[Different immunoreactive forms of hypothalamic LHRH].

The radioimmunological detection of higher molecular weight (HMW) forms of LHRH is attempted in acidic extracts of the rat hypothalamus. Three antibodies are used: antibodies directed against the N or the C terminal part of LHRH (N-or C-antibodies) and recognizing synthetic LHRH molecules with N or C peptidic extensions; one conformational antibody accepting none modification of LHRH extremities. Hypothalamic LHRH immunoreactivity is distributed between three peaks after molecular sieve filtration. The first one (peak I) is eluted in the void volume of the column. Its apparent molecular weight is estimated to 26,000 daltons. Its detection is possible with the N-antibody only. The second one (peak II) is eluted before the total volume of the column. The third one (peak III) is eluted like synthetic LHRH. Its detection is easy with all antibodies. Nevertheless, it is more important with the N-antibody. This peak corresponds to the native LHRH. The excess of the N-immunoreactivity has not been yet elucidated. Several immunological detections for the peak II also: easily detected by the N-antibody, it is partially recognized by the C-antibody. By using different molecular sieve filtrations, ion exchange or affinity chromatographies, it is suggested that molecules detected with the C-antibody could correspond to C-terminal catabolites of LHRH. Molecules recognized with the N-antibody would be a LHRH sequence extended on the C-part with 1,800 daltons for the apparent molecular weight.(ABSTRACT TRUNCATED AT 250 WORDS)