Scientists find sexual dimorphism in cannabinoid 1 receptor expression in mice

March 17, 2020

A major challenge in neuroscience lies in understanding how molecular and circuit differences in the brain synergistically contribute to sex differences in behavioral phenotypes. Sex differences in the brain may arise from the identity, distribution and relative abundance of cell types.

The cannabinoid 1 receptor (CB1R), the main receptor for cannabinoids and endocannabinoids (eCB), is the most abundantly expressed G protein-coupled receptor in the brain and is highly conserved in animal evolution. However, whole-brain mapping of CB1R expression in adult male and female mice had not previously been described in detail.

Recently, a research team led by Dr. WANG Feng from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences demonstrated that CB1R mRNA expression displays a sexually dimorphic pattern in several regions in the adult mouse brain.

According to their current study published in Journal of Comparative Neurology on January 29, a systemic mapping of CB1R mRNA expression was conducted and compared for the first time in male and female adult C57BL/6J mouse (a common inbred strain of laboratory mouse) brains.

The researchers found that the neocortex, medial habenula, striatum, hippocampus and cerebellum were enriched with CB1R mRNA signals.

In the orbital cortex, insular cortex, cingulate cortex, piriform cortex, secondary visual cortex, caudate putamen and ventral hippocampus CA1, there were significantly more CB1R positive cells in males than in females. On the contrary, in the fornix and dorsal hypothalamus, CB1R positive cells were displayed more in females.

It is plausible that the difference in CB1R expression in the brain contributes to sex differences in various phenotypes. For example, the striatum, which harbors a greater amount of CB1R positive cells in males, has been widely recognized as the main affected region in Parkinson's disease, which has a higher incidence in males. The dorsal hypothalamus, with a female-biased number of CB1R positive cells, is associated with maternal behaviors.

More interestingly, CB1R mRNA seems to fluctuate with the estrus cycle in female brain regions, including the medial amygdala, basolateral amygdala and parabrachial nucleus, which has not been reported before.

This study maps the localization of CB1R positive cells on a whole-brain scale in both genders for the first time. The findings provide a basis for understanding sexual dimorphism in physiological and pathological brain functions related to cannabinoids and endocannabinoids.

Chinese Academy of Sciences Headquarters

Related Hippocampus Articles from Brightsurf:

Brain remapping dysfunction causes spatial memory impairment in Alzheimer's disease
A research group elucidated the brain circuit mechanism that cause of spatial memory impairment in Alzheimer's disease.In the future, improving brain remapping function may reverse spatial memory impairment in patients with Alzheimer's disease.

Impact of family income on learning in children shaped by hippocampus in brain
A new study by a team of researchers at the University of Toronto identifies the region of the brain's hippocampus that links low income with decreased memory and language ability in children.

Inhibitory interneurons in hippocampus excite the developing brain
A new study from the George Washington University, however, reports that in some critical structures of the developing brain, the inhibitory neurons cause excitation rather than suppression of brain activity.

A good blood supply is good for memory
Memory performance and other cognitive abilities benefit from a good blood supply to the brain.

Scientists identify circuit responsible for building memories during sleep
Neuroscientists at the University of Alberta have identified a mechanism that may help build memories during deep sleep, according to a new study.

Lack of oxygen doesn't kill infant brain cells, as previously thought
Research, conducted at OHSU and published in the Journal of Neuroscience, raises new concerns about the vulnerability of the preterm brain to hypoxia.

Schizophrenia: Adolescence is the game-changer
Schizophrenia may be related to the deletion syndrome. However, not everyone who has the syndrome necessarily develops psychotic symptoms.

How the olfactory brain affects memory
How sensory perception in the brain affects learning and memory processes is far from fully understood.

Penn researchers discover the source of new neurons in brain hippocampus
Researchers have shown, in mice, that one type of stem cell that makes adult neurons is the source of this lifetime stock of new cells in the hippocampus.

Scientists find first evidence for necessary role of the human hippocampus in planning
A team of scientists reports finding the first evidence that the human hippocampus is necessary for future planning.

Read More: Hippocampus News and Hippocampus Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to