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GnRH Secreting Neuron Dysfunction Identified in Down Syndrome

Published: 2022-09-02 - Updated: 2023-01-04
Author: INSERM (Institut national de la santé et de la recherche médicale) | Contact: inserm.fr/en/home/
Peer-Reviewed Publication: Yes | DOI: https://www.science.org/doi/10.1126/science.abq4515
Additional References: Therapy Publications

Synopsis: GnRH injection therapy was found to improve cognitive function in patients with Down syndrome. The laboratory demonstrated that five strands of microRNA regulating this hormone's production- found on chromosome 21 - are dysfunctional. Maintaining the GnRH system appears to play a key role in brain maturation and cognitive functions. In Down syndrome, pulsatile GnRH therapy is promising, especially as it is an existing treatment with no significant side effects. These promising findings now justify the launch of a more extensive study - with the inclusion of women - to confirm the efficacy of this treatment in people with Down syndrome, but also for other neurodegenerative conditions such as Alzheimer's disease.

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Definition

Down Syndrome

Down syndrome, Down's syndrome, or trisomy 21, is one of the most common chromosome abnormalities in humans. Down syndrome is a genetic disorder caused by the presence of all or part of the third copy of chromosome 21. There are three types of Down syndrome. People often can’t tell the difference between each type without looking at the chromosomes because the physical features and behaviors are similar. The average IQ of a young adult with Down syndrome is 50, equivalent to an eight- or nine-year-old's mental ability, but this can vary widely. People with Down syndrome have an increased risk of several other health problems, including a congenital heart defect, epilepsy, leukemia, thyroid diseases, and mental disorders. Down syndrome remains the most common chromosomal condition diagnosed in the United States. About 6,000 babies born in the United States each year have Down syndrome - about 1 in every 700 babies.

Main Digest

An Inserm team at the Lille Neuroscience & Cognition laboratory (Inserm/Université de Lille, Lille University Hospital) has joined forces with its counterparts at Lausanne University Hospital (CHUV) to test the efficacy of GnRH injection therapy to improve the cognitive functions of a small group of patients with Down syndrome. First, the scientists revealed dysfunction of the GnRH neurons in an animal model of Down syndrome and its impacts on the cognitive function impairment associated with the condition. Then, seven patients conducted a pilot study testing GnRH pulsatile injection therapy. The results were promising: the therapy improved cognitive function and brain connectivity. This study has been published in Science.

Related Publications:

Down syndrome, also known as trisomy 21, affects around one in 800 births and results in various clinical manifestations, including a decline in cognitive capacity. With age, 77% of people with the condition experience symptoms similar to those of Alzheimer's. Gradual loss of the ability to smell, typical of neurodegenerative diseases, is also commonly encountered from the prepubertal period, with potential sexual maturation deficits occurring in men.

GnRH Secreting Neuron Dysfunction Identified in Down Syndrome

Recent discoveries have suggested that the neurons expressing gonadotropin-releasing hormone (GnRH) - which is known for regulating reproduction via the hypothalamus - could also act on other brain regions with a potential role in other functions, such as cognition.

With this idea in mind, the Lille Neuroscience & Cognition laboratory team led by Inserm Research Director Vincent Prévot studied the mechanism which regulates GnRH in mouse models of Down syndrome.

The laboratory demonstrated that five strands of microRNA regulating this hormone's production- found on chromosome 21 - are dysfunctional. This supernumerary chromosome then leads to abnormalities in the neurons that secrete GnRH. These findings were confirmed at both genetic and cellular levels. The Inserm scientists were able to demonstrate that the progressive cognitive and olfactory deficiencies seen in the mice were closely linked to dysfunctional GnRH secretion.

Restoring GnRH Production to Restore Cognitive Function

The Inserm scientists then demonstrated that restoring physiological GnRH system function restores cognitive and olfactory functions in trisomic mice.

These findings in mice were discussed with Nelly Pitteloud, professor at the Faculty of Biology and Medicine of the University of Lausanne and head of the Endocrinology, Diabetology, and Metabolism Department at CHUV. Her research focuses on congenital GnRH deficiency, a rare disease that manifests by the absence of spontaneous puberty. These patients are given pulsatile GnRH therapy to reproduce the natural pulsatile rhythm of this hormone's secretion and induce puberty.

The researchers, therefore, decided to test the efficacy of pulsatile GnRH therapy on cognitive and olfactory deficits in trisomic mice, following a protocol identical to that used in humans. After 15 days, the team demonstrated the restoration of olfactory and cognitive functions in mice.

Pulsatile GnRH Therapy Improves Cognitive Function and Neural Connectivity in a Small Patient Group

The next stage for the scientists and doctors involved a pilot clinical trial in patients to evaluate the effects of this treatment. Seven men with Down syndrome, between 20 and 50 years of age, received one subcutaneous dose of GnRH every two hours for six months via a pump placed on the arm. Cognition and olfactory tests, as well as MRI exams, were performed before and after the treatment.

From the clinical viewpoint, cognitive performance increased in 6 of the seven patients with better three-dimensional representation, understanding of instructions, reasoning, attention, and episodic memory. However, the treatment had no impact on the ability to smell. These measures to improve cognitive functions were confirmed by brain imaging conducted by the CHUV Department of Clinical Neurosciences, which revealed a significant increase in functional connectivity.

These data suggest that the treatment acts on the brain by strengthening the communication between certain cortex regions.

"Maintaining the GnRH system appears to play a key role in brain maturation and cognitive functions," explains Prévot. "In Down syndrome, pulsatile GnRH therapy is looking promising, especially as it is an existing treatment with no significant side effects," adds Pitteloud.

These promising findings now justify the launch of a larger study - with the inclusion of women - to confirm the efficacy of this treatment in people with Down syndrome, but also for other neurodegenerative conditions such as Alzheimer's disease.

References:

GnRH Replacement Rescues Cognition in Down Syndrome

Maria Manfredi-Lozano1,2#, Valerie Leysen1,2#, Michela Adamo3,4#, Isabel Paiva5, Renaud Rovera6, Jean-Michel Pignat7, Fatima Ezzahra Timzoura1,2, Michael Candlish8,†, Sabiha Eddarkaoui1, Samuel A. Malone1,2, Mauro S. B. Silva1,2, Sara Trova1,2, Monica Imbernon1,2, Laurine Decoster1,2, Ludovica Cotellessa1,2,Manuel Tena-Sempere9, Marc Claret10, Ariane Paoloni-Giacobino11, Damien Plassard12, Emmanuelle Paccou3, Nathalie Vionnet3, James Acierno3, Aleksandra Maleska Maceski13, Antoine Lutti14, Frank Pfrieger15, S. Rasika1,2, Federico Santoni4, Ulrich Boehm8, Philippe Ciofi16, Luc Buée1, Nasser Haddjeri6, Anne-Laurence Boutillier5, Jens Kuhle13, Andrea Messina3,4, Bogdan Draganski14,17, Paolo Giacobini1,2, Nelly Pitteloud3,4*, Vincent Prevot1,2 *

† New address, Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.

# These authors contributed equally.

* These authors contributed equally.

Reference Source(s):

GnRH Secreting Neuron Dysfunction Identified in Down Syndrome | INSERM (Institut national de la santé et de la recherche médicale) (inserm.fr/en/home/). Disabled World makes no warranties or representations in connection therewith. Content may have been edited for style, clarity or length.

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Cite This Page (APA): INSERM (Institut national de la santé et de la recherche médicale). (2022, September 2). GnRH Secreting Neuron Dysfunction Identified in Down Syndrome. Disabled World. Retrieved January 27, 2023 from www.disabled-world.com/medical/rehabilitation/therapy/gnrh.php

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