The use of mouse pituitary fragments to study LH secretion

This work evaluated a perifusion system for studying LH secretion from the anterior pituitary (AP) of female mice. Pituitary fragments were challenged with LHRH, and the effluents assayed for LH. In general, the tissue exhibited augmented release to repeated stimulation. In the dose-response study, the amount of LHRH required to produce maximum and half maximum responses dropped almost 10 fold by the 3rd stimulus. In response to various pulse frequencies LH release increased with the frequency of the 100 nM LHRH dose, but the tissue became refractive to constant nonpulsatile stimulation. Other preparations, subjected to high-frequency 10 nM LHRH pulses, released LH in two distinct episodes. All but the first hour of the response was blocked by cycloheximide, confirming the role of protein synthesis in the sustained release of LH. By varying both the pulse frequency and amplitude, a LHRH protocol was found that produced a proestrous-like surge. Lastly, rat and mouse tissues responded similarly to pulsatile LHRH, verifying their similar LH function during the preovulatory period. These studies demonstrate that the perifusion technique can be used for studying LH secretion in the mouse. Its application to other mouse-oriented studies is planned.