TY - JOUR
T1 - Electrophysiological identification of a pathway from the septal area to the medial amygdala
T2 - Sensitivity to estrogen and luteinzing hormone‐releasing hormone
AU - Dudley, C. A.
AU - Lee, Y.
AU - Moss, R. L.
PY - 1990
Y1 - 1990
N2 - Medial amygdala neurons responsive to electrical stimulationof the medial septal area were electrophysiologically identified in ovariectomized, urethane‐anesthetized female rats. Peristimulus time histograms were collected and used to define the orthodromic response. The action of iontophoretically applied luteinzing hormone‐releasing hormone (LHRH) and an LHRH fragment, Ac‐LHRH5–10, on the activity of were identified as orthodromically responsive. Three types of orthodromic responses were observed: excitatory, inhibitory, and complex. Priming the animals with 5 μg estradiol benzoate (EB) 48 hr prior to recording had no effect on the overall number of neurons responding to septal area stimulation, but EB priming did significantly reduce the percentage of orthodromically excited neurons. The firing rate of the majority of amygdala neurons responsive to septal area stimularion was not affected by iontophoretically applied LHRH (59 of 76) or LHRH fragment (41 of 65). In some cases, application of LHRH (10 of 76) or Ac‐LHRH5‐10 (12 of 55) produced a change in neuronal firing that was similar in direction to the orthodromically evoked response. When applied during the collection of peristimulus time histograms, both peptides were also able to modulate the orthodromically evoked response (five of 18 cells tested with LHRH and three of 14 cells tesed with Ac‐LHRH5‐10). The results demonstrate a large projection from the septal area to the amygdala, one component of which is altered by estrogen priming. The findings suggest that LHRH released from septal neurons may act as a neurotransmitter and a neuromodulator in the medial amygdala; however, the large number of neurons unaffected by the decapeptide indicates that the role of LHRH at this synapse is subservient to that of another tranmitter (s).
AB - Medial amygdala neurons responsive to electrical stimulationof the medial septal area were electrophysiologically identified in ovariectomized, urethane‐anesthetized female rats. Peristimulus time histograms were collected and used to define the orthodromic response. The action of iontophoretically applied luteinzing hormone‐releasing hormone (LHRH) and an LHRH fragment, Ac‐LHRH5–10, on the activity of were identified as orthodromically responsive. Three types of orthodromic responses were observed: excitatory, inhibitory, and complex. Priming the animals with 5 μg estradiol benzoate (EB) 48 hr prior to recording had no effect on the overall number of neurons responding to septal area stimulation, but EB priming did significantly reduce the percentage of orthodromically excited neurons. The firing rate of the majority of amygdala neurons responsive to septal area stimularion was not affected by iontophoretically applied LHRH (59 of 76) or LHRH fragment (41 of 65). In some cases, application of LHRH (10 of 76) or Ac‐LHRH5‐10 (12 of 55) produced a change in neuronal firing that was similar in direction to the orthodromically evoked response. When applied during the collection of peristimulus time histograms, both peptides were also able to modulate the orthodromically evoked response (five of 18 cells tested with LHRH and three of 14 cells tesed with Ac‐LHRH5‐10). The results demonstrate a large projection from the septal area to the amygdala, one component of which is altered by estrogen priming. The findings suggest that LHRH released from septal neurons may act as a neurotransmitter and a neuromodulator in the medial amygdala; however, the large number of neurons unaffected by the decapeptide indicates that the role of LHRH at this synapse is subservient to that of another tranmitter (s).
KW - Electrical stimulation
KW - LHRH fragment
KW - LHRH receptors
KW - Neuromodulator
KW - Neurotransmitter
KW - Orthodromic response
KW - Synapse
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U2 - 10.1002/syn.890060207
DO - 10.1002/syn.890060207
M3 - Article
C2 - 2237779
AN - SCOPUS:0025099925
SN - 0887-4476
VL - 6
SP - 161
EP - 168
JO - Synapse
JF - Synapse
IS - 2
ER -