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The Limbic System
Published in Jay A. Goldstein, Chronic Fatigue Syndromes, 2020
Hippocampus. Although the hippocampus receives afferents from numerous structures, its efferents are generally considered to be in the fornix, which terminates in the mammillary body. There are also direct hippocampal efferents to the amygdala and septum. Via the fornix, there are indirect projections to the medial preoptic area, the anterior hypothalamus, the lateral hypothalamic area, the ventral tegmental area, and the central gray matter of the midbrain.12 The mammillary body has diffuse projections in the brain. Hippocampal efferents are said to reach widespread areas of the cerebral cortex and amygdala in the rhesus monkey. These fibers cross to the contralateral limbic zone through commissures, as is true for those of the amygdala and piriform cortex. Mirror images of unilateral limbic lesions have been reported in the contralateral hemisphere. Although the hippocampus has been implicated in emotion and neuro-immune-endocrine regulation, its main function is in the making of memories, and in this mode virtually its entire sensory input is paralimbic. Because of this connection, there is a distinct motivational component to learning. Anxiety may be mediated in the dorsal hippocampus through the septo-hippocampal circuit, since both diazepam and tandospirone, a 5HT 1A agonist, have anti-anxiety effects when injected into the dorsal hippocampus.13 The hippo-campus may also be involved in depression, particularly in elderly depressed patients, in whom magnetic resonance imaging (MM) revealed significantly shortened Ti spin lattice relaxation times.14
Endocrine Functions of Brain Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
Studies with rodents have shown that DA affects the expression of typical maternal behavior in mothers who have given birth, as well as in non-mothers who exhibit maternal behaviors because of repeated exposure to young. Most research has focused on the mesolimbic DA projections from the VTA to the NAc in the ventral striatum [86]. DA is released in the NAc during maternal behavior, and the increased DA release is associated with stronger maternal responses. The medial preoptic area (MPOA) is important for the motivational aspects of maternal behavior. MPOA lesions reduce NAc activity during maternal behavior. Moreover, inhibition of D1R in both the NAc and the MPOA disrupts maternal behavior, whereas stimulation of D1R in the NAc facilitates maternal behavior. DA seems to be especially important for active, goal-directed maternal behaviors, such as pup retrieval, licking, and grooming, and appears to be less important for more passive behaviors such as nursing.
Sexual consequences of multiple sclerosis and other central nervous system disorders
Published in Jacques Corcos, David Ginsberg, Gilles Karsenty, Textbook of the Neurogenic Bladder, 2015
Maarten Albersen, Dirk De Ridder
In men, ED is the most prevailing sexual symptom and occurs in approximately 63% of patients. The parasympathetic penile innervation comprises the major excitatory input to the penis responsible for vasodilation of the penile vasculature and erection. Preganglionic fibers originate in the sacral parasympathetic nucleus (SPN). Thus, lower spinal cord lesions can interfere with the parasympathetic innervation of the corpora and thus result in a lack of bioavailable nitric oxide (NO, the main proerectile neurotransmitter) from penile nerve terminals. Besides, hypothalamic lesions can affect the mainly oxytoninergic and dopaminergic neurons in the medial preoptic area (MPOA), thus disturbing erectile pathways in a supraspinal locus.
Impact of COVID 19 on erectile function
Published in The Aging Male, 2022
D. H. Adeyemi, A. F. Odetayo, M. A. Hamed, R. E. Akhigbe
The process that culminates in penile erection entails a mix of several physiological conditions that border on the input from both central and peripheral nervous systems. Besides, there are a series of the interplay between several biological mediators, vasoactive agents, neurotransmitters, and endocrine agents to achieve the optimal erection necessary for sexual intercourse [48]. The central processing unit in response to tactile, visual, and imaginative stimuli enhances penile erection. In other words, the central and peripheral control systems remain the two major established pathways that regulate or control penile erection. Stimulations of the peripheral tissues involved in erection elicit the response that is controlled by spinal and somatic activities. In addition, evidence from animal studies has suggested that the central control of sexual arousal or erection is predominantly localized in the limbic system structures. The medial preoptic area, paraventricular nucleus, medial amygdala, nucleus acumens, ventral tegmental area, and hippocampus are primary structures in the regulation of male sexual response [49]. Subsequently, a spinal network consisting of primary afferent signals emanating from the genitals, spinal interneurons, sympathetic, parasympathetic, and somatic nuclei are responsible for integrating signals from the periphery thus eliciting reflexive erections [50].
Sexual dysfunction with major depressive disorder and antidepressant treatments: impact, assessment, and management
Published in Expert Opinion on Drug Safety, 2022
Joan Winter, Kimberly Curtis, Bo Hu, Anita H. Clayton
Serotonin binding at the post-synaptic 5-HT1A receptor produces antidepressant and anxiolytic effects, while increased binding at the 5-HT2A and 5-HT2C receptors leads to increased anxiety, insomnia, and sexual dysfunction. Multiple antidepressants (eg. mirtazapine, trazodone, several TCAs, and norquetiapine – the active metabolite of quetiapine) with fewer sexual side effects exhibit antagonism at 5-HT2. The release of dopamine and norepinephrine in the cortex is inhibited by stimulation of 5-HT2A and 5-HT2C receptors [9–10]. Norepinephrine and nitric oxide promote tumescence of sexual organs and lubrication. Dopamine is a key neurotransmitter of the reward system, which includes the nucleus accumbens/ventral striatum, ventral tegmental area (VTA), pre-frontal cortex, orbitofrontal cortex, anterior cingulate cortex, and amygdala. Dopamine promotes sexual function at varying concentrations at progressive stages of sexual engagement: from sexual desire to increased parasympathetic activation required for erections, and finally climax. Dopamine may also be involved in the medial preoptic area of the hypothalamus (mPOA) in the initial disinhibition of genital reflexes[12]. In addition to central effects, serotonin acts in the peripheral nervous system by directly suppressing spinal ejaculatory centers [10–11]. Thus, the increase of serotonin at the synaptic cleft as a result of antidepressant action can impact many levels of sexual functioning: decreased interest and arousal, inhibited/delayed orgasm, and diminished intensity and frequency of orgasm[13].
Hypertension linked to allostatic load: from psychosocial stress to inflammation and mitochondrial dysfunction
Published in Stress, 2019
Feres José Mocayar Marón, León Ferder, Fernando Daniel Saraví, Walter Manucha
When a stimulus is perceived as "noxious", a signal is triggered by the limbic system to the paraventricular nucleus of the hypothalamus (PVN) (Myers, McKlveen, & Herman, 2012). The PVN, a fundamental structure for autonomic and endocrine regulation, is composed of several types of neurons (Pyner, 2009). Among them are magnocellular (which synthesize vasopressin and oxytocin to be released from the posterior hypophysis), the parvocellular neuroendocrine neurons that secrete hypophysiotrophic hormones (like corticotrophin-releasing hormone CRH and vasopressin) and the parvocellular pre-autonomic neurons that control sympathetic nerve activity (neurons projecting to either medullary – NTS and rostral ventrolateral medulla – or spinal – intermediolateral cell column – autonomic control centers) (Yang & Coote, 2007). Included in the excitatory inputs of the PVN are; the dorsal raphe, the tuberomammillary nucleus, the supramammillary nucleus, the subfornical organ, the basolateral amygdala, the infralimbic cortex, the dorsomedial components of the dorsomedial hypothalamus, anterolateral subregions of the BST, the arcuate nucleus and the NTS, among others (Herman, Tasker, Ziegler, & Cullinan, 2002; Myers, Mark Dolgas, Kasckow, Cullinan, & Herman, 2014). Contrariwise, inhibitory inputs are the medial preoptic area, the ventrolateral component of the dorsomedial hypothalamus, the posteromedial subregions of the BST, the ventral subiculum of the hypothalamus, the prelimbic cortex, and local neurons in the peri-PVN region (Ulrich-Lai & Herman, 2009).