Activation of FOS in hypocretin neurons of the rat by insulin-induced hypoglycemia.
OBJECTIVE
The aim of the present study was to investigate the extent of activation of hypocretin (HCRT) synthesizing neurons after a single intraperitoneal administration of insulin using Fos-HCRT dual immunohistochemistry. In addition, there was also an attempt to depict the spatial organization of activated HCRT perikarya within the whole portion of the medial and lateral hypothalamic (LHA) areas.


METHODS
The animals (rats) were fixed 90 min after i.p. administration of insulin (2.5 IU/kg). The brains were removed, and sectioned through the hypothalamus into 40 microm thick alternate coronal sections. Fos-HCRT perikarya were double immunostained with avidin-biotin-peroxidase (ABC) technique using Nickel-DAB and single DAB as the two chromogens. For the mapping of Fos-HCRT double-labeled perikarya a light microscopy was employed. Counting of Fos-labeled HCRT perikarya was performed manually and blindly with no insight into the treatment of the animals.


RESULTS
The data demonstrate that in the early phase of the acute hypoglycemia, the number of the dually labeled Fos-HCRTir perikarya in the entire LHA was only moderately increased from 9.54 to 15.64% in spite of the fact that within the same period the plasma glucose levels were declined by more than 70%. Moreover, within the LHA, the distribution of activated double-labeled Fos-HCRTir perikarya did not show any special spatial organization.


CONCLUSIONS
The present data indicate that a large fall in plasma glucose in early phase of acute hypoglycemia does not represent an appropriate stimulus for massive activation of HCRT neurons in the LHA of rats.
Kiss
Alexander
A
Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, 833 06 Bratislava, Slovak Republic. ueenkiss@savba.sk
Jezova
Daniela
D
Mikkelsen
Jens D
JD
D000818:Animals; D007003:Hypoglycemia / Q000139:chemically induced / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism; D007150:Immunohistochemistry; D007328:Insulin / Q000008:administration & dosage; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos