title: Changes in diurnal fluctuations of plasma thyroid stimulating hormone and corticosterone following anterior hypothalamic deafferentation in the rat.
abstract: Systemic thyroid stimulating hormone (TSH) and corticosterone (B) levels were measured in serial plasma samples withdrawn from 8 adult female rats before and for several weeks after anterior hypothalamic cuts (FC), made with a modified Halász knife (1.5 mm radius). With lights on from 5:00 to 19:00 h the rats were bled by rapid venipuncture at 9:00 and 20:00 h 14 days before and 5 days after FC and by chronic intra-atrial cannulas at 9:00, 13:00, 17:00 and 20:00 h on days 25, 30 and 40 or 50 post-FC. The frontal cuts, localized later by histology to sites just rostral to the suprachiasmatic nucleus in 3 rats and just caudal to the nucleus in the other 5 brains, altered the charactersitic diurnal drop in plasma TSH and rise in B but did not eliminate marked fluctuations in hormone levels. The new hormonal platterns could not be related specifically to FC loci and appeared to be a dynamic process for each rat. At 5 days after FC the diurnal patterns were either obscured or shifted in phase. The most consistent finding at subsequent sampling intervals was that TSH and B plasma levels in each animal showed parallel fluctuations (during 9:00--20:00 h) as though synchronized in phase. The data suggest that interruption of anterior hypothalamic connections in the female rat is compatible with fluctuations in plasma TSH and B which are unique to a particular animal and may be obscured by group analysis.
mesh_terms: D000344:Afferent Pathways / Q000601:surgery; D000818:Animals; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood*; D005260:Female; D007031:Hypothalamus / Q000601:surgery*; D007032:Hypothalamus, Anterior / Q000601:surgery*; D051381:Rats; D013495:Supraoptic Nucleus / Q000601:surgery; D013972:Thyrotropin / Q000097:blood*; D013997:Time Factors
chemical_list: D013972:Thyrotropin; D003345:Corticosterone