Odor Sensitivity After Intranasal Insulin Application Is Modulated by Gender

Area of Science:

• Neuroscience
• Endocrinology
• Olfactory Research

Background:

• Obesity is a global health issue often linked to eating habits.
• Understanding energy intake and expenditure is crucial for effective interventions.
• Insulin's role in regulating energy intake and its potential impact on olfactory sensitivity for weight management are increasingly recognized.

Purpose of the Study:

• To investigate the effect of intranasal insulin on olfactory sensitivity.
• To explore gender-specific responses to intranasal insulin regarding smell perception.
• To examine the influence of insulin on the perception of specific odors (n-butanol and peanut).

Main Methods:

• A placebo-controlled, double-blind, within-subject design was employed.
• 30 healthy participants received either intranasal insulin (40 IU) or placebo on separate days.
• Olfactory sensitivity tests for n-butanol and peanut were conducted post-administration, with blood parameters also measured.

Main Results:

• Intranasal insulin administration affected insulin, leptin, and cortisol levels but not plasma glucose.
• Olfactory sensitivity to n-butanol was significantly reduced in females but not males after insulin administration compared to placebo.
• Olfactory sensitivity to peanut odor remained unaffected by intranasal insulin in both genders.

Conclusions:

• Central insulin administration differentially affects olfactory sensitivity based on gender.
• Reduced olfactory sensitivity to n-butanol in women after intranasal insulin suggests gender-specific modulation of insulin and leptin signaling.
• These findings highlight the complex interplay between hormones, gender, and sensory perception in regulating body weight and eating behavior.