Limbic system hypothalamus

Endorphins are found primarily in the limbic system, hypothalamus, and brainstem. Enkephalins and dynorphin (in smaller quantities) are found primarily in the periaqueductal gray matter (PAG) of the midbrain, the limbic system, and the hypothalamus. These endogenous substances mimic the effects of morphine and other opiate drugs at many points in the analgesic system, including in the dorsal horns of the spinal cord. 

OT receptors are localized ia the brain hypothalamus, limbic system, cortex, striatum, olfactory system, and brain stem. In the periphery, OT is best known for its stimulation of uterine smooth muscle and the milk ejection reflex. Thr , Om ]oxytocin(l—8),... 

Figure 8.1 The pain pathway. The pain signal is transmitted to several regions of the brain, including the thalamus reticular formation hypothalamus limbic system and somatosensory cortex. Each region carries out a specific aspect of the response to pain.

Nerve signals from the thalamus and the reticular formation are transmitted to the limbic system as well as the hypothalamus. Together, these regions of the brain are responsible for behavioral and emotional responses to pain. The limbic system, in particular, may be involved with the mood-altering and attention-narrowing effect of pain. 

IHC shows CYP19 in hypothalamus and limbic system of rat brain (Tsuruo et al., 1994). 

Most of the serotonin in the brain is in the brainstem, specifically in the raphe nuclei considerable amounts also are present in areas of the hypothalamus, the limbic system, and the pituitary gland. Current evidence indicates that serotonin is involved in the regulation of several aspects of behavior, including sleep, pain perception, depression, sexual activity, and aggressiveness. Some of the most important antidepressant agents are believed to prevent the reuptake of serotonin (see Chapter 33). Serotonin also may be involved in temperature regulation and in the hypothalamic control of the release of pituitary hormones. 

Mechanism of Action An isoindole that stimulates the central nervous system and primarily exerting its effect on the limbic system. Therapeutic Effect Stimulates the hypothalamus to reduce appetite. 

Oxytocin, a nine amino acid peptide, is synthesized primarily in the paraventricular and supraoptic (SON) nuclei of the hypothalamus, from which it is released to the general circulation through the posterior pituitary (Insel et ah, 1997). However, oxytocinergic fibers have also been found to project from the PVN to the limbic system and several autonomic centers in the brain stem. This central OT pool appears to be independent of pituitary OT release cerebrospinal fluid (CSF) and plasma OT responses to numerous stimuli are not correlated (Insel, 1997). Oxytocin and its analog (or partner) peptide vasopressin are found only in mammals. A related peptide, vasotocin, thought to be the evolutionary precedent of these peptides, is found in reptiles and birds. The first known actions of OT were its peripheral effects on the physiology of new mothers. In mammals, OT stimulates milk ejection and uterine contraction, essential aspects of maternal physiology (Insel et ah, 1997). 

Kupfermann, Irving. 1991. "Hypothalamus and Limbic System Peptidergic Neurons, Homeostasis, and Emotional Behavior." In Principles of Neural Science, edited by Eric R- Kandel, James H. Schwartz, and Thomas M. Jessell. 3d ed. New York Elsevier. 

And as we ve seen before, what happens after a drug exits the brain tells us something about what parts of the brain were affected under the influence of that drug. With regard to cocaine, these include the arousal systems within the brainstem, the feeding centers within the hypothalamus, and the reward centers within the frontal lobes and limbic system. Thus, cocaine reduces the need for sleep, and its absence produces extreme... 

These areas include the periaqueductal gray region of the spinoreticular tract, medial thalamic nuclei, hypothalamus, limbic system, and several other areas.33,65,75... 

Corticotropin-releasing factor and arginine vasopressin, which are released predominantly by the paraventricular nucleus of the hypothalamus, are important regulators of corticotropin (ACTH) release, which in turn triggers the release of cortisol and other steroids by the adrenal gland. Both the administration of certain psychoactive agents and emotional arousal originating from the limbic system are able to modify the functions of the pituitary-adrenal axis and stimulate the synthesis of cortisol. 

Orexins (also known as hypocretins) and presynaptic receptors activated by orex-ins were first described in 1998 (Figure 1). Orexin-A (hypocretin-1) and orexin-B (hypocretin-2) consist of 33 and 28 amino acid residues, respectively, and are derived from a common precursor molecule (prepro-orexin). They act on two receptors, OXi and OX2. Orexinergic neurones have their perikarya in the lateral and posterior part of the hypothalamus and project to many parts of the brain, including the cerebral cortex, thalamus, limbic system, locus coeruleus and raphe nuclei, and to the spinal cord. Orexin-like immunoreactive neurones also occur in the small intestine (for review, see Smart and Jerman 2002). 

Limbic system detect a gene mutation. The method uses the coupling of two adjacent synthetic oligonucleotides aligned on the template of the target deoxyribonucleic acid (DNA). Area of the brain associated with small, involuntary functions, emotions and behaviour. Comprises the hypothalamus, parahippocampus, olfactory lobe, dentate gyrus, amygdala, anterior thalamus, fornix and stria terminalis. 

Stress-related stimuli probably trigger NE neuronal activity, via the amygdala and PFC afferents. The activation of NE neurons results in an increase in NE transmission in the hypothalamus and limbic system. The increase in NE levels in hypothalamus results in activation of hypothalamus-hypophysis-adrenal (HPA) axis, via a (3-adrenergic receptor-mediated mechanism. An increase in NE in the limbic system stimulates neuronal activity of glutamatergic pyramidal neurons and decreases the firing of GABA basket intemeurons, via a2- and (3-adrenergic mechanisms, respectively. 

Animal testing has also demonstrated that animals exposed once to a high dose of chemicals or to a low dose of chemicals over a long period of time became hypersensitive such that additional exposures to chemicals began to affect the electrical activity in the limbic system. If the hypothalamus is thereby activated, this could explain many of the fundamental symptoms of MCS, because this gland influences the immune system, the central nervous system and the endocrine system (glands, hormones, and so forth). The limbic system is known for reacting to internal and external chemical stimulants. 

Other structures in this area make up the limbic system which is directly linked to the olfactory system. Areas called the septal nuclei and amygdala contain regions often called the pleasure centres, with the hippocampus concerned with motivational memory. Projections from the cerebral cortex connect with the thalamus, hypothalamus and posterior pituitary gland. The network of connections between all these different areas of the brain is highly complex. The role of the limbic system is significant in autonomic (involuntary or non-conscious) reactions that are implicated with emotional responses including fear, rage and motivation. 

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