Possible brain regions involved in parturition in mice.

The spinal and peripheral innervation of the clitoris and vagina are fairly well understood. However, little is known regarding supraspinal control of these pelvic structures. The multisynaptic tracer pseudorabies virus (PRV) was used to map the brain neurons that innervate the clitoris and vagina. To delineate forebrain input on PRV-labeled cells, the anterograde tracer biotinylated dextran amine was injected in the medial preoptic area (MPO), ventromedial nucleus of the hypothalamus (VMN), or the midbrain periaqueductal gray (PAG) 10 days before viral injections. These brain regions have been intimately linked to various aspects of female reproductive behavior. After viral injections (4 days) in the vagina and clitoris, PRV-labeled cells were observed in the paraventricular nucleus (PVN), Barrington's nucleus, the A5 region, and the nucleus paragigantocellularis (nPGi). At 5 days postviral administration, additional PRV-labeled cells were observed within the preoptic region, VMN, PAG, and lateral hypothalamus. Anterograde labeling from the MPO terminated among PRV-positive cells primarily within the dorsal PVN of the hypothalamus, ventrolateral VMN (VMNvl), caudal PAG, and nPGi. Anterograde labeling from the VMN terminated among PRV-positive cells in the MPO and lateral/ventrolateral PAG. Anterograde labeling from the PAG terminated among PRV-positive cells in the PVN, ventral hypothalamus, and nPGi. Transynaptically labeled cells in the lateral hypothalamus, Barrington's nucleus, and ventromedial medulla received innervation from all three sources. These studies, together, identify several central nervous system (CNS) sites participating in the neural control of female sexual responses. They also provide the first data demonstrating a link between the MPO, VMNvl, and PAG and CNS regions innervating the clitoris and vagina, providing support that these areas play a major role in female genital responses.

Unravelling the neural circuitry for circadian regulation of sleep–wake cycles

In the present investigations the viral transneuronal labeling method, which is able to reveal hierarchial chains of central nervous system (CNS) neurons, was applied to identify sites in the CNS connected with the ovary and presumably involved in the control of ovarian functions. Pseudorabies virus was injected into the ovaries of rats and a few days later (at various times after the injection) the spinal cord and brain were examined for virus-infected neurons from the ovary. The virus-labeled nerve cells were identified by immunocytochemistry using polyclonal antiviral antibody. Virus-labeled neurons were detected both in the spinal cord and the brain. In the spinal cord such elements were observed in the intermediolateral cell column, in the dorsal horn close to the marginal zone and in the central autonomic nucleus. In the medulla oblongata and pons, neurons of several nuclei and cell groups (area postrema, nucleus of the solitary tract, dorsal vagal complex, nucleus ambiguus, paragigantocellular nucleus, parapyramidal nucleus, A1, A5 and A7 cell groups, caudal raphe nuclei, locus ceruleus, subceruleus nucleus, Barrington’s nucleus, Kölliker-Fuse nucleus) were found to be transneuronally labeled. In the mesencephalon, the ventrolateral part of the periaqueductal gray matter contained virus-labeled neurons. In the diencephalon, a very intensive cell body labeling was observed in the hypothalamic paraventricular nucleus and a few virus-infected neurons could be detected in the lateral and dorsal hypothalamus, in the arcuate nucleus, zona incerta, perifornical area and in the anterior hypothalamus. Concerning the telencephalic structures, virus-labeled cells were found in the bed nucleus of the stria terminalis and in the central amygdala nucleus. These findings provide the first neuromorphological evidence for the existence of a multisynaptic neuronal pathway between the ovary and the CNS, and give a detailed account of the structures involved in this pathway.

Arcuate NPY Controls Sympathetic Output and BAT Function via a Relay of Tyrosine Hydroxylase Neurons in the PVN

Gastrin-releasing peptide mediated regulation of 5-HT neuronal activity in the hypothalamic paraventricular nucleus under basal and restraint stress conditions

The autonomic network of the central nervous system (CNS) play an important role in the regulation of many physiological functions. Obesity is often associated with hypertension which is a serious medical condition that increase mortality. Therefore, obesity-induced hypertension may be the consequence of a cardiovascular-metabolic coupling in the CNS autonomic network. Leptin, a hormone secreted by adipose tissue, acts in the brain to regulate energy homeostasis, cardiovascular function, and several other physiological processes. We and others have previously shown the existence of shared nuclei in the autonomic network innervating organs such as the kidney, liver, and brown adipose tissue (BAT). However, whether there are shared neurons within these nuclei associated with these three organs and the anatomical substrates underlying cardiovascular and metabolic control by the leptin receptor (LepR)-containing neurons are unknown. To address this, two groups of wildtype mice received injections of pseudorabies virus (PRV) expressing a green fluorescent protein (GFP) into both kidneys and PRV expressing a red fluorescent protein (RFP) in either the interscapular BAT (iBAT) or the left lobe of the liver. Additionally, mice bearing Cre-mediated expression of a fluorescent protein, td-Tomato, in LepR neurons were injected with PRV in either the kidneys, liver, or iBAT. The animals were sacrificed 5-7 days post-injection and perfused. The brains were extracted, sectioned at 50 μm thickness, stained, and imaged with confocal microscopy. Sections were matched to the mouse brain atlas (Franklin & Paxinos) and neurons co-expressing GFP and RFP throughout the brain were identified. For the double-organ injections, soma morphology was measured using ImageJ software. We found several nuclei in which neurons were co-labeled with GFP (kidney) and RFP (BAT or liver). Co-expressing neurons were observed in areas such as the cortical regions (motor cortex and amygdala), hypothalamus (paraventricular nucleus (PVN), lateral hypothalamus (LH), and dorsomedial hypothalamus (DMH)), midbrain regions such as the periaqueductal gray, and brainstem nuclei such as the locus coeruleus (LC). In general, there appeared to be two scenarios for shared nuclei: 1) in regions such as LH, nucleus of the solitary tract, and dorsal motor nucleus of vagus there was little to very little co-expression, and 2) in regions such as PVN, DMH, LC, and motor cortex there was moderate to high levels of co-expression. Using the Kolmogorov-Smirnov test the kidney and iBAT soma sizes for the PVN, motor cortex, and LC were statistically different (p<0.05), but not for the LH (p>0.1). Approximately 5% of LepR neurons in the lateral hypothalamic area, septal nucleus, ventral tegmental area, and nucleus tractus solitarius (nTS) were linked to kidney or iBAT. Many other common nuclei between the organ associated regions and LepR neurons such as the amygdala and dorsal-medial hypothalamus did not appear to demonstrate any co-localization. This is the first study to provide anatomical evidence linking the autonomic networks regulating cardiovascular and metabolic functions. Moreover, our data show that although there is overlap of neurons in diverse nuclei there may also be a difference in morphological phenotype in the nuclei associated with cardiovascular vs metabolic functions. Our results suggest that leptin may couple cardiovascular and metabolic regulation through a small number of neurons in the CNS autonomic network. Renal & Hypertension T32 (DK007690), American Heart Association (834962), and Diabetes T32 (DK112751). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

CNS cell groups projecting to the submandibular parasympathetic preganglionic neurons in the rat: a retrograde transneuronal viral cell body labeling study

Percutaneous cordotomy for malignant pain

Periaqueductal gray matter input to cardiac-related sympathetic premotor neurons

Despite considerable interest in the neural mechanisms that regulate muscle blood flow, the descending pathways that control sympathetic outflow to skeletal muscles are not adequately understood. The present study mapped these pathways through the transneuronal transport of two recombinant strains of pseudorabies virus (PRV) injected into the gastrocnemius muscles in the left and right hindlimbs of rats: PRV-152 and PRV-BaBlu. To prevent PRV from being transmitted to the brain stem via motor circuitry, a spinal transection was performed just below the L2 level. Infected neurons were observed bilaterally in all of the areas of the brain that have previously been shown to contribute to regulating sympathetic outflow: the medullary raphe nuclei, rostral ventrolateral medulla (RVLM), rostral ventromedial medulla, A5 adrenergic cell group region, locus coeruleus, nucleus subcoeruleus, and the paraventricular nucleus of the hypothalamus. The RVLM, the brain stem region typically considered to play the largest role in regulating muscle blood flow, contained neurons infected following the shortest postinoculation survival times. Approximately half of the infected RVLM neurons were immunopositive for tyrosine hydroxylase, indicating that they were catecholaminergic. Many (47%) of the RVLM neurons were dually infected by the recombinants of PRV injected into the left and right hindlimb, suggesting that the central nervous system has a limited capacity to independently regulate blood flow to left and right hindlimb muscles.

The lordosis reflex is a hormone-dependent behavior displayed by female rats during mating. This study used the transneuronal tracer pseudorabies virus (PRV) to investigate the CNS network that controls the lumbar epaxial muscles that produce this posture. After PRV was injected into lumbar epaxial muscles, the time course analysis of CNS viral infection showed progressively more PRV-labeled neurons in higher brain structures after longer survival times. In particular, the medullary reticular formation, periaqueductal gray (PAG), and ventromedial nucleus of the hypothalamus (VMN) were sequentially labeled with PRV, which supports the proposed hierarchical network of lordosis control. Closer inspection of the PRV-immunoreactive neurons in the PAG revealed a marked preponderance of spheroid neurons, rather than fusiform or triangular morphologies. Furthermore, PRV-immunoreactive neurons were concentrated in the ventrolateral column, rather than the dorsal, dorsolateral, or lateral columns of the PAG. Localization of the PRV-labeled neurons in the VMN indicated that the majority were located in the ventrolateral subdivision, although some were also in other subdivisions of the VMN. As expected, labeled cells also were found in areas traditionally associated with sympathetic outflow to blood vessels and motor pathways, including the intermediolateral nucleus of the spinal cord, the paraventricular hypothalamic nucleus, the red nucleus, and the motor cortex. These results suggest that the various brain regions along the neuraxis previously implicated in the lordosis reflex are indeed serially connected.

Neuroanatomical Evidence for a Role of Central Melanocortin-4 Receptors and Oxytocin in the Efferent Control of the Rodent Clitoris and Vagina

This review summarizes our recent studies using the viral transneuronal tracing technique to identify sites in the central nervous system (CNS) that are connected with the ovary. A neurotropic virus (pseudorabies virus) was injected into the ovary and various times after the inoculation the spinal cord and brain were examined for virus-infected neurons identified by immunocytochemistry. Such neurons could be detected in well-defined cell groups of the spinal cord (intermediolateral cell column), brain stem (vagal nuclei, area postrema, parapyramidal nucleus, caudal raphe nuclei, A1, A5, A7 noradrenergic cell groups, locus coeruleus, Barrington's nucleus, periaqueductal gray), hypothalamus (paraventricular nucleus, anterior hypothalamus, arcuate nucleus, zona incerta), and, at longer survival time, in some telencephalic structures (amygdala, bed nucleus of the stria terminalis). These findings provided the first neuromorphological evidence for the existence of a multisynaptic neuronal pathway between the brain and the ovary presumably involved in the neuronal control of the organ. The observations indicate that there is a significant overlap of CNS structures connected with the ovary, the testis, other organs and organ systems, suggesting similar neuronal circuitries of the autonomic nervous system innervating the different organs. The known descending neuronal connections between the CNS structures labeled from the ovary by the viral transneuronal tracing technique and the findings suggesting a pituitary independent interplay between certain cerebral structures such as the hypothalamus, the amygdala, and the ovary are also summarized in this review.

Ginkgo biloba extract enhances noncontact erection in rats: the role of dopamine in the paraventricular nucleus and the mesolimbic system

Microglia activation in the hypothalamic PVN following myocardial infarction