Effects on Plasma Luteinizing Hormone Levels of Microinjection of Noradrenaline and Adrenaline into the Septo‐Preoptic Area of the Brain of the Ovariectomized Ewe: Changes with Season and Chronic Oestrogen Treatment

Abstract

We have investigated the effects on luteinizing hormone (LH) secretion of noradrenaline (NA) and adrenaline (A) microinjected (1 μl) into the septo‐preoptic area of ovariectomized (OVX) ewes with or without oestrogen (E) treatment and across the breeding and non‐breeding seasons. Guide tubes (19 gauge) were placed into the septo‐preoptic area of OVX ewes using lateral ventriculograms for localization of the target area. The sheep were tamed so that injections could be made into conscious animals during blood sampling procedures. Jugular venous blood was collected at 10‐min intervals for 3 h, an injection of NA or A (10 μg) or saline was given and samples collected for a further 3 h. The plas..