Studies On The Afferent Control Of The Hypothalamic Magnocellular Neurosecretory System In The Rat

The magnocellular neurosecretory system consists of oxytocin- and vasopressin- like immunoreactive (OT-LI and VP-LI) neurons distributed in the supraoptic nucleus (SON), paraventricular nucleus (PVN) and accessory cell groups in the hypothalamus. The efferent connections of these OT-LI and VP-LI neurons mainly contribute to the hypothalamo-neurohypophysial tract. It is indicated that the afferents of the magnocellular neurosecretory system have very complex chemical neuroanatomical and physiological features, and arise from various regions in the central nervous system. Most of the previous studies are involved in the afferent control of the OT- LT and VP-LI neurons in the SON and PVN. However, the accessory neurosecretory cell groups have been somewhat ignored.Much remains to be clarified for the magnocellular neurosecretory system and their functional significance. In the present study, we used immunocytochemical and double immunohistochemical staining (ABC procedure) , immunoelectron microscopy, double staining of anterograde PHA-L tract tracing and immunocytochemistry, and electrophysiological analysis to attempt a further understanding of the afferent control of the hypothalamic magnocellular neurosecretory system.Male Sprague Dawley rats were employed in our. investigations. The experiments consist of the following 6 parts:1. Relationship of monoamines and several kinds of peptide-containing processes with the magnocellular OT-LI and VP-LI cells of the hypothalamus.Sequential application of the avidin-biotin peroxidase complex (ABC) technique with the glucose oxidase-DAB-nickel method and DAB alone was...