title: Regional-dependent increase of sympathetic innervation in rat white adipose tissue during prolonged fasting.
abstract: White adipose tissue (WAT) is innervated by the sympathetic nervous system. A role for WAT sympathetic noradrenergic nerves in lipid mobilization has been suggested. To gain insight into the involvement of nerve activity in the delipidation process, WAT nerves were investigated in rat retroperitoneal and epididymal depots after prolonged fasting. A significant increase in tyrosine hydroxylase (TH) content was found in epididymal and, especially, retroperitoneal WAT by Western blotting. Accordingly, an increased immunoreactivity for TH was detected by immunohistochemistry in epididymal and, especially, retroperitoneal vascular and parenchymal noradrenergic nerves. Neuropeptide Y (NPY)-containing nerves were found around arteries and in the parenchyma. Double-staining experiments and confocal microscopy showed that most perivascular and some parenchymal noradrenergic nerves also contained NPY. Detection of protein gene product (PGP) 9.5, a general marker of peripheral nerves, by Western blotting and PGP 9.5-TH by double-staining experiments showed significantly increased noradrenergic nerve density in fasted retroperitoneal, but not epididymal depots, suggesting that formation of new nerves takes place in retroperitoneal WAT in fasting conditions. On the whole, these data confirm the important role of sympathetic noradrenergic nerves in WAT lipid mobilization during fasting but also raise questions about the physiological role of regional-dependent nerve adjustments and their functional significance in relation to white adipocyte secretory products.
authors.affiliation: Institute of Normal Human Morphology, Marche Polytechnic University, Via Tronto, 10/A, 60020 Ancona, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Giordano
authors.forename: Andrea
authors.initials: A
authors.lastname: Frontini
authors.forename: Incoronata
authors.initials: I
authors.lastname: Murano
authors.forename: Cristina
authors.initials: C
authors.lastname: Tonello
authors.forename: M Antonella
authors.initials: MA
authors.lastname: Marino
authors.forename: Michele O
authors.initials: MO
authors.lastname: Carruba
authors.forename: Enzo
authors.initials: E
authors.lastname: Nisoli
authors.forename: Saverio
authors.initials: S
authors.lastname: Cinti
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology / Q000294:innervation* / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004822:Epididymis; D005215:Fasting; D005629:Frozen Sections; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal; D009478:Neuropeptide Y / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D009928:Organ Specificity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012187:Retroperitoneal Space; D013564:Sympathetic Nervous System / Q000378:metabolism; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000378:metabolism; D015431:Weight Loss
chemical_list: D015415:Biomarkers; D009478:Neuropeptide Y; D014446:Tyrosine 3-Monooxygenase; C489034:UCHL1 protein, rat; D043222:Ubiquitin Thiolesterase; D009638:Norepinephrine