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Networking of glucagon-like peptide-1 axons with GnRH neurons in the basal forebrain of male mice revealed by 3DISCO-based immunocytochemistry and optogenetics

Vastagh, Csaba and Farkas, Imre and Scott, Michael M. and Liposits, Zsolt (2021) Networking of glucagon-like peptide-1 axons with GnRH neurons in the basal forebrain of male mice revealed by 3DISCO-based immunocytochemistry and optogenetics. BRAIN STRUCTURE & FUNCTION, 226. pp. 105-120. ISSN 1863-2653 (print); 1863-2661 (online)

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Abstract

Glucagon-like peptide-1 (GLP-1) regulates reproduction centrally, although, the neuroanatomical basis of the process is unknown. Therefore, the putative networking of the central GLP-1 and gonadotropin-releasing hormone (GnRH) systems was addressed in male mice using whole mount immunocytochemistry and optogenetics. Enhanced antibody penetration and optical clearing procedures applied to 500-1000 µm thick basal forebrain slices allowed the simultaneous visualization of the two distinct systems in the basal forebrain. Beaded GLP-1-IR axons innervated about a quarter of GnRH neurons (23.2 ± 1.4%) forming either single or multiple contacts. GnRH dendrites received a more intense GLP-1 innervation (64.6 ± 0.03%) than perikarya (35.4 ± 0.03%). The physiological significance of the innervation was examined by optogenetic activation of channelrhodopsin-2 (ChR2)-expressing axons of preproglucagon (GCG) neurons upon the firing of GnRH neurons by patch clamp electrophysiology in acute brain slices of triple transgenic mice (Gcg-cre/ChR2/GFP-GnRH). High-frequency laser beam stimulation (20 Hz, 10 ms pulse width, 3 mW laser power) of ChR2-expressing GCG axons in the mPOA increased the firing rate of GnRH neurons (by 75 ± 17.3%, p = 0.0007). Application of the GLP-1 receptor antagonist, Exendin-3-(9-39) (1 μM), prior to the photo-stimulation, abolished the facilitatory effect. In contrast, low-frequency trains of laser pulses (0.2 Hz, 60 pulses) had no effect on the spontaneous postsynaptic currents of GnRH neurons. The findings indicate a direct wiring of GLP-1 neurons with GnRH cells which route is excitatory for the GnRH system. The pathway may relay metabolic signals to GnRH neurons and synchronize metabolism with reproduction.

Item Type: Article
Uncontrolled Keywords: Glucagon-like peptide-1; GnRH neuron; Neuronal networking; 3DISCO; Optogenetics; Slice electrophysiology; Patch clamp; Transgenic mice
Subjects: R Medicine / orvostudomány > R1 Medicine (General) / orvostudomány általában > R850-854 Experimental medicine / kisérleti orvostudomány
R Medicine / orvostudomány > RC Internal medicine / belgyógyászat > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry / idegkórtan, neurológia, pszichiátria
SWORD Depositor: MTMT SWORD
Depositing User: MTMT SWORD
Date Deposited: 06 Jul 2021 11:43
Last Modified: 06 Jul 2021 11:43
URI: http://real.mtak.hu/id/eprint/127318

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