title: Epitalon influences pineal secretion in stress-exposed rats in the daytime.
abstract: OBJECTIVE
  The content of C-Fos protein was tested in rat pinealocytes in the norm and stress and in case of intranasal administration of Epitalon (Ala-Glu-Asp-Gly), which regulated pineal secretion processes, presumably, via protooncogenes.
  
  
  METHODS
  Intact and osmotic-stress-exposed rats were used for the immunohistochemical detection of C-Fos protein. All animals were intranasally administered with Epitalon, the last infusion made in two hours before the biopsy. Simultaneously, light microscopy of the pineal parenchyma was performed in all groups of animals.
  
  
  RESULTS
  A slight but significant C-Fos increase was observed only in stress-exposed pinealocytes of rats after intranasal Epitalon infusions. C-Fos was irregularly distributed throughout pineal cells. In stress, the clusters of 5 10 cells containing C-Fos in their cytoplasm were detected. The dilation of capillaries and pericapillary space induced by an osmotic stress was partially reduced by the intranasal infusions of Epitalon.
  
  
  CONCLUSIONS
  Tetrapeptide Epitalon is synthesised on the basis of the amino acid composition of pineal peptide extract Epithalamin. Epitalon modulates pineal secretion only under a stress impact but never in the norm. It prevents osmotic-stress-induced pathologic changes in the pineal parenchyma structure. Besides, the physiological activity of Epitalon seems to be mediated by the activation of protooncogenes in pinealocytes.
authors.affiliation: Laboratory of Reception Physiology, Acad. I.P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Embankment, 199034 St. Petersburg, Russia. dima@das.stud.pu.ru
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Sibarov
authors.forename: Rimma I
authors.initials: RI
authors.lastname: Kovalenko
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Malinin
authors.forename: Vladimir Kh
authors.initials: VKh
authors.lastname: Khavinson
mesh_terms: D000281:Administration, Intranasal; D000818:Animals; D002196:Capillaries / Q000187:drug effects; D005508:Food Deprivation; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D017440:Photoperiod; D010870:Pineal Gland / Q000098:blood supply / Q000166:cytology / Q000187:drug effects* / Q000503:physiopathology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000503:physiopathology*; D014664:Vasodilation / Q000187:drug effects; D014868:Water Deprivation; D014882:Water-Electrolyte Balance
chemical_list: D009842:Oligopeptides; D016760:Proto-Oncogene Proteins c-fos; C421253:alanyl-glutamyl-aspartyl-glycine