Cannabinoids, MCH and Orexins in the Human Hypothalamus

[mofeta]

Here is a very interesting paper from a few years ago.

Cannabinoids Excite Hypothalamic Melanin-Concentrating Hormone But Inhibit Hypocretin/Orexin Neurons: Implications for Cannabinoid Actions on Food Intake and Cognitive Arousal



The upshot of this paper is this:

Cannabinoids do a lot more than we thought. This paper tells how cannabinoids can regulate levels of very important hormones in the brain (MCH and hypocretin/orexin). Also of note is the mechanism behind this regualtion. Previous studies show how cannabinoids exert their influence on neurons directly, by modulating potassium and calcium ion channels. This paper shows how cannabinoids can work pre-synaptically by controlling the amounts of GABA and glutamate (GABA is the primary inhibitory neurotransmitter, glutamte the primary exitatory neurotransmitter).

 

[ran outta love]

Can anyone who understands this please translate the functional relevance chapter into something understandable by a layman?

Are they saying cannabis "may" cause changes in activity levels and appetite? That's how I understand it. I would also have to agree that it may indeed do that.

 

[mofeta]

Can anyone who understands this please translate the functional relevance chapter into something understandable by a layman?

Are they saying cannabis "may" cause changes in activity levels and appetite? That's how I understand it. I would also have to agree that it may indeed do that.

No problem. Your take on it is basically correct, but I'll fill in some details for you. It takes some practice to learn how to translate science-talk into normal language, but if you do it a lot it becomes easier. Try it! At first it will take a long time, you will need to look up a lot of terms (make sure you look up the definitions in the proper context, scientists use a lot of common words that have a different meaning in the context of the science than the meaning in everyday speech).


First paragraph:

LH MCH neurons appear to play an important role in energy homeostasis (Williams et al., 2001; Berthoud, 2002). Previous studies have suggested a role for cannabinoids in enhancing food intake (Di Marzo and Matias, 2005; Sharkey and Pittman, 2005). Previous experiments showed that both electrical and chemical stimulation of this hypothalamic region increase food intake (Bernardis and Bellinger, 1996). MCH, which is selectively synthesized by LH area neurons, increases food intake and body weight. The results of the present study show that cannabinoids may depolarize and enhance the activity of MCH neurons, suggesting that some of the reported orexigenic actions of cannabinoids could be explained by their synaptic effects on MCH neuronal activity. This is consistent with the view that MCH cells may integrate signals from both leptins and endocannabinoids (Jo et al., 2005). Another possibility by which cannabinoids might modulate feeding is by inhibiting arcuate nucleus proopiomelanocortin (POMC) neurons that are involved in the repression of food intake; however, cannabinoids reduced GABA synaptic inhibition of POMC cells, potentially raising POMC neuron activity (Hentges et al., 2005). Because POMC neurons are thought to reduce food intake, a CB1R-mediated excitation of these cells is less likely to explain the enhancement of energy stores evoked by cannabinoids in the hypothalamus. Thus, the excitatory effect on MCH cells might be a possible hypothalamic site for the orexigenic action of cannabinoids.

Key definitions to understand above:

energy homeostasis: the process of balancing the intake of food with how much activity (calories burned) = eat too much and exercise too little: get fat-- eat too little, exercise too much: get skinny

orexigenic: makes you hungry (munchies)


Translation:
A certain part of the brain (lateral hypothalamus) controls feelings of hunger. Studies have shown that pot can give the munchies. Electical stimulation of this part of the brain can also give the munchies. A hormone in the hypothalamus called MCH can also give the munchies. This paper shows how pot might give you the munchies by affecting MCH. We have ruled out another way that pot might give you the munchies, so we are pretty sure it is affecting MCH.

Try translating the rest yourself. If you can't do it, I'll do the other two paragraphs later when I have time.

 

[ran outta love]

Hehe I'm quite proficient at reading scientific text. I just have no background whatsoever in neuroscience (or any related field) and need to consult an expert like yourself to really grasp what's going on with an advanced paper like this. Looking up the terms I don't understand won't do it. Thank you for the translation if you find time for the rest that would be great.