Effects of Ghrelin Administration on Motivation

December 15, 2025 updated by: University Hospital Tuebingen

The Effects of Ghrelin Administration on Motivation and Resting Energy Expenditure

Everyday humans are confronted with a plethora of rewards competing for their attention. Nevertheless, to obtain a goal or reward, humans often need to invest effort. When humans are confronted with the challenge to integrate costs of action such as the effort of walking to one's favorite lunch place with its anticipated benefits (i.e., eating one's favorite meal), accumulating evidence suggest that humans might "go with the gut". Ghrelin is a stomach-derived hormone and the only known circulating peptide that stimulates appetite. At the same time, patients with major depressive disorder report deficits in motivated behavior which are oftentimes accompanied by changes in appetite and weight. Based on a wealth of accruing evidence from animal studies, the investigators suggest that the gut acts as an important arbitrator in effort allocation by signaling the energy level of the body. Within this physiological framework, ghrelin is thought to signal a short-term energy deficit to increase reward responsivity and willingness to work for reward as compensatory (allostatic) means. Here, the investigators propose to conduct a follow-up study (to NCT05318924) with subcutaneous administration of ghrelin vs. saline in patients with major depressive disorder and healthy control participants. During each visit, participants will receive a subcutaneous administration of either ghrelin or saline and perform an effort allocation task where they have to exert physical effort to obtain food and monetary rewards. The investigators hypothesize that ghrelin will increase the motivation to exert effort for rewards. The goal of this follow-up study is to test that the motivational effects of ghrelin are similar in patients with depression and healthy control participants. Furthermore, participants resting energy expenditure will be estimated before and after the administration. In line with a role of ghrelin as an energy deficit signal, the investigators expect ghrelin to decrease energy expenditure. During each visit, participants will answer questions about their current mood and physiological state. The investigators hypothesize that ghrelin increases mood state and hunger while decreasing satiety.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
24

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Germany
    • Baden-Wurttemberg
      • Tübingen, Baden-Wurttemberg, Germany, 72076
        • Department of Psychiatry & Psychotherapy, University of Tübingen

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

* Must have participated in the behavioral study arm of NCT05120336

Exclusion Criteria:

  • participation in the neuroimaging part of NCT05120336
  • breastfeeding
  • pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Major depressive disorder
Patients with major depressive disorder will receive a subcutaneous injection of ghrelin (experimental) on one day and saline (placebo) on another day (order randomised; double-blind cross-over design).
Drug: Ghrelin
Participants in this arm will receive a subcutaneous injection of acyl-ghrelin as the active condition.
Other Names:
  • Acyl-ghrelin
Drug: Saline
Participants in this arm will receive a subcutaneous injection of saline as placebo control condition.
Other Names:
  • Placebo
Experimental: Healthy control participants
Healthy control participants will receive a subcutaneous injection of ghrelin (experimental) on one day and saline (placebo) on another day (order randomised; double-blind cross-over design).
Drug: Ghrelin
Participants in this arm will receive a subcutaneous injection of acyl-ghrelin as the active condition.
Other Names:
  • Acyl-ghrelin
Drug: Saline
Participants in this arm will receive a subcutaneous injection of saline as placebo control condition.
Other Names:
  • Placebo

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Ghrelin-induced changes in motivation
Time Frame: 15-50 minutes after subcutaneous administration (ghrelin vs. saline)
Frequency of button presses on a XBox controller to obtain rewards after ghrelin administration vs. saline administration
15-50 minutes after subcutaneous administration (ghrelin vs. saline)
Ghrelin-induced changes in Resting Energy Expenditure
Time Frame: Pre injection versus 50-65 minutes after injection (compared to saline)
Changes in energy expenditure after a ghrelin administration (vs. saline) as measured with indirect Calorimetry.
Pre injection versus 50-65 minutes after injection (compared to saline)
Ghrelin-induced changes in mood
Time Frame: Pre injection timepoints (mean over 40 minutes and 5 minutes before) versus post injection timepoints (mean over 15, 50 and 65 minutes after injection) (compared to saline)
Changes operationalized via visual analogue ratings (0-100) of the sum score of positive and negative affect schedule mood items after ghrelin administration vs. saline administration. Measures are taken ~40 minutes and 5 minutes prior to injection, as well as 15, 50, and 65 minutes after injection.
Pre injection timepoints (mean over 40 minutes and 5 minutes before) versus post injection timepoints (mean over 15, 50 and 65 minutes after injection) (compared to saline)
Ghrelin-induced changes in hunger and satiety from baseline
Time Frame: Pre injection timepoints (mean over 40 minutes and 5 minutes before) versus post injection timepoints (mean over 15, 50 and 65 minutes after injection) (compared to saline)
Change in visual analogue scale (0-100) measures of subjective hunger and satiety after ghrelin administration vs. saline administration. Measures are taken ~40 minutes and 5 minutes prior to injection, as well as 15, 50, and 65 minutes after injection.
Pre injection timepoints (mean over 40 minutes and 5 minutes before) versus post injection timepoints (mean over 15, 50 and 65 minutes after injection) (compared to saline)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University Hospital Tuebingen

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Nils B Kroemer, PhD, University of Tübingen, Faculty of Medicine, Department of Psychiatry & Psychotherapy

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 2, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 20, 2024

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 20, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 21, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 26, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 28, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 22, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 15, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2024

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • TUE008_ADMIN

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

After the publication of the key results of the study, behavioral data will be shared after aggregation at the trial or participant level.

IPD Sharing Access Criteria

Until the data is publicly available, researchers may contact the lead PI to gain access

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF
  • ANALYTIC_CODE

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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