The effect of inclusion of cerebrospinal fluid in the incubation medium on the in vitro secretion of luteinizing hormone from the bovine adenohypophysis.

Six in vitro trials were conducted using bovine tissues to study the effects of addition of cerebrospinal fluid (C.S.F.) to the incubation medium on the secretion of luteinizing hormone (LH) from adenohypophysial tissue, both in the presence and absence of hypothalami. Additionally, a study was made of the effect of including pineal bodies on the secretion of LH in both medium alone and in medium + C.S.F. No marked or consistent effect on LH secretion was observed when the C.S.F. concentration ranged between 5 per cent and 40 per cent, when the tissues were incubated in C.S.F. alone, nor when pineal bodies were added to the culture system. These results do not support the concept that the C.S.F. contains substantial amounts of substances which enhance secretion of LH from the anterior pituitary.

Failure to demonstrate high concentrations of luteinising hormone-releasing hormone in the bovine pineal body.

Six in vitro experiments were conducted to study the effects of the incorporation into the culture system of 10 bovine pineal bodies (or a similar mass of bovine hypothalamic tissue) on the secretion of luteinising hormone (LH) from bovine adenohypophyseal tissue (anterior pituitary - AP). When hypothalamic tissue was incubated with AP tissue, an increased amount of LH was released into the medium but no marked increase in LH secretion was observed when pineal bodies were included in the AP culture system. Additionally, the amount of radio-immunologically active luteinising hormone-releasing hormone (LHRH) contained in bovine pineal bodies was much less than that contained in an equivalent mass of hypothalamic tissue. Thus, present results do not support the concept that the pineal body contains comparatively large amounts of lhrh.

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.