Role of the central endogenous opiate system in patients with syndrome X.
BACKGROUND
To evaluate the role of the endogenous opioid system (EOS) in abnormal pain perception in patients with syndrome X, we used a neuroendocrine approach, evaluating plasmatic luteinizing hormone (LH) changes after naloxone, a competitive antagonist of opioid receptors able to unblock tonic EOS inhibition on gonadotropin release. Thus LH response to naloxone test indicates the central EOS activity on hypothalamic luteinizing hormone-releasing hormone (LH-RH) inhibitory opioid receptors.


METHODS
Ten patients with syndrome X, 10 age-matched male patients with coronary artery disease (CAD), and 10 normal subjects were analyzed. Naloxone tests were performed between 8 and 9 am. Basal beta-endorphin and LH levels were determined on 4 blood samples at 20-minute intervals; after naloxone (0.1 mg/kg intravenously in 4 minutes), LH was measured on 8 samples at 15-minute intervals. In all patients the test was also performed after LH-RH administration. Anginal pain on exercise testing was subjectively scored on a 1 to 10 analogic scale and wall motion abnormalities were quantified by a wall motion score index.


RESULTS
Significant differences were found in LH release after naloxone (CAD 260.3 +/- 42.6 vs syndrome X 151.6 +/- 48.5 mIU/mL, P <.05), angina score (CAD 5.5 +/- 1.3 vs syndrome X 7.2 +/- 1.7, P <.05), and wall motion abnormalities (CAD 3.6 +/- 1. 2 vs syndrome X 2.8 +/- 1.9, P <.05).


CONCLUSIONS
The reduced LH release after naloxone in syndrome X, with a normal LH-RH response, suggests a lower central EOS activity, which may be related to the higher anginal pain perception.
Fedele
F
F
I Cattedra di Cardiologia, Dipartimento di Scienze Cardiovascolari e Respiratorie, Università "La Sapienza di Roma" Rome, Italy.
Agati
L
L
Pugliese
M
M
Cervellini
P
P
Benedetti
G
G
Magni
G
G
Vitarelli
A
A
D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D017566:Microvascular Angina / Q000097:blood / Q000503:physiopathology*; D008875:Middle Aged; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D001615:beta-Endorphin / Q000097:blood*
D009292:Narcotic Antagonists; D009270:Naloxone; D001615:beta-Endorphin; D007986:Luteinizing Hormone