title: Gap Junctions Contribute to Ictal/Interictal Genesis in Human Hypothalamic Hamartomas.
abstract: Human hypothalamic hamartoma (HH) is a rare subcortical lesion associated with treatment-resistant epilepsy. Cellular mechanisms responsible for epileptogenesis are unknown. We hypothesized that neuronal gap junctions contribute to epileptogenesis through synchronous activity within the neuron networks in HH tissue. We studied surgically resected HH tissue with Western-blot analysis, immunohistochemistry, electron microscopy, biocytin microinjection of recorded HH neurons, and microelectrode patch clamp recordings with and without pharmacological blockade of gap junctions. Normal human hypothalamus tissue was used as a control. Western blots showed increased expression of both connexin-36 (Cx36) and connexin-43 (Cx43) in HH tissue compared with normal human mammillary body tissue. Immunohistochemistry demonstrated that Cx36 and Cx43 are expressed in HH tissue, but Cx36 was mainly expressed within neuron clusters while Cx43 was mainly expressed outside of neuron clusters. Gap-junction profiles were observed between small HH neurons with electron microscopy. Biocytin injection into single recorded small HH neurons showed labeling of adjacent neurons, which was not observed in the presence of a neuronal gap-junction blocker, mefloquine. Microelectrode field recordings from freshly resected HH slices demonstrated spontaneous ictal/interictal-like discharges in most slices. Bath-application of gap-junction blockers significantly reduced ictal/interictal-like discharges in a concentration-dependent manner, while not affecting the action-potential firing of small gamma-aminobutyric acid (GABA) neurons observed with whole-cell patch-clamp recordings from the same patient's HH tissue. These results suggest that neuronal gap junctions between small GABAergic HH neurons participate in the genesis of epileptic-like discharges. Blockade of gap junctions may be a new therapeutic strategy for controlling seizure activity in HH patients.
authors.affiliation: The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China; Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA; Department of Pharmacology, Shantou University of Medical College, Guangdong, Shantou 815041, China. Electronic address: jie.wu@dignityhealth.org.
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
authors.affiliation: Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Gao
authors.affiliation: Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Rice
authors.affiliation: Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA.
authors.forename: Candy
authors.initials: C
authors.lastname: Tsang
authors.affiliation: Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: John
authors.initials: J
authors.lastname: Beggs
authors.affiliation: Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Dharshaun
authors.initials: D
authors.lastname: Turner
authors.affiliation: Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Guohui
authors.initials: G
authors.lastname: Li
authors.affiliation: The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.affiliation: The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China; Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Kunkun
authors.initials: K
authors.lastname: Xia
authors.affiliation: Department of Pharmacology, Shantou University of Medical College, Guangdong, Shantou 815041, China.
authors.forename: Fenfei
authors.initials: F
authors.lastname: Gao
authors.affiliation: Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ 85004, USA.
authors.forename: Shenfeng
authors.initials: S
authors.lastname: Qiu
authors.affiliation: Division of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: Kerrigan
mesh_terms: D000293:Adolescent; D000328:Adult; D002229:Carbenoxolone / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D017630:Connexins / Q000235:genetics / Q000378:metabolism; D055724:Electrophysiological Phenomena; D004827:Epilepsy / Q000209:etiology* / Q000378:metabolism*; D005260:Female; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D015870:Gene Expression; D006222:Hamartoma / Q000150:complications* / Q000378:metabolism* / Q000601:surgery; D006801:Humans; D007027:Hypothalamic Diseases / Q000150:complications* / Q000378:metabolism* / Q000601:surgery; D007223:Infant; D008297:Male; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D055815:Young Adult
chemical_list: D017630:Connexins; D002229:Carbenoxolone
keywords: Gap junction; Gelastic seizures; Human epilepsy; Hypothalamic hamartoma; Patch-clamp