Identification of some substances secreted by the bovine pineal body and their antigonadotrophic activity in an in vitro system.

To aid elucidation of the chemical composition of the antigonadotrophic substances produced by the epiphysis cerebri, 100 bovine pineal bodies were incubated in Krebs-Ringer buffer and the incubate treated to give an ethyl acetate and an aqueous extract. Using thin layer chromatography on fluorescent silica gel plates, 5 indoles were identified and 6 unknown substances isolated from the pineal incubate and from both extracts. The presence of peptides was detected in the incubate and in the aqueous extract. The antigonadotrophic activity of the incubate and of the two extracts was examined using a continuous flow in vitro system with the production of luteinizing hormone (LH) from bovine adenohypophysial tissue as the final parameter. All three fractions were found to result in a somewhat similar production of LH. To distinguish between the antigonadotrophic activity attributable to the indole and the indole/protein components of the pineal secretion, 90 bovine pineal bodies were homogenized and the homogenate incubated in the continuous flow in vitro system in the presence or absence of trypsin and trypsin-inhibitor. Results were inconclusive regarding the role played by the indole and indole/protein fractions in the antigonadotrophic activity of the pineal body.