Reciprocal synaptic relationships between orexin- and melanin-concentrating hormone-containing neurons in the rat lateral hypothalamus: a novel circuit implicated in feeding regulation.
OBJECTIVE
Both orexin (ORX)- and melanin-concentrating hormone (MCH) are expressed in different neurons in the lateral hypothalamic area (LH), and are considered to have common effects on stimulating food intake. There are no reports to demonstrate neural interactions between them at the ultrastructural level. We observed these neurons in the LH to evaluate the relationships between them.


METHODS
We used two different types of double immunostaining to reveal the ultrastructure of both the ORX- and MCH-containing neurons. A preembedding double immunostaining technique was used to study the synaptic relationships between the two kinds of neuron.


RESULTS
The main new findings are as follows: 1) Both ORX- and MCH-containing neurons received other synaptic input and made synaptic input to other neurons; 2) Reciprocal synaptic relationships were observed between the ORX- and MCH-containing neurons.


CONCLUSIONS
The ORX- and MCH-containing neurons in the lateral hypothalamic area may influence food intake through synapse with each other.
Guan
J-L
JL
Department of Anatomy, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan.
Uehara
K
K
Lu
S
S
Wang
Q-P
QP
Funahashi
H
H
Sakurai
T
T
Yanagizawa
M
M
Shioda
S
S
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004435:Eating / Q000502:physiology*; D007026:Hypothalamic Area, Lateral / Q000378:metabolism*; D007028:Hypothalamic Hormones / Q000378:metabolism*; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008543:Melanins / Q000378:metabolism*; D008854:Microscopy, Electron; D009474:Neurons / Q000502:physiology / Q000648:ultrastructure*; D009479:Neuropeptides / Q000378:metabolism*; D000068797:Orexins; D010907:Pituitary Hormones / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000502:physiology*
D002352:Carrier Proteins; D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone