Blockade of opioid receptors with naltrexone inhibits thyrotropin increase after noise stress but does not prevent the decrease caused by immobilization.
The influence of naltrexone-induced opioid receptor blockade on the response of thyrotropin to two different acute stressors was studied in adult male rats. Naltrexone slightly but significantly reduced basal thyrotropin levels and abolished the increase in serum thyrotropin caused by acute noise stress. In contrast, the opioid antagonist did not prevent the decrease in serum thyrotropin caused by another much more severe stressor such as immobilization. The present data offer the first evidence that endogenous opioids could play a stimulatory role in the control of thyrotropin secretion in a presumably physiological condition such as the response to a mild stressor. In addition, factors other than opioids could be involved in the inhibition of thyrotropin secretion under severe stress.
Armario
A
A
Departamento de Biología Celular y Fisiología, Facultad de Ciencias, Universidad Autónoma de Barcelona, Spain.
Marti
O
O
Gavalda
A
A
Jolin
T
T
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D009271:Naltrexone / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000503:physiopathology*; D013972:Thyrotropin / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism*
D011957:Receptors, Opioid; D009271:Naltrexone; D013972:Thyrotropin