SSRI treatment decreases prolactin and hyperthermic responses to mCPP

Area of Science:

• Neuropharmacology
• Endocrinology
• Psychopharmacology

Background:

• Selective serotonin reuptake inhibitors (SSRIs) are widely used anxiolytics.
• The 5-HT2C receptor plays a role in neuroendocrine and thermoregulatory functions.
• The long-term effects of SSRIs on 5-HT2C receptor sensitivity are not fully understood.

Purpose of the Study:

• To investigate the impact of chronic paroxetine treatment on neuroendocrine and hyperthermic responses mediated by 5-HT2C receptors.
• To explore the potential desensitization of 5-HT2C receptors following repeated SSRI administration.

Main Methods:

• Seven healthy volunteers received daily paroxetine (30 mg) for three weeks.
• Neuroendocrine (prolactin) and hyperthermic responses were measured after intravenous administration of m-chlorophenylpiperazine (mCPP), a 5-HT2C receptor agonist.
• Responses were compared before and after the paroxetine treatment period.

Main Results:

• Paroxetine treatment significantly attenuated both the prolactin and hyperthermic responses to mCPP.
• The reduction in response suggests a functional decrease in 5-HT2C receptor sensitivity.
• These findings align with animal studies indicating SSRI-induced 5-HT2C receptor desensitization.

Conclusions:

• Repeated SSRI treatment, exemplified by paroxetine, leads to functional desensitization of 5-HT2C receptors in humans.
• This 5-HT2C receptor desensitization may underlie the therapeutic anxiolytic effects of SSRIs.
• The study provides human evidence supporting the role of 5-HT2C receptor modulation in SSRI efficacy.