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Hypothalamic Modulation of Adrenal Sympathetic Nerve Activity and the Glucose Counter‐Regulatory Response: Involvement of Medullary and Spinal Glutamate Receptors
Author(s) -
Sabetghadam Azadeh,
Korim Willian,
LlewellynSmith Ida,
Verberne Anthony
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.828.3
Subject(s) - glutamate receptor , medullary cavity , adrenal medulla , receptor , endocrinology , neuroscience , medicine , chemistry , biology , catecholamine
The rostral ventrolateral medulla (RVLM) and perifornical hypothalamus (PeF) control adrenaline release during the glucose counter‐regulatory response (GCRR) but the circuitry is not well‐defined. In anesthetised rats, we measured ASNA after RVLM or PeF electrical stimulation (0.5Hz, 50‐400µA, 1ms). We gave intrathecal kynurenate (KYN; 5µmol/10μl) or vehicle before stimulation and 2‐deoxyglucose (2‐DG) iv or into PeF after KYN or vehicle into RVLM. Hexamethonium (hex; 20‐40mg/kg iv) discriminated pre‐ and post‐ganglionic ASNA responses. In other rats, we injected the tracer CTB into the adrenal medulla and immunoperoxidase stained cord sections for CTB+orexin. After RVLM stimulation, ASNA showed pre‐ or post‐ganglionic early peaks (63±3 ms; 56±6 ms) and pre‐ or post‐ganglionic late peaks (132±7 ms; 139±4 ms). Intrathecal KYN reduced all peaks ( P <0.05). After PeF stimulation, ASNA consisted of pre‐ or post‐ganglionic early peaks (84±1 ms; 91±1 ms) and pre‐ or post‐ganglionic late peaks (133±2 ms; 143±2 ms). Hex reduced or abolished all RVLM‐evoked peaks but only the PeF‐evoked early peak ( P <0.05). KYN in RVLM (5nmol/100nl) reduced ( P <0.05) ASNA after iv and PeF 2‐DG. Orexin terminals apposed sympathoadrenal neurons in the spinal cord. These data implicate a monosynaptic PeF‐spinal pathway, long latency pre‐ganglionic responses and orexin input in control of adrenaline release. Glutamatergic circuits including PeF, RVLM and spinal cord may underpin the GCRR.