Biological assay of luteinizing hormone-releasing hormone (gonadorelin)

The abilities of luteinizing hormone releasing hormone (LHRH) to stimulate the release of luteinizing hormone (LH) in vitro from dispersed pituitary cells or from segments of adenohypophysial tissue have both been exploited in an attempt to develop biological assays for its determination. Columns of dispersed adenohypophysial cells were highly sensitive to LHRH. The responses appeared to be specific, but the marked continual variation in their magnitude rendered the system nonprecise. Pituitary segments were less sensitive to LHRH than the dispersed cells. However, their responsiveness was increased by pretreatment ('priming') with the releasing hormone. Over a wide range of doses, there was a linear relationship between the LH released by 'primed' segments and the logarithm of the concentration of LHRH. The dose-response lines of hypothalamic extracts were parallel with those of the synthetic peptide. The method using segments is accurate, specific, and precise and fulfils the essential requirements of a biological assay.