Immunocytochemical localization of luteinizing hormone-releasing hormone (LHRH) and LHRH-like material in brain. Influence of fixation solution at various pH values.

The amount and distribution of luteinizing hormone-releasing hormone (LHRH) immunoreactive (ir) material in the hypothalamus, and of a LHRH-like immunostained substance in the rat pineal gland were examined employing Bouin's and Zamboni's fixation solutions at various pH values, and antisera generated against synthetic LHRH. The hypothalamic LHRH immunoreaction product is optimally visualized in this study when the pH value of the fixation solution is basic; conversely, the pineal LHRH-like ir material is seen only with an acidic pH value of the fixation solution. The present study demonstrates that the pH value of the fixation solution contributes substantially to the amount and distribution of some peptides visualized immunocytochemically in the brain.