title: Osmoregulation of the magnocellular neuroendocrine system during lactation.
abstract: Glucose utilization and Fos expression were used to compare responses of cerebral structures involved in osmoregulation in virgin and lactating rats given 0.15, 0.85, or 1.5 M NaCl subcutaneously. In virgin animals, glucose utilization increased (P < 0.05) in the supraoptic nuclei (SON), paraventricular nuclei (PVN), and neural lobe (NL) proportionally to the osmotic stimulus (0.15 M NaCl < 0.85 M NaCl < 1.5 M NaCl), whereas metabolism in the median preoptic nucleus (MPO) and median eminence (ME) increased only after 1.5 M NaCl. In lactating rats, enhanced utilization of glucose in response to osmotic stimulation was absent in the PVN (0.85 M NaCl), MPO, and ME or significantly (P < 0.01) reduced (SON, PVN, NL) compared with virgin animals. Glucose utilization in each structure correlated linearly with plasma osmolality but with a lower slope (P < 0.05) in lactating animals. Magnocellular neurons expressing Fos in the SON increased linearly with plasma osmolality and were more numerous (P < 0.05) in control lactating animals but increased less (P < 0.05) than in virgin rats after 0.85 M NaCl. The attenuated magnocellular response during lactation results from reduced afferent activation from osmosensitive forebrain sites.
authors.affiliation: Department of Pharmacology, M. S. Hershey Medical Center, Pennsylvania State University, Hershey 17033, USA. js12@email.psu.edu
authors.forename: J Y
authors.initials: JY
authors.lastname: Summy-Long
authors.forename: S
authors.initials: S
authors.lastname: Gestl
authors.forename: M L
authors.initials: ML
authors.lastname: Terrell
authors.forename: G
authors.initials: G
authors.lastname: Wolz
authors.forename: M
authors.initials: M
authors.lastname: Kadekaro
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism* / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D007774:Lactation / Q000502:physiology*; D009474:Neurons / Q000378:metabolism; D009490:Neurosecretory Systems / Q000502:physiology*; D011247:Pregnancy; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000378:metabolism; D014882:Water-Electrolyte Balance
chemical_list: D005227:Fatty Acids; D016760:Proto-Oncogene Proteins c-fos; D012462:Saline Solution, Hypertonic; D005947:Glucose