ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
A nucleated structure (divisible into MEDIAL and lateral preoptic nucleus and the SEXUALLY DIMORPHIC NUCLEUS OF THE PREOPTIC AREA) with input from the NUCLEUS ACCUMBENS, AMYGDALA and SEPTAL NUCLEI and output to the HYPOTHALAMUS, amygdala, SUBSTANTIA NIGRA, VENTRAL TEGMENTAL AREA and several parts of the BRAINSTEM, including LOCUS COERULEUS, CUNEIFORM NUCLEUS, RAPHE NUCLEI, PARABRACHIAL NUCLEI and CENTRAL GREY. The preoptic area is difficult to position. Some authors consider it to be an anterior part of the HYPOTHALAMUS and include the SUPRACHIASMATIC NUCLEUS within it, while others consider that the preoptic area is anterior to the hypothalamus, not in it. Although the preoptic area blends into adjacent structures (such as the anterior hypothalamus and BED NUCLEUS OF THE STRIA TERMINALIS), developmental evidence suggests that it is an independent entity, the PRIMORDIUM being in the FOREBRAIN, cells migrating to their final position at the border of the TELENCEPHALON and DIENCEPHALON. Functionally, the preoptic area is associated with motivated behaviours such as DRINKING (lesions in the lateral preoptic area affect responding to PHYSIOLOGICAL CHALLENGE or dehydration), SEXUAL BEHAVIOUR (the sexually dimorphic nucleus of the preoptic area [in the medial part of the preoptic area] is larger in males than females—see SEX DIFFERENCES; SEXUAL DIMORPHISM) and THERMOREGULATION (there are neurons whose activity reflects body temperature here).
Neuroendocrine Morphology
Paul V. Malven in Mammalian Neuroendocrinology, 2019
Other components of the limbic system include the septum, olfactory gray, and parts of the cerebral cortex (i.e., cingulate gyrus and hippocampal gyrus). The epithalamus and its associated pineal gland should probably be considered functionally part of the limbic system although they were not included in the original designation. Finally, the hypothalamus is the part of the limbic system most intimately involved with neuroendocrinology. Not only does it contain perikarya of neurons which participate in neuroendocrine regulation and integration, but it contains many tracts which connect with other parts of the limbic system. The preoptic area is included herein as a functional part of the hypothalamus although morphological classifications often list the preoptic area as a separate entity. The major fiber pathways connecting the hypothalamus with limbic and non-limbic structures are depicted in Figure 2-3 in a schematic and highly simplified diagram.
Sleep Disorders
Divya Vohora in The Third Histamine Receptor, 2008
During the active period, orexin is synthesized by a cluster of neurons within the posterior lateral hypothalamus as prepro-orexin peptide that is eventually cleaved by the enzyme convertase that liberates two peptides, orexin-A and orexin-B. Orexin-A can bind to either the G-protein-coupled orexin-1 or orexin-2 receptor, whereas orexin-B has only an affinity for the orexin-2 receptor. These receptors have specific localizations within areas of the brain that regulate sleep and wake including the TMN (orexin-2), LC (orexin-1), or the raphe, LDT, PPT that express both the orexin-1 and orexin-2 receptors. The result of orexin activation of these postsynpatic receptors is the release of wake-promoting neurotransmitters (i.e., histamine, acetylcholine, serotonin, norepinephrine) [31–33]. In turn, the release of these neurotransmitters inhibits the activity of the sleep centers within a distinct region of the lateral preoptic area of the hypothalamus termed the ventral lateral preoptic (VLPO) area [1,33].
Genetic identification of preoptic neurons that regulate body temperature in mice
Published in Temperature, 2022
Natalia L. S. Machado, Clifford B. Saper
Lesion studies in the early 1900s identified the preoptic area of the hypothalamus (POA) as a center for thermoregulatory control[1]. One of these studies by Ranson in 1930 demonstrated that lesions in the POA led to a hyperthermic response or “fever” in the absence of an inflammatory signal in monkeys, cats, and rodents [2]. Other studies showed that artificial warming of the POA triggers body cooling by activating heat defense mechanisms [3]. Single-cell recordings by Boulant identified thermoresponsive neurons (defined as an increase of firing by more than 0.8 spikes per second per degree C of warming or cooling) throughout a broad region of the POA[1]. In whole animals, individual neurons responded both to local warming as well as to skin warming, indicating convergence of these inputs [4]. Hammel and colleagues identified also cold-sensing neurons in the POA, which were thought to mediate non-shivering thermogenesis, shivering, cutaneous vasoconstriction, and behavioral responses to cooling of the POA [5]. Together, these studies implicated the POA as a critical site for regulating body temperature (Tb). However, the specific preoptic neurons and the synaptic mechanisms of thermoregulation have been more difficult to elucidate.
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].
Related Knowledge Centers
- Anterior Commissure
- Median Preoptic Nucleus
- Mucous Membrane
- Nucleus
- Thermoreceptor
- Thermoregulation
- Thirst
- Norepinephrine
- Hypothalamus
- Medical Subject Headings