Simulatory hypothyroidism pituitary function in vitro: dynamics of TSH release after TRH stimulation in perifused rat hemipituitaries.

The production of immunoreactive TSH by hemipituitaries (Hps) to the stimulation of TRH in perifusion with negligible influence of the feedback of secretogogues and hormones was analysed. The stimulations were of long term continuous (3 hrs) and short term (15 min), with the dose levels of 1, 10 and 100 ng per ml of medium (for 3 hrs) or in 2 ml (for 15 min). The largest amount in production and the fastest rate in release of TSH found in present report is at 10 ng level. Only total TSH, in tissue plus in medium, after continuous TRH stimulation were dose-related, but not in release alone. We present herein an analysis of pituitary TSH production, in a perifusion system under steady TRH stimulation. This arrangement is believed to be a condition simulating hypothyroidism in pituitary level and suitable for study of the functions of the pituitary with hyperactivated thyrotrophs.