Introduction: Female sexual dysfunction affects approximately 40% of women in the United States, yet few therapeutic options exist for these patients. The melanocortin system is a new treatment target for hypoactive sexual desire disorder (HSDD), but the neuronal pathways involved are unclear.
Methods: In this study, the sexual behavior of female MC4R knockout mice lacking melanocortin 4 receptors (MC4Rs) was examined. The mice were then bred to express MC4Rs exclusively on Sim1 neurons (tbMC4RSim1 mice) or on oxytocin neurons (tbMC4ROxt mice) to examine the effect on sexual responsiveness.
Results: MC4R knockout mice were found to approach males less and have reduced receptivity to copulation, as indicated by a low lordosis quotient. These changes were independent of body weight. Lordosis behavior was normalized in tbMC4R mice and improved in tbMC4R mice. In contrast, approach behavior was unchanged in tbMC4R mice but greatly increased in tbMC4R animals. The changes were independent of melanocortin-driven metabolic effects.
Discussion: These results implicate MC4R signaling in Oxt neurons in appetitive behaviors and MC4R signaling in Sim1 neurons in female sexual receptivity, while suggesting melanocortin-driven sexual function does not rely on metabolic neural circuits.
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http://dx.doi.org/10.3389/fendo.2023.983670 | DOI Listing |
Proc Natl Acad Sci U S A
December 2024
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-000, Brazil.
Growth hormone (GH) has several metabolic effects, including a profound impact on glucose homeostasis. For example, GH oversecretion induces insulin resistance and increases the risk of developing diabetes mellitus. Here, we show that GH receptor (GHR) ablation in vesicular glutamate transporter 2 (VGLUT2)-expressing cells, which comprise a subgroup of glutamatergic neurons, led to a slight decrease in lean body mass without inducing changes in body adiposity.
View Article and Find Full Text PDFAuton Neurosci
November 2024
Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, USA; Tulane Brain Institute, Tulane University, New Orleans, Louisiana, USA. Electronic address:
Sympathetic circuits including pre-sympathetic neurons in the ventrolateral medulla (VLM) and in the paraventricular nucleus (PVN) of the hypothalamus play an important role in the regulation of hepatic glucose metabolism. Despite the importance of central regulatory pathways, specific information regarding the circuits of liver-related neurons is limited. Here, we tested the hypothesis that PVN neurons are directly connected to spinally-projecting liver-related neurons in the VLM of mice.
View Article and Find Full Text PDFElife
October 2024
Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
While considerable progress has been made in understanding the neuronal circuits that underlie the patterning of locomotor behaviours such as walking, less is known about the circuits that amplify motoneuron output to enable adaptable increases in muscle force across different locomotor intensities. Here, we demonstrate that an excitatory propriospinal neuron population (V3 neurons, Sim1 ) forms a large part of the total excitatory interneuron input to motoneurons (∼20%) across all hindlimb muscles. Additionally, V3 neurons make extensive connections among themselves and with other excitatory premotor neurons (such as V2a neurons).
View Article and Find Full Text PDFJ Neuroendocrinol
February 2024
Centre for Neuroendocrinology, Department of Anatomy, University of Otago, Dunedin, New Zealand.
The arcuate nucleus is a crucial hypothalamic brain region involved in regulating body weight homeostasis. Neurons within the arcuate nucleus respond to peripheral metabolic signals, such as leptin, and relay these signals via neuronal projections to brain regions both within and outside the hypothalamus, ultimately causing changes in an animal's behaviour and physiology. There is a substantial amount of evidence to indicate that leptin is intimately involved with the postnatal development of arcuate nucleus melanocortin circuitry.
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