Plasma testosterone and LH levels in male quail bearing hypothalamic lesions or radioluminous implants

Radioluminous material (RLM) was implanted in either the infundibular complex or the preoptic area of sexually immature quail exposed to short days. Direct selective photic stimulation of the infundibular complex resulted in testicular growth (3,300 mg) and increase in levels of plasma testosterone (T, 23 ng/10 ml) and luteinizing hormone (LH, 4 ng/ml). Direct selective photic stimulation of the preoptic area did not induce any testis enlargement (84 mg) and plasma T and LH levels remained low (1.4 ng/10 ml and 0.9 ng/ml). However, preoptic as well as infundibular lesioning completely suppressed any gonadotropic and testicular responses to environmental photic stimulation. The respective and possibly differential roles played by these 2 structures in the photosexual reflex are discussed.