Neuroanatomical characterization of endogenous opioids in the bed nucleus of the stria terminalis.
Numerous neuroanatomical data indicate that the bed nucleus of the stria terminalis (BST) provides an interface between cortical and amygdaloid neurons, and effector neurons modulating motor, autonomic and neuroendocrine responses. Distinct divisions of the BST may be involved in stress response, homeostatic regulation, nociception, and motivated behaviors. Endogenous opioid peptides and receptors are expressed in the BST, but their exact distribution is poorly characterized. The present study used in situ hybridization in order to characterize the endogenous opioid system of the BST, focusing on both enkephalin and dynorphin neuropeptides, as well as their respective receptors (mu, delta, and kappa opioid receptors). We report that preprodynorphin mRNA is observed in distinct nuclei of the BST, namely the fusiform, oval and anterior lateral nuclei. In contrast, there is a widespread expression of preproenkephalin mRNA in both anterior and posterior divisions of the BST. Similarly, mu and kappa opioid receptors are broadly expressed in the BST, whereas delta opioid receptor mRNA was observed only in the principal nucleus. For further characterization of enkephalin-expressing neurons of the BST, we performed a double fluorescent in situ hybridization in order to reveal the coexpression of enkephalin peptides and markers of GABAergic and glutamatergic neurons. Although most neurons of the BST are GABAergic, there is also a modest population of glutamatergic cells expressing vesicular glutamate transporter 2 (VGLUT2) in specific nuclei of the BST. Finally, we identified a previously unreported population of enkephalinergic neurons expressing VGLUT2, which is principally located in the posterior BST.
Poulin
Jean-François
JF
Centre de recherche du CHUQ (CHUL), Neurosciences, Université Laval, Québec, QC, Canada. jean-francois.poulin@crchul.ulaval.ca
Arbour
Danielle
D
Laforest
Sylvie
S
Drolet
Guy
G
D000701:Analgesics, Opioid / Q000378:metabolism*; D000818:Animals; D004745:Enkephalins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D009445:Neuroanatomy / Q000379:methods*; D012333:RNA, Messenger / Q000378:metabolism; D011957:Receptors, Opioid / Q000235:genetics / Q000378:metabolism; D012686:Septal Nuclei / Q000033:anatomy & histology* / Q000378:metabolism*; D050599:Vesicular Glutamate Transport Protein 2 / Q000235:genetics / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000701:Analgesics, Opioid; D004745:Enkephalins; D012333:RNA, Messenger; D011957:Receptors, Opioid; D050599:Vesicular Glutamate Transport Protein 2; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2