Enkephalinergic nerve terminals target inhibitory interneurons in the rat hippocampus

Füzesi, Mária; Rácz, Bence; Eliás, B; Halasy, Katalin

doi:10.1097/00001756-199707280-00012

Cited by 4 publications

(4 citation statements)

References 12 publications

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“…The present results demonstrated that the Enk-IR boutons exclusively formed symmetric contacts, and always on GABAergic postsynaptic structures. This is in contrast with an earlier report about the synapses formed by leu-Enk-IR boutons in the rat CA1 region, where both pyramidal cells and interneurons were found among the postsynaptic elements (Füzesi et al, 1997). This difference may be due to the possibility that the leu-Enk antiserum of Füzesi et al (1997) visualizes boutons of both extrinsic and local origin.…”

Section: Enk-ir Axons In the Ca1 Region Innervate Exclusively Gabaergcontrasting

confidence: 99%

“…1997). This difference may be due to the possibility that the leu‐Enk antiserum of Füzesi et al . (1997) visualizes boutons of both extrinsic and local origin.…”

Section: Discussionmentioning

confidence: 98%

“…Recently, leu-Enk-immunoreactive (IR) fibres were found to contact both pyramidal cells and GABAergic interneurons in the CA1 region of the rat hippocampus (Füzesi et al, 1997), but neither the cells of origin (i.e. local or extrinsic), nor the GABAergic nature of the leu-Enk-IR fibres has been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Enkephalin‐containing interneurons are specialized to innervate other interneurons in the hippocampal CA1 region of the rat and guinea‐pig

Blasco-Ibáñez¹,

Martı́nez-Guijarro²,

Freund³

1998

Eur J of Neuroscience

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Enkephalins are known to have a profound effect on hippocampal inhibition, but the possible endogenous source of these neuropeptides, and their relationship to inhibitory interneurons is still to be identified. In the present study we analysed the morphological characteristics of met-enkephalin-immunoreactive cells in the CA1 region of the rat and guinea-pig hippocampus, their coexistence with other neuronal markers and their target selectivity at the light and electron microscopic levels. Several interneurons in all subfields of the hippocampus were found to be immunoreactive for met-enkephalin. In the guinea-pig, fibres arising from immunoreactive interneurons were seen to form a plexus in the stratum oriens/alveus border zone, and basket-like arrays of boutons on both enkephalin-immunoreactive and immunonegative cell bodies in all strata. Immunoreactive boutons always established symmetric synaptic contacts on somata and dendritic shafts. Enkephalin-immunoreactive cells co-localized GABA, vasoactive intestinal polypeptide and calretinin. Postembedding immunogold staining for GABA showed that all the analysed enkephalin-immunoreactive boutons contacted GABAergic postsynaptic structures. In double-immunostained sections, enkephalin-positive axons were seen to innervate calbindin D28k-, somatostatin-, calretinin- and vasoactive intestinal polypeptideimmunoreactive cells with multiple contacts. Based on these characteristics, enkephalin-containing cells in the hippocampus are classified as interneurons specialized to innervate other interneurons, and represent a subset of vasoactive intestinal polypeptide- and calretinin-containing cells. The striking match of ligand and receptor distribution in the case of enkephalin-mediated interneuronal communication suggests that this neuropeptide may play an important role in the synchronization and timing of inhibition involved in rhythmic network activities of the hippocampus.

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Section: Enk-ir Axons In the Ca1 Region Innervate Exclusively Gabaergcontrasting

confidence: 99%

“…1997). This difference may be due to the possibility that the leu‐Enk antiserum of Füzesi et al . (1997) visualizes boutons of both extrinsic and local origin.…”

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Enkephalin‐containing interneurons are specialized to innervate other interneurons in the hippocampal CA1 region of the rat and guinea‐pig

Blasco-Ibáñez¹,

Martı́nez-Guijarro²,

Freund³

1998

Eur J of Neuroscience

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“…In addition to the sources of heterogeneity described above, there is good evidence that different groups of interneurons are selectively innervated by distinct neurotransmitter-containing afferents (Freund and Antal, 1988;Freund et al, 1990;Fuzesi et al, 1997). Furthermore, different interneurons express distinct sets of neurotransmitter receptors (McBain and Dingledine, 1993;McBain et al, 1994;Bergles et al, 1996;McMahon and Kauer, 1997;Miller et al, 1997;Morales and Bloom, 1997;Frazier et al, 1998;Svoboda and Lupica, 1998), suggesting further segregation of function.…”

mentioning

confidence: 97%

Opioid Receptor Subtype Expression Defines Morphologically Distinct Classes of Hippocampal Interneurons

Svoboda¹,

Adams²,

Lupica

1999

J. Neurosci.

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The inhibition of hippocampal pyramidal cells occurs via inhibitory interneurons making GABAergic synapses on distinct segments of the postsynaptic membrane. In area CA1 of the hippocampus, the activation of mu- and delta-opioid receptors inhibits these interneurons, thereby increasing the excitability of the pyramidal cells. Through the use of selective opioid agonists and biocytin-filled whole-cell electrodes, interneurons possessing somata located within stratum oriens of hippocampal slices were classified according to the location of their primary axon termination and the expression of mu- or delta-opioid receptors. Activation of these opioid receptor subtypes resulted in outward currents in the majority of interneurons, which is consistent with their inhibition. Post hoc morphological analysis revealed that those interneurons heavily innervating the pyramidal cell body layer were much more likely to express mu-opioid receptors, whereas cells with axons ramifying in the pyramidal neuron dendritic layers were more likely to express delta-opioid receptors, as defined by the generation of outward currents. This morphological segregation of interneuron projections suggests that mu receptor activation would diminish GABA release onto pyramidal neuron somata, thereby increasing their excitability and output. Conversely, inhibition of interneurons via delta receptor activation would amplify afferent signaling to pyramidal neuron dendrites by reducing GABAergic inhibition of these structures.

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Kappa opioid receptor is expressed by somatostatin- and neuropeptide Y-containing interneurons in the rat hippocampus

Rácz

Halasy

2002

Brain Research

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Enkephalinergic nerve terminals target inhibitory interneurons in the rat hippocampus

Cited by 4 publications

References 12 publications

Enkephalin‐containing interneurons are specialized to innervate other interneurons in the hippocampal CA1 region of the rat and guinea‐pig

Enkephalin‐containing interneurons are specialized to innervate other interneurons in the hippocampal CA1 region of the rat and guinea‐pig

Opioid Receptor Subtype Expression Defines Morphologically Distinct Classes of Hippocampal Interneurons

Kappa opioid receptor is expressed by somatostatin- and neuropeptide Y-containing interneurons in the rat hippocampus

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