Pulsatile luteinizing hormone secretion in the neonatal male rhesus monkey (Macaca mulatta)

In an attempt to establish whether the gonadotrophic hormones are secreted in a pulsatile mode during neonatal development in the rhesus monkey, four infantile males were bilaterally gonadectomized at 1-2 weeks of age. Sequential blood samples were taken 22-36 days later from each animal every 10 min for 3-4 h during the light phase of the 24-h light : darkness cycle and circulating LH concentrations were determined by radioimmunoassay. Plasma concentrations of this gonadotrophin fluctuated dramatically and in an apparently rhythmic fashion with peaks recurring at approximately hourly intervals. These findings indicate that the neonatal stage of ontogeny the hypothalamic-hypophysial apparatus which governs gonadotrophin secretion in this species is capable of generating a pulsatile or episodic pattern of LH release.