PMID- 3141000
OWN - NLM
STAT- MEDLINE
DCOM- 19881221
LR  - 20190614
IS  - 0006-8993 (Print)
IS  - 0006-8993 (Linking)
VI  - 461
IP  - 2
DP  - 1988 Oct 4
TI  - Responses from osmosensitive neurons of the rat subfornical organ in vitro.
PG  - 205-14
AB  - Extracellular recordings were made in vitro from 212 single units in the rat 
      subfornical organ (SFO) and 54 single units in the rat medial preoptic area 
      (MPO). Units were exposed to solutions made hyper-osmotic or hypo-osmotic by 
      1.4-11%. A reversible 30% or greater change in frequency followed the osmotic 
      challenge in tests of 66% of units in the SFO and 46% of units in the MPO. 
      Responses consisted of increases in frequency (excitations) or decreases in 
      frequency (inhibitions) and were either sustained for the whole test period or of 
      a transitory nature. Units responded to either hyperosmotic (SFO, 19%; MPO, 43%) 
      or to hypo-osmotic changes (SFO, 30%; MPO, 28.5%) or to both (SFO, 51%; MPO, 
      28.5%). The response pattern of the SFO and MPO was significantly different (chi 
      2 54.0, 3df, P = 0.0001). In both the SFO and MPO the stimulus to which the units 
      responded was a change in tonicity. This was indicated by the findings that 
      similar responses were evoked by hyperosmotic changes made with either mannitol 
      or NaCl and there was no response to solutions containing urea, either as an 
      additive, or as a substitute for NaCl. In the SFO, in the presence of synaptic 
      blockade produced by raising the Mg concentration in the bathing solution to 15 
      mM, the frequency of 19/27 units fell significantly. Responses of 40% of units to 
      osmotic pressure changes were blocked indicating these responses were 
      synaptically evoked. The responses which survived synaptic blockade when compared 
      with pre-blockade responses were more often transient (P less than 0.02) and more 
      often inhibitions. Post blockade there were also significantly more responses in 
      the SFO to hypo-osmotic than to hyper-osmotic changes (P = 0.01). Our results 
      suggest that while an ability to change their firing rate in response to small 
      changes of osmotic pressure may be a general property of neurons, the neurons of 
      the SFO are specialised for the detection of changes in the extracellular osmotic 
      pressure.
FAU - Sibbald, J R
AU  - Sibbald JR
AD  - Department of Physiology, University of Otago Medical School, Dunedin, New 
      Zealand.
FAU - Hubbard, J I
AU  - Hubbard JI
FAU - Sirett, N E
AU  - Sirett NE
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Brain Res
JT  - Brain research
JID - 0045503
RN  - 02F3473H9O (Magnesium Chloride)
RN  - 3OWL53L36A (Mannitol)
RN  - 8W8T17847W (Urea)
RN  - I38ZP9992A (Magnesium)
SB  - IM
MH  - Action Potentials/drug effects
MH  - Animals
MH  - In Vitro Techniques
MH  - Magnesium/pharmacology
MH  - Magnesium Chloride
MH  - Male
MH  - Mannitol/pharmacology
MH  - Neurosecretory Systems/*physiology
MH  - *Osmolar Concentration
MH  - Preoptic Area/drug effects/physiology
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Subfornical Organ/drug effects/*physiology
MH  - Urea/pharmacology
EDAT- 1988/10/04 00:00
MHDA- 1988/10/04 00:01
CRDT- 1988/10/04 00:00
PHST- 1988/10/04 00:00 [pubmed]
PHST- 1988/10/04 00:01 [medline]
PHST- 1988/10/04 00:00 [entrez]
AID - 0006-8993(88)90251-X [pii]
AID - 10.1016/0006-8993(88)90251-x [doi]
PST - ppublish
SO  - Brain Res. 1988 Oct 4;461(2):205-14. doi: 10.1016/0006-8993(88)90251-x.