Appetite Regulation by Human Chemosignals From Tears and Plasma

Study Overview
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Brief Summary
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Obesity is closely related to metabolic diseases and its prevalence is sharply increasing. However, there is no safe and effective treatment for obesity so far, the investigators need a breakthrough idea to curtail the constant threat of obesity. It has been recently demonstrated that emotional tears of women can modify sexual responses, one of basic instincts, in men. As appetite and food intake is another basic instinct, chemosignals from tears and plasma may modify appetite and eating behavior in humans.

Conditions
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Obesity

Intervention / Treatment
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* Biological: Sniffing emotional tears
* Biological: Sniffing trickled saline
* Biological: Sniffing fasting plasma
* Biological: Sniffing postprandial plasma


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Woman: Negative for HIV, Syphilis (VDRL), and Hepatitis B and C Man: Has a body mass index (BMI) of 18.5 kg/m2 to 27 kg/m2, inclusive. Exclusion Criteria: Woman: Has eyelids inflammation, conjunctivitis, keratitis, lacrimal duct obstruction. Has skin diseases around eyes. Man: Has diabetes mellitus or dyslipidemia on medication. Received gastrointestinal surgery except appendectomy and hemorrhoidectomy.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Tears<br>Emotional tears of female volunteers while watching sad video clips | Biological: Sniffing emotional tears<br>* A band-aid soaked 100μl of emotional tears will be applied just below nostrils.<br>* Other names: Emotional tears;|
| Placebo Comparator: Saline<br>Saline collected after being trickled down women's skin below eyes like tears | Biological: Sniffing trickled saline<br>* A band-aid soaked 100μl of trickled saline will be applied just below nostrils.<br>* Other names: Trickled saline;|
| Placebo Comparator: Fasting<br>Their own overnight fasting plasma of male volunteers | Biological: Sniffing fasting plasma<br>* A band-aid soaked 100μl of own fasting plasma will be applied just below nostrils.<br>* Other names: Fasting plasma;|
| Experimental: Prandial<br>Their own postprandial plasma of male volunteers | Biological: Sniffing postprandial plasma<br>* A band-aid soaked 100μl of own postprandial plasma will be applied just below nostrils.<br>* Other names: Postprandial plasma;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The degree of appetite by visual analogue scale (VAS) and the amount of food intake by standard test meals in male volunteers while sniffing tears, trickled saline (control), and postprandial and fasting plasma in random order. |  | Visual analogue scale (VAS) will be rated 10 minutes after initial sniffing of tears/plasma just before eating standard test meals. The amount of food intake will be measured by weighing the meals before and after eating. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Appetite regulating hormones(ghrelin, GLP-1, PYY), glucose, testosterone. Determination of tears, tickled saline, and plasma. |  | Blood samples for measuring appetite regulating hormones, glucose, testosterone will be collected at -10, 0, and 60 min. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Emotional tears, Postprandial plasma, Chemosignal, Obesity, Appetite, Food intake