The preoptic area is a region of the

hypothalamus The hypothalamus (: hypothalami; ) is a small part of the vertebrate brain that contains a number of nucleus (neuroanatomy), nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrin ...

MeSH Medical Subject Headings (MeSH) is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences. It serves as a thesaurus of index terms that facilitates searching. Created and updated by th ...

classifies it as part of the anterior hypothalamus. TA lists four nuclei in this region, (medial, median, lateral, and periventricular).

Functions

The preoptic area is responsible for

thermoregulation Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

and receives nervous stimulation from

thermoreceptors A thermoreceptor is a non-specialised sense receptor, or more accurately the receptive portion of a sensory neuron, that codes absolute and relative changes in temperature, primarily within the innocuous range. In the mammalian peripheral nervous ...

in the skin,

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

s, and hypothalamus itself.

Nuclei

Median preoptic nucleus

The

median preoptic nucleus The median preoptic nucleus is located dorsal to the other three nuclei of the preoptic area of the anterior hypothalamus. The hypothalamus is located just beneath the thalamus, the main relay station of the nervous system, and is considered p ...

is located along the midline in a position significantly dorsal to the other three preoptic nuclei, at least in the

crab-eating macaque The crab-eating macaque (''Macaca fascicularis''), also known as the long-tailed macaque or cynomolgus macaque, is a cercopithecine primate native to Southeast Asia. As a synanthropic species, the crab-eating macaque thrives near human settlem ...

brain. It wraps around the top (dorsal), front, and bottom (ventral) surfaces of the

anterior commissure The anterior commissure (also known as the precommissure) is a white matter nerve tract, tract (a bundle of axons) connecting the two temporal lobes of the cerebral hemispheres across the midline, and placed in front of the columns of the Fornix o ...

. The median preoptic nucleus generates

thirst Thirst is the craving for potable fluids, resulting in the basic instinct of animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmolites, suc ...

. Drinking decreases

noradrenaline Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as a hormone, neurotransmitter and neuromodulator. The name "noradrenaline" (from ...

release in the median preoptic nucleus.

Medial preoptic nucleus

The medial preoptic nucleus is bounded laterally by the lateral preoptic nucleus, and medially by the preoptic periventricular nucleus. It releases

gonadotropin-releasing hormone Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and rele ...

(GnRH), controls

copulation Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for sexual pleasure, reproduction, or both.Sexual inte ...

in males, and is larger in males than in females.

Parental behavior

The medial preoptic area (mPOA) has been implicated in parental care in both males and females. In rats,

oxytocin Oxytocin is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. Present in animals since early stages of evolution, in humans it plays roles in behavior that include Human bonding, ...

and

vasopressin Mammalian vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin, is a hormone synthesized from the ''AVP'' gene as a peptide prohormone in neurons in the hypothalamus, and is converted to AVP. It ...

are associated with maintaining maternal care through local release in the mPOA and the adjacent bed nucleus of the

stria terminalis The stria terminalis (or terminal stria) is a structure in the brain consisting of a band of fibers running along the lateral margin of the ventricular surface of the thalamus. Serving as a major output pathway of the amygdala, the stria termina ...

(BNST). Oxytocin and vasopressin V1a receptor binding are increased in both the mPOA and the BNST in lactating rats when compared to controls. The mPOA also has a high density of

estradiol Estradiol (E2), also called oestrogen, oestradiol, is an estrogen steroid hormone and the major female sex hormone. It is involved in the regulation of female reproductive cycles such as estrous and menstrual cycles. Estradiol is responsible ...

receptors that, when activated, can cause a male rat to show maternal-type behaviors. Additionally, the mPOA is critical for the onset and expression of parental behavior, as evidenced by increases in the immediate early gene

c-fos Protein c-Fos is a proto-oncogene that is the human homolog of the retroviral oncogene v-fos. It is encoded in humans by the ''FOS'' gene. It was first discovered in rat fibroblasts as the transforming gene of the FBJ MSV (Finkel–Biskis–Ji ...

, in experienced rat mothers or fathers when compared to controls. Also in fathers, studies have shown that when they receive ultrasonic or pheromone cues from their mates, their c-fos expression in the mPOA further increased, suggestive that rat paternal behavior is mediated through the mPOA but activated by direct interactions with a mate. Large lesions of the mPOA disrupt the onset of maternal behavior, nest-building, and pup retrieval, with the lateral projections being especially critical.

Sexual behavior

The mPOA is sexually dimorphic, that is, it differs in function between males and females. In females, studies have examined the influence of the mPOA on precopulatory and appetitive behaviors. Precopulatory behaviors involve several brain areas, including the mPOA as well as the medial

amygdala The amygdala (; : amygdalae or amygdalas; also '; Latin from Greek language, Greek, , ', 'almond', 'tonsil') is a paired nucleus (neuroanatomy), nuclear complex present in the Cerebral hemisphere, cerebral hemispheres of vertebrates. It is c ...

(MA) and BNST. Studies using female Syrian hamsters have shown that the mPOA is important for sexual odor preference. While control females will investigate male odors more than female odors, those with bilateral lesions to the mPOA (MPOA-X) will show no difference in odor preference, but vaginal scent marking and lordosis remained unaffected. Appetitive behaviors of female rats – including hops, darts, and solicitations – have been linked to

dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. It is an amine synthesized ...

(DA) transmission in the mPOA. Since

ascorbic acid Ascorbic acid is an organic compound with formula , originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves freely in water to give mildly acidic solutions. It is a mild reducing agent. Asco ...

(Vitamin C) enhances DA transmission in mesolimbic and nigrostriatal pathways, it has been shown that infusions of ascorbic acid into the mPOA increases appetitive behaviors compared to controls. In male rats, the mPOA affects the consummatory phase of sexual behavior, and possibly motivation, with lesions causing a complete loss of copulatory behaviors. Conversely, electrical stimulation of this area triggers male copulatory behavior, as measured by decreases in the latency to ejaculate. Furthermore,

testosterone Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...

implanted into the mPOA of castrated males completely restores mating, as long as

aromatase Aromatase (), also called estrogen synthetase or estrogen synthase, is an enzyme responsible for a key step in the biosynthesis of estrogens. It is CYP19A1, a member of the cytochrome P450 superfamily, which are monooxygenases that catalyze man ...

is not inhibited.

Ventrolateral preoptic nucleus

The

ventrolateral preoptic nucleus The ventrolateral preoptic nucleus (VLPO), also known as the intermediate nucleus of the preoptic area (IPA), is a small cluster of neurons situated in the anterior hypothalamus, sitting just above and to the side of the optic chiasm in the brai ...

, or intermediate nucleus, is adjacent to the medial preoptic nucleus. It also mediates non-REM sleep onset.

Preoptic periventricular nucleus

The preoptic periventricular nucleus is located along the midline and is medial to the medial preoptic nucleus.

References

{{Authority control Hypothalamus