食物的香味为何让你食欲大增？3月《自然—神经科学》上的一项研究找到了原因——大脑嗅球中1型大麻素（CB1）受体的存在。这项研究还发现CB1受体的激活可以加强气味感知从而促进食物摄取，研究人员同时认为这些受体为改变导致肥胖的进食行为提供了一个潜在的药理学靶向。

短时间的节食行为被认为可以增加哺乳动物大脑中内源性大麻素的水平浓度。饥饿也被认为可以增强我们对气味的感知并促进食物消化。Giovanni Marsicano等人报告称，小鼠的嗅球中含有CB1受体，可通过内源性或外源性大麻素（比如大麻中的大麻素）将其激活，从而增强食物的快速摄取。而实际上，小鼠在获得外源性大麻素刺激（比如THC，大麻中的一种活跃成分）时，胃口大增的例子更常见。研究人员发现嗅球中的这类大麻素受体在进食行为的增加中也是必需的。

因为这种CB1受体似乎只在动物禁食或感到饥饿时才会产生增强食欲，所以嗅球中的CB1受体或可用作改变进食行为的一种潜在药理学靶向。

Nature Neuroscience              doi:10.1038/nn.3647

The endocannabinoid system controls food intake via olfactory processes

Edgar Soria-Gómez，  Luigi Bellocchio，  Leire Reguero，  Gabriel Lepousez，  Claire Martin， Mounir Bendahmane，  Sabine Ruehle，  Floor Remmers，  Tifany Desprez，  Isabelle Matias， Theresa Wiesner，  Astrid Cannich，  Antoine Nissant，  Aya Wadleigh，  Hans-Christian Pape， Anna Paola Chiarlone，  Carmelo Quarta，  Daniéle Verrier，  Peggy Vincent，  Federico Massa， Beat Lutz，  Manuel Guzmán，  Hirac Gurden，  Guillaume Ferreira，  Pierre-Marie Lledo

Hunger arouses sensory perception， eventually leading to an increase in food intake， but the underlying mechanisms remain poorly understood. We found that cannabinoid type-1 (CB1) receptors promote food intake in fasted mice by increasing odor detection. CB1 receptors were abundantly expressed on axon terminals of centrifugal cortical glutamatergic neurons that project to inhibitory granule cells of the main olfactory bulb (MOB). Local pharmacological and genetic manipulations revealed that endocannabinoids and exogenous cannabinoids increased odor detection and food intake in fasted mice by decreasing excitatory drive from olfactory cortex areas to the MOB. Consistently， cannabinoid agonists dampened in vivo optogenetically stimulated excitatory transmission in the same circuit. Our data indicate that cortical feedback projections to the MOB crucially regulate food intake via CB1 receptor signaling， linking the feeling of hunger to stronger odor processing. Thus， CB1 receptor–dependent control of cortical feedback projections in olfactory circuits couples internal states to perception and behavior.

转自生物谷