A COMPARTMENTALIZED CHAMBER FOR STUDYING DOPAMINE NEURONS IN AN HYPOTHALAMOPITUITARY EXPLANT

An in vitro technique was developed which could be used to study whole neurons of the tuberohypophyseal dopaminergic (THDA) tract. Explants containing the medial basal hypothalamus (MBH; THDA cell bodies), pitu itary stalk (THDA axons) and posterior pituitary (PP; THDA nerve termi nals) were carefully dissected and placed in specially designed chambe rs. The chambers consist of separate compartments for the incubation o f the MBH and PP while maintaining an intact pituitary stalk which tra verses through a notched barrier. Dopamine (DA) synthesis in the expla nts was constant for 3 h and was significantly elevated by electrical stimulation. Electrical stimulation of both the PP and MBH increased e ndogenous DA release from the PP. DA release in response to potassium depolarization and dopaminergic drugs was significantly lower in expla nts than in the isolated PP even though spontaneous release was simila r. Conclusions: (1) this method is suitable for studying intact THDA n eurons in vitro, and (2) intact THDA neurons respond differently to va rious stimuli than their excised terminals.