The effect of medial forebrain bundle lesion on thyrotropin secretion in the rat.
The medial forebrain bundle (MFB) was partially lesioned with 6-hydroxydopamine (6-OHDA) in order to investigate the effect of deficient central noradrenergic regulation on thyrotropin (TSH) secretion in the rat. 6-OHDA injection into the MFB significantly reduced the noradrenaline (NA), dopamine (DA) and serotonin (5-HT) content of the whole hypothalamus. NA and 5-HT concentrations were also significantly decreased in the paraventricular nucleus (PVN). The MFB lesion did not affect the clonidine (250 micrograms/kg, i.p.) induced stimulation of TSH release or the isoproterenol (1 mg/kg i.p.) induced decrease in TSH levels. Thyrotropin releasing hormone (TRH, 5 micrograms/kg i.v.) caused a similar significant stimulation of TSH secretion in lesioned and non-lesioned rats. The present results do not support the hypothesis that the blunted TSH response to TRH observed in depressed patients results from a deficiency in noradrenergic neurotransmission.
Jaffer
A
A
Department of Chemical Pathology, University of Stellenbosch, Tygerberg Hospital, R.S.A.
Daniels
W M
WM
Russell
V A
VA
Taljaard
J J
JJ
D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000502:physiology*; D016627:Oxidopamine / Q000494:pharmacology; D016548:Prosencephalon / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology
D012701:Serotonin; D013973:Thyrotropin-Releasing Hormone; D016627:Oxidopamine; D013972:Thyrotropin; D007545:Isoproterenol; D003000:Clonidine; D004298:Dopamine; D009638:Norepinephrine