chinese scientists in a laboratory environment

Source: Zhejiang University

Morphine addiction

New pathway target for addiction therapy found

Activating a neural pathway from the Ventral Tegmental Area (VTA) to the Dorsal Raphe Nucleus (DRN) could significantly reduce morphine addiction while not affecting its analgesic effect, suggests new research led by Prof. Li Xiaoming from Zhejiang University's School of Medicine.

The study, published in the January issue of Neuron, found two parallel inhibitory neural pathways from VTA to DRN: The rostral VTA (rVTA) sends more projections to the DRN GABAergic neurons, whereas the caudal VTA (cVTA) innervate more serotonergic neurons in the DRN. The former pathway was discovered to be specifically involved in morphine addiction.

VTA→DRN circuits
Source: ZJU

VTA and DRN are two important nuclei in the brain that participate in the regulation of emotion, cognition, memory and motor functions, especially in the reward and addiction pathway. The interaction between VTA and DRN has been an area of much scientific interest. As such, the team adopted retrograde tracing on the brain. “We first used the retrograde tracing to track the whole brain projections of DRN, and found there were two populations of GABAergic neurons in VTA projection to DRN. RVTA and cVTA GABAergic projections in the DRN exhibited opposite functions in reward-related behaviors, probably by contrasting regulation of DRN serotonergic neuronal activity,” said Dr. Li Yue, one of the first authors of the article.

Activating this pathway during opioid administration may be a new strategy to reduce the addiction properties without affecting the analgesic effects of morphine

Li Chunyue

Additionally, the team found that morphine receptors (MOPs) were differentially distributed in the rostral and caudal VTA GABAergic neuronal terminals within DRN, resulting in different modulation of these two circuits by chronic morphine exposure. Chemo-genetic activation of the rVTA→DRN inhibitory circuit blocked morphine-induced CPP (Condition Place Preferance) without affecting other behaviors. “Our results identified the rVTA→DRN inhibitory circuit as another key system mediating morphine reward. Activating this pathway during opioid administration may be a new strategy to reduce the addiction properties without affecting the analgesic effects of morphine,” explained Li Chunyue, another team member. Reviewers of Neuron magazine commented on the research as being “technically sophisticated” and a “timely study of the anatomy physiology of this system”. 

Source: Zhejiang University School of Medicine


Read all latest stories

Related articles

The science of sleep

How our brain works against night owls

‘Night owls’ – those who go to bed and get up later – have fundamental differences in their brain function compared to ‘morning larks’ , which mean they could be disadvantaged by the…

Oral contraceptives

Can birth control pills keep you from recognising emotions?

The pill could be blurring your social judgement ‒ but perhaps not enough so you'd notice. By challenging women to identify complex emotional expressions like pride or contempt, rather than basic…


Will education save you from dementia? Don't count on it

Until now, neurologists were largely convinced that having a higher level of education would build some kind of protective barrier against neurodegenerative diseases like Alzheimer's. But a new study…

Related products

Research use only (RUO)

Eppendorf - Mastercycler nexus X2

Eppendorf AG

Research use only (RUO)

SARSTEDT - Low DNA Binding Micro Tubes


Research use only (RUO)

Shimadzu - CLAM-2000

Shimadzu Europa GmbH