Journal: Molecular Metabolism

Article Title: Melanocortin regulation of histaminergic neurons via perifornical lateral hypothalamic melanocortin 4 receptors

doi: 10.1016/j.molmet.2020.01.020

Figure Lengend Snippet: MC4R not MC3R mediates excitation of histaminergic neurons. A) Whole-cell current clamp recording showing THIQ (MC4R selective agonist) induced depolarization and excitation of a HDC neuron. B) THIQ induced a significant depolarization of the membrane potential. C) THIQ induced a significant increase in firing rate. D) Current voltage relationships of a HDC expressing neuron that was excited by THIQ. (THIQ IV was performed with -11.3pA of holding current). E) Plot of data in D demonstrating a decrease in input resistance. Reversal potential averaged across all HDC neurons excited by MTII suggests activation of a nonselective cation conductance. F) Whole-cell current clamp recording showing that [D-Trp8]-γ-MSH (MC3R selective agonist) had no effect on a HDC neuron. G) Summary of the responses to the non-selective and selective melanocortin receptor agonists and combination with various synaptic blockers. H) Immunocytochemistry of a posterior hypothalamic brain slice containing the TMN from a Mc4r -GFP::HDC-Cre::tdTomato mouse. The HDC expressing neurons (red) do not overlap with any of the MC4R (green) expressing neurons, demonstrating no co-expression of MC4R and HDC. Note : // denotes discontinuity in the recording where current voltage relations were performed (67 sec and 34 sec in A and F respectively). ∗p < 0.05, ∗∗p < 0.01.

Article Snippet: The following drugs were used for electrophysiological experiments: MTII (Phoenix Pharmaceuticals), TTX, CNQX, AP5, THIQ, [D-Trp8]-ƴ-MSH, Orexin A (all from Tocris), and clozapine N-oxide (CNO, Sigma).

Techniques: Membrane, Expressing, Activation Assay, Immunocytochemistry, Slice Preparation

Journal: Molecular Metabolism

Article Title: Melanocortin regulation of histaminergic neurons via perifornical lateral hypothalamic melanocortin 4 receptors

doi: 10.1016/j.molmet.2020.01.020

Figure Lengend Snippet: HDC neuron responsiveness to melanocortin receptor agonism did not differ across the TMN∗. HDC neurons that were exposed to selective and non-selective melanocortin receptor agonists (THIQ & MTII) were mapped across the TMN. Response to melanocortin receptor agonism did not reveal any distinct anatomical distribution. A) Bregma -1.70mm where 45% (9/20) of HDC neurons responded to melanocortin receptor agonism and 55% (11/20) were non responsive. B) Bregma -2.06mm where 46% (16/35) of HDC neurons responded to melanocortin receptor agonism and 54% (19/35) were non responsive. C) Bregma -2.46mm where 50% (14/28) of HDC neurons responded to melanocortin receptor agonism and 50% (14/28) were non responsive. D) Bregma -2.80mm where 2/9 (22%) of HDC neurons responded to melanocortin receptor agonism and 78% (7/9) were non-responsive. ∗Image modified from: Mouse Brain: In Stereotaxic Coordinates (3rd ed.). Franklin, K. B. J., & Paxinos, G. Copyright Elsevier (2007).

Article Snippet: The following drugs were used for electrophysiological experiments: MTII (Phoenix Pharmaceuticals), TTX, CNQX, AP5, THIQ, [D-Trp8]-ƴ-MSH, Orexin A (all from Tocris), and clozapine N-oxide (CNO, Sigma).

Techniques: Modification

Journal: Molecular Metabolism

Article Title: Melanocortin regulation of histaminergic neurons via perifornical lateral hypothalamic melanocortin 4 receptors

doi: 10.1016/j.molmet.2020.01.020

Figure Lengend Snippet: Perifornical lateral hypothalamic neurons mediate MTII-induced excitation of HDC neurons. A) Averaged voltage-clamp traces showing that MTII (100nM) enhanced the amplitude of the first constant-latency eEPSC evoked after PeFLH paired-pulse stimulation. B) Absolute increase in the evoked EPSC amplitude of the first response following PeFLH stimulation. C) MTII induced a significant decrease in the paired-pulse ratio (PPR) of eEPSCs recorded in HDC neurons following PeFLH stimulation. D) Whole-cell current clamp recording demonstrating a HDC neuron that was excited by the MC4R agonist THIQ, was also excited by orexin A (200nM). E) The majority of HDC neurons that were responsive to MC4R agonism (THIQ) were also excited by orexin A, whereas only about 50% of HDC neurons that were non-responsive (NR) to MC4R agonism where also excited by orexin A. Numbers of cells are in parentheses. Note : // denotes discontinuity in the recording where current voltage relations were performed (83 sec for THIQ and 45 sec for orexin A). ∗p < 0.05, ∗∗p < 0.01, ns = non significant.

Article Snippet: The following drugs were used for electrophysiological experiments: MTII (Phoenix Pharmaceuticals), TTX, CNQX, AP5, THIQ, [D-Trp8]-ƴ-MSH, Orexin A (all from Tocris), and clozapine N-oxide (CNO, Sigma).

Techniques:

Journal: Scientific Reports

Article Title: α-MSH-induced activation of spinal MC1R but not MC4R enhances colorectal motility in anaesthetised rats

doi: 10.1038/s41598-020-80020-x

Figure Lengend Snippet: Subtypes of MCR responsible for the α-MSH effect. ( a ) Single-stranded cDNA was generated from total RNA isolated from L6-S1 spinal cord tissue using reverse transcriptase (RT +) and amplified using PCR with primer pairs specific for rat Mc1r - Mc5r and Pomc . Amplified products of Mc1r , Mc4r and Pomc were observed in appropriate sizes. The reactions without reverse transcriptase (RT-) were analysed with PCR as a negative control. ( b ) Summarised graph of number of propulsive contractions during a period of 30 min after i.t. of saline, BMS470539 (MC1R agonist, 30 nmol), THIQ (MC4R agonist, 30 nmol) and SHU9119 (MC1R agonist and MC4R antagonist, 3 nmol). BMS470539 and SHU9119, but not THIQ, significantly increased the number of propulsive contractions compared to that in the saline group. Each open circle (○) indicates a result from an individual rat, and the black bar shows the median. *Denotes a significant difference from the saline group ( P < 0.05). Five rats were used in each group.

Article Snippet: Inc., Osaka, Japan), BMS470539 dihydrochloride (Tocris Bioscience, Bristol, UK), THIQ (Santa Cruz Biotechnology, Inc., TX, USA) and SHU9119 (Abcam, Cambridge, UK). α-Chloralose was solubilised with 10% 2-hydroxypropyl-beta-cyclodextrin (Fujifilm Wako Pure Chemical Corp., Osaka, Japan) and then made up with 0.9% saline for infusion.

Techniques: Generated, Isolation, Reverse Transcription, Amplification, Negative Control, Saline