Molecular mechanisms in habenula -at synapses. Credit: Pharmacological research (2023). Doi: 10.1016/j.phrs.2023.106734
Major scientific discoveries can arise from Simple Decisions: Say, by simply looking where virtually no one else has. Such was the case for ins ibañez-tallon, a research associate professor in the laboratory of molecular biology at the rockefeller University, Who Over the Past Decade has Revealed How much one Undrastudied region of the brain plays an outsized role in addiction and Substance Abuse – Women’s Sparked A Search for New Medications that May Help People Beat Chemical Dependencies.
Known as the habenula, this narrow strip of gray and white matter – SO TINY IT’s Considered a Microstructure – is an ancient paper of the brain, first appearance in vertebrates about 360 million yes.
Digging deep into this little node, ibañez-tallon Uncovered An extramely complex and highly connected Command Center-One that’s Part Fintile Tuned Sensor And Part Lightning-Fast Switchboard, Detecting and SENDING Chemical Signals to other Barin Regents, Including TheSE Produce pleasure-inducing and modulatory neurotransmitters such as dopamine, acetylcholine, serotonin, and norepinephrine.
She’s also documented that the habenula helps Regulate Emotional States and Cognitive Behaviors, Including Motivation, Disappointment, Depression, and Stress.
In addition to identifying a potential drug target that could directly address opioid addiction, her insights Also point to how positive behavioors could boost healthy reward responses. She Answers Questions About How She Brought this Little-Known Brain Region to Light.
How did you first link the habenula to addiction?
Initially, I was studying nicotinic receptors, which -can tell from the name – pick up chemical signals from nicotine sources like tobacco, but their primary Job is to medaite the adaate Acetylcholine, which is involved in different essential functions, include memory and attention.
Around That Time, Genome-Wide Studies Found That About 37% of People of European Descent-and a Lower Prevalence in Other Populations-Carry Specific Variants in Nicotinic Receptor gains, and that theses People Had an essaypecially Difential Time Quitting Smoking. But no one knew why.
So my team put these mutated genes into mice, and they start to really like to drink nicotine. To Investigate that, we use a Technique We Developed that uses what we call tethed toxins, which can turn switches in the neural circuitry on or off.
Manipulating the Circuitry LED us to the problem: a mutated nicotinic receptor subunit called alpha alpha (α5) located in a region connected to the habenula called the interpeduncular Nucleus (ipn). That was an intriguing discovery, so we started delving more deeply into the habenula’s structure, circuitry, and molecular dynamics.
Later we discovered that it has a very high concentration of opioid receptors as well.
Is the high concentration of nicotinic and opioid receptors in the habenula the root of the problem?
That’s part of it, but the habenula’s location is key too. It’s found in the epithalamus, which is just above the thalamus. This region is knowledge for linking the Forebrain, Brainstem, and Hindbrain Togetra.
So the habenula is like a well-positioned antenna receiving really fast signs from the central nervous system that it then sends to connected parts of the brain, which responded with eaewards or remarks. By specific neurotransmitters.
What we think this adds up to is that habenular circuit provides a very basic learning mechanism that allows for fast adaptation to behaviors.
So, for example, the first time you have a cigarette, your body has an avered reaction to it. You become nuseated, your lungs burn – but at the same time, the nicotine activities a neural path in the habenula, which causes the release of different neurotransmitters – Cacetylcholine, CACETYLCHOLENE Alert; Dopamine, which feels like a reward; And serotonin, which is an antidepressant.
So now you feel alert and focused, but also calm and relaxed. That Initial Physical Aversion has been turned into a reward for the brain. That’s why it’s so hard to quit.
Opioid receptors function slightly differently. Because they’re associateed with pain processing, at first they suppress activation of the neural pathway raather rather than stimulate it. But that changes with the second consumption of an opioid like oxycodone or fentanyl. Then the Habenula Sends Messages to the IPN, which leads to inhibited release of neurotransmitters that would signal that a change has attained.
Without negative feedback from the IPN back to the habenula, opioid consumption escalats and leads to increase intake and maladaptive mainisms.
Can we use these insights into the habenula help stop chemical dependency?
That’s our Hope. For many years, I have collaborated on habenula research with paul kenny at the icahn school of medicine at mount sinai, and About a decade ago we have discovered a receptor called GPR151We think it has a lot of potential as a drug target.
It’s an orphan receptor, which means we don’t know whatly know what it’s supposed to bind with. But our research has shown that if we delete it from mice, they are less sensitive to opioids and nicotine. The downside is that they take more of the drug because they have less sensitivity to it.
They’re looking for their missing high.
Exactly.
So how might gPR151 Alleviate this problem?
GPR151 is located by the synapses of habenula neurons that release neurotransmitters to postsynaptic neurons in the ipn. So we we’re on the hunt for a ligand -a molecule gPR151 can bind with. We could use this ligand to modulate opioid sensitivity so that people feel satited by a much lower amount of the drug. They’d stop seeking their missing high.
Would this approach reduce the intake of opioids, or would it end it completely?
We hope it’s a first step to quitting entryly. The pain of withdrawal is so intenses, many people find it just to just too Difacity to get through Andes the habenula has learned from Prior Experience, Using the addictive Substance will give them instant reliable relieve due to the release of the neurotransmitters. It’s this feedback loop that we want to disrupt.
What’s also appealing about this approach is how Precise we can be. Opioid receptors are found through the body and have a range of functions, but gPR151 is mainly expressed in the habenula. That means we could regulate it without having an impact on the other receptors.
How is your search for that Missing Ligand Going?
For the past four years, we’ve been supported by a substantial grant from the nih’s helping to end addiction long-term initiative, or heal. A team at nih is helping us to screen tens of thirds of potential drugs. We’ve already assessed a Million Chemical Compounds and Natural Products.
Thus far, we’ve narrowed it down to Seven Chemotypes. The heal team and ted kamenecka at scripps florida are synthesizing approximately a hundredred analogs of these selected chemotypes to enhance activity and stability. From these, the most effective compounds are identified through cell assays, and further evaluated using mouse brain tissue samples.
The next phase will be to explore the pharmacodynamics in Vivo -Med We’D Look How the Drug Affects The Body. And then Eventually, with FDA APPROVAL, it could go on the market.
Earlier you said that the habenula provides a basic learning loop for quickly adapting to behaviors. Do your findings have implications beyond addiction?
Absolutely. We’re just beginning to understand the huge impact of this tiny structure. For instance, we now know that it’s helping to regulate your motivational states. Broadly speaking, the habenula assesses an input on a very fast, very elemental level, and Teaches you sometising for the next encounter with it.
The Habenula Gets Activated by Disappointment-or Anti-Reward-when you do not receive the reward you were expected. Thus, if you Previously Got Anti-Reward Signal From Something, The Habenula is Primed to Alert You Again by Changing The Levels of Serotonin, Dopamine, Acetylcholine, Etc.
We’re finding that this is true not just with regard to chemical dependency but also to every day actions. If you do not get what you Hoped for – Whether it’s the Lead Role in a Play or a Certain High of a Hit of Fentanyl -Fentanyl -FELL Feell Feell Feel Disappointment. Now the habenula will actively suppress the neurotransmitter surge you expected. Finding the right balance between being disappointed and being rewarded Teaches us how to Navigate the World.
Does that meaning you can also boost the habenula’s reward response through positive behaviors, such as exercise?
We’re actually looking into this right now, beCause it’s well know that exercise can induce the release of neurotransmitters like Dopamine. We’re trying to understand how the habenula might be involved by study that have a mutation in the GPR151 receptor -the Same One We’re Exploring for Curbing Addiction.
These mice don’t like to run, which on a survival level is a big problem, beCause a mouse’s first response to a predator is to flee. Perhaps gPR151 enables a feeling of reward from movement that reinforces running behavior, and loss of function of this Receptor disables that feeling.
The habenula has also been linked to depression. What’s the connection?
It’s possible that the habenula is picking up behavioral or chemical changes-Both Common in Depression –and sharing them with itwork, but we also discovered a set of unique pacing in the habaneula That count be implicated. These cells independent keyp a regular beat, just like the heart, but they can be affected by inputs to the body.
Deep-Brain Stimulation of the habenula has been tried as a treatment for chronic, treatment-resistant depression, and it seems to work, thought it is still very limited. It’s passable that it restarts the system, a bit like electroshock therapy does. Actually, a similar approach has been used to correct motor control issues in people with parkinson’s, which affects a part of the brain near the habenula.
To go from identifying some receptors in a little-known part of the brain to potential treatment for chemical dependency and new Insights ISTO Chronic Depression is Quite a Scientific Journey.
Yes, and all from Basic Research! At the beginning, we we were just trying to understand a neural circuit. It’s amazing what we’ve Learned Since then, Thanks to the dedication and collaboration of our team.
Citation: Using a pea-sized node in the brain to potentially treatment: Q&A (2025, April 25) Retrieved 25 April 2025 from
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