INVERSE RELATIONSHIP BETWEEN BETA-ENDORPHIN IMMUNOREACTIVITY IN CEREBROSPINAL-FLUID AND NUCLEUS-TRACTUS-SOLITARIUS IN SUDDEN INFANT DEATH

In nucleus tractus solitarius (NTS) beta-endorphin (BEND) induces brad ycardia and respiratory depression which have been reported to precede death in sudden infant death (SID). Of SID victims, 50% have elevated levels of beta-endorphin immunoreactivity (BENDI) in the cerebrospina l fluid (CSF), and 50% had undetectable levels. We therefore investiga ted the relationship of BENDI in the CSF to BENDI levels in the NTS ar ea. This study included SID victims (CSF from n = 47, brain stem from n = 16), borderline SID victims (CSF and brain stem from n = 2), sudde n death in childhood (CSF and brain stem from n = 1), and controls (CS F from n = 32, brain stem from n = 11). BEND in CSF and NTS area, afte r extraction, was measured by radioimmunoassay. High performance liqui d chromatography was used for closer identification of BENDI. We found that the SID victims divided into two subpopulations, one having a re latively high BENDI level in CSF and one having no detectable level (P < 0.01). Furthermore, an inverse relationship was found between BENDI level in CSF and BENDI level in NTS area in the SID victims (P < 0.05 ). We conclude that increased BENDI level in CSF is associated with lo w BENDI level in the NTS area in 50% of SID victims. The low BENDI lev el in the NTS area may be due to increased release of BEND.