Catecholaminergic innervation of oxytocin neurons in the paraventricular nucleus of the rat hypothalamus as revealed by double-labeling immunoelectron microscopy.
The catecholaminergic innervation of neurons that contain oxytocin in the paraventricular nucleus (PVN) of the rat hypothalamus was examined by a combination of methods in the same tissue sections at the electron-microscopic level as follows: (1) Rats were treated with 5-hydroxydopamine (5-OHDA) with peroxidase-antiperoxidase (PAP) staining of sections for oxytocin prior to embedding. (2) Preembedding immunoperoxidase staining with avidin-biotin complexes was used to demonstrate tyrosine hydroxylase (TH) activity, with postembedding staining with immunocolloidal gold for visualization of oxytocin. (3) Prior to embedding, a double-staining technique was used that was based on consecutive staining with silver-gold-intensified PAP complex and 3,3'-diaminobenzidine. We used an antiserum against oxytocin and an antiserum against dopamine-beta-hydroxylase (DBH) for localization of antigens. We found that TH- and DBH-like immunoreactive terminals were distributed throughout the rat hypothalamus and were abundant in all parts of the PVN. Ultrastructural observations revealed 5-OHDA-labeled, TH- or DBH-like immunoreactive axon terminals that contained granular vesicles (70-80 nm in diameter) and small clear synaptic vesicles (30-50 nm in diameter). The terminals appeared at times to be making synapses with cell bodies and with the processes of oxytocin-containing neurosecretory neurons in the PVN. These findings provide morphological evidence for a direct synaptic influence of catecholaminergic elements on the secretory activity of oxytocin-containing neurosecretory neurons in the rat hypothalamic PVN.
Horie
S
S
Department of Anatomy, Showa University School of Medicine, Tokyo, Japan.
Shioda
S
S
Nakai
Y
Y
D000320:Adrenergic Fibers / Q000648:ultrastructure*; D000818:Animals; D001369:Axons / Q000648:ultrastructure; D008297:Male; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000737:chemistry* / Q000648:ultrastructure; D010121:Oxytocin / Q000032:analysis*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar
D010121:Oxytocin