[2 variants of the radioimmunochemical method of determination of LH-releasing factor (LH-RF). Distribution of LH-RF in various hypothalamic structures].

The authors elaborated two variants of the radioimmunochemical method of determination of the LH-releasing factor (LH-RF). Diluted antisera (AS) obtained by the immunization of rabbits with the LH-RF-ovalbumin were used in the first method; AS polymerized with isobutyl ester of chlorcarbonic acid were used in the second one. The minimal amount of the hormone determined in the I variant was 5 pg, and in the 11 one--20 to 30 pg. The method is highly specific, since the antisera gave no cross reaction with a wide set of protein-peptide hormones synthesized with the hypothalamus and the hypophysis. The presence in the samples of tissue components of the hypothalamus and of the cerebral cortex extractable with 2M CH3COOH failed to influence the precision of the test. In examining the LH-RF content in the brain structures there was revealed that in the sexually mature male rats the whole hypothalamus contained an average of 7.5 ng, the arcuate nuclei--1.5 ng and the medial eminence--2.5 ng of LH-RF; the supraoptic nuclei and the cerebral cortex contained no LH-RF determinable by the method described. Two weeks after the castration the mean content of the hormone in the whole hypothalamus decreased to 5.5 ng, in the medial eminence--to 0.6 ng, and showed no significant change in the arcuate nuclei.