activation of GRs does not contribute to the acute rewarding effects of nicotine. These studies enhance our understanding of the neurobiological mechanisms underlying tobacco use disorder.