Sunday, February 11, 2007
Inhalable oxytocin could become a cure for social fears
Oxytocin is a hormone long known for its effects in the human body. It helps spur labour contractions, breastfeeding and orgasm. It has also long figured in research on bonding in animals.
Researchers now report they can boost oxytocin in the human brain using a nasal spray. And when they do, trust seems to rise and social fear seems to abate, raising the possibility that oxytocin-based drugs might eventually help people with mental illnesses that involve fear of others, from crippling shyness to autism and schizophrenia.
This month, Meyer-Lindenberg and others reported in The Journal of Neuroscience that when young men snorted oxytocin, brain scans showed that fear centres became less responsive to threatening faces.
The journal Nature recently published research showing that when subjects played a game that hinged on trust, those who had snorted oxytocin were more likely to trust other players.
Also, brain scans suggest that the fear centres in the brains of autistic people are hypersensitive in social situations, so perhaps oxytocin could help quiet them.
Oxytocin research has been reaching the kind of critical mass that all but guarantees that pharmaceutical companies will be seeking to develop oxytocin-based drugs, said Robert Ring, a neuroscientist and oxytocin researcher at Wyeth Pharmaceuticals.
Ring reported at last month's Society for Neuroscience conference that oxytocin or a similar molecule reduced anxiety in mice subjected to a variety of stressful situations.
"These results suggest that the development of oxytocin-like drugs may offer a novel way to treat anxiety disorders in humans," he said.
But the new work on oxytocin is spurring other warnings. Some researchers note that it may have potential as a date-rape drug, since oxytocin is involved both in trust and in sexual arousal.
7:35 PM
let our love blossom this valentine..
Saturday, February 10, 2007
Oxytocin in Autism
Autism is one of the most widely diagnosed developmental disabilities in the nation. The number of children diagnosed with autism has increased 10 times in the last 20 years. Boys with autism outnumber girls four to one. Oxytocin is known to be important to social behavior and social interest – areas that are difficult for children with autism. Oxytocin levels have previously been found to be low in boys with autism, but have not been studied in autistic girls.
Oxytocin dysfunction might contribute to the development of social deficits in autism, a core symptom domain and potential target for intervention. This study explored the effect of intravenous oxytocin administration on the retention of social information in autism.
METHODS: Oxytocin and placebo challenges were administered to 15 adult subjects diagnosed with autism or Asperger's disorder, and comprehension of affective speech (happy, indifferent, angry, and sad) in neutral content sentences was tested.
RESULTS: All subjects showed improvements in affective speech comprehension from pre- to post-infusion; however, whereas those who received placebo first tended to revert to baseline after a delay, those who received oxytocin first retained the ability to accurately assign emotional significance to speech intonation on the speech comprehension task.
CONCLUSIONS: These results are consistent with studies linking oxytocin to social recognition in rodents as well as studies linking oxytocin to prosocial behavior in humans and suggest that oxytocin might facilitate social information processing in those with autism. These findings also provide preliminary support for the use of oxytocin in the treatment of autism.
6:55 PM
let our love blossom this valentine..
Friday, February 9, 2007
Hormone that Builds Trust
In this study, published in the Proceedings of the National Academy of Sciences, researchers showed the hormone's receptor may also facilitate the formation of trust demonstrated through social bonding. A hormone uses a receptor to bind to a cell and perform its duties.
The results showed that male and female mice that lacked the oxytocin receptor had problems forming trust and establishing normal social relationships.
For example, female mice lacking the oxytocin receptor had impaired nurturing abilities and were slow to retrieve their pups when they wandered off.
Male mice lacking the receptor tended to be more aggressive toward other males and had "social amnesia" when separated and reintroduced to a female. The males also had less vocalized calls and a greater tendency to move around and explore.
Researchers say other hormones may sometimes compensate for a lack of oxytocin, but this hormone appears to play a key role in social bonding and the formation of trust.
6:37 PM
let our love blossom this valentine..
Thursday, February 8, 2007
Effects of Oxytocin on Males
Males synthesize oxytocin in the same regions of the hypothalamus as in females, and also within the testes and perhaps other reproductive tissues. Pulses of oxytocin can be detected during ejaculation. Current evidence suggests that oxytocin is involved in facilitating sperm transport within the male reproductive system, due to its presence in seminal fluid. It may also have effects on some aspects of male sexual behavior.
8:09 PM
let our love blossom this valentine..
Wednesday, February 7, 2007
Effects of Oxytocin on Females
In years past, oxytocin had the reputation of being an "uncomplicated" hormone, with only a few well-defined activities related to birth and lactation. As has been the case with so many hormones, further research has demonstrated many subtle but profound influences of this little peptide. Nevertheless, it has been best studied in females where it clearly mediates three major effects:
Stimulation of milk ejection (milk letdown): Milk is initially secreted into small sacs within 
the mammary gland called alveoli, from which it must be ejected for consumption or harvesting. Mammary alveoli are surrounded by smooth muscle (myoepithelial) cells which are a prominant target cell for oxytocin. Oxytocin stimulates contraction of myoepithelial cells, causing milk to be ejected into the ducts and cisterns.
Stimulation of uterine smooth muscle contraction at birth: At the end of gestation, the uterus must contract vigorously and for a prolonged period of time in order to deliver the fetus. During the later stages of gestation, there is an increase in abundance of oxytocin receptors on uterine smooth muscle cells, which is associated with increased "irritability" of the uterus (and sometimes the mother as well). Oxytocin is released during labor when the fetus stimulates the cervix and vagina, and it enhances contraction of uterine smooth muscle to facilitate parturition or birth.
In cases where uterine contractions are not sufficient to complete delivery, physicians and veterinarians sometimes administer oxytocin ("pitocin") to further stimulate uterine contractions - great care must be exercised in such situations to assure that the fetus can indeed be delivered and to avoid rupture of the uterus.
Establishment of maternal behavior: Successful reproduction in mammals demands that mothers become attached to and nourish their offspring immediately after birth. It is also important that non-lactating females do not manifest such nurturing behavior. The same events that affect the uterus and mammary gland at the time of birth also affect the brain. During parturition, there is an increase in concentration of oxytocin in cerebrospinal fluid, and oxytocin act
ing within the brain plays a major role in establishing maternal behavior.Evidence for this role of oxytocin come from two types of experiments. First, infusion of oxytocin into the ventricles of the brain of virgin rats or non-pregnant sheep rapidly induces maternal behavior. Second, administration into the brain of antibodies that neutralize oxytocin or of oxytocin antagonists will prevent mother rats from accepting their pups. Other studies support the contention that this behavioral effect of oxytocin is broadly applicable among mammals.
While all of the effects described above, doubt has recently been cast on its necessity in parturition and maternal behavior. Mice that are unable to secrete oxytocin due to targeted disruptions of the oxytocin gene will mate, deliver their pups without apparent difficulty and display normal maternal behavior. However, they do show deficits in milk ejection and have subtle derangements in social behavior. It may be best to view oxytocin as a major facilitator of parturition and maternal behavior rather than a necessary component of these processes.
6:13 PM
let our love blossom this valentine..
Tuesday, February 6, 2007
Effects of Oxytocin in general
- Sexual arousal. Oxytocin injected into the cerebrospinal fluid causes spontaneous erections in rats, reflecting actions in the hypothalamus and spinal cord.
- Bonding. In the Prairie Vole, oxytocin released into the brain of the female during sexual activity is important for forming a monogamous pair bond with her sexual partner. Vasopressin appears to have a similar effect in males. In people, plasma concentrations of oxytocin have been reported to be higher amongst people who claim to be falling in love. Oxytocin has a role in social behaviors in many species, and so it seems likely that it has similar roles in humans. It has been suggested that deficiencies in oxytocin pathways in the brain might be a feature of autism.
- Maternal behavior. Sheep and rat females given oxytocin antagonists after giving birth do not exhibit typical maternal behavior. By contrast, virgin sheep females show maternal behavior towards foreign lambs upon cerebrospinal fluid infusion of oxytocin, which they would not do otherwise.
- Various anti-stress functions. Oxytocin reduces blood pressure and cortisol levels, increasing tolerance to pain, and reducing anxiety. Oxytocin may play a role in encouraging "tend and befriend", as opposed to "fight or flight", behavior, in response to stress.
- Increasing trust and reducing fear. In a risky investment game, experimental subjects given nasally administered oxytocin displayed "the highest level of trust" twice as often as the control group. Subjects who were told that they were interacting with a computer showed no such reaction, leading to the conclusion that oxytocin was not merely affecting risk-aversion. Nasally-administered oxytocin has also been reported to reduce fear, possibly by inhibiting the amygdala (which is thought to be responsible for fear responses). There is no conclusive evidence for access of oxytocin to the brain through intranasal administration, however.
- According to some studies in animals, oxytocin inhibits the development of tolerance to various addictive drugs (opiates, cocaine, alcohol) and reduces withdrawal symptoms.
- Preparing fetal neurons to delivery. Crossing placenta, maternal oxytocin reaches fetal brain and induces a switch in the action of neurotransmitter GABA from excitatory to inhibitory on fetal cortical neurons. This silences fetal brain for the period of delivery and reduces its vulnerability to hypoxic damage.
- Certain learning and memory functions are impaired by centrally-administered oxytocin.
4:00 PM
let our love blossom this valentine..
Monday, February 5, 2007
Control of Oxytocin SecretionThe most important stimulus for release of hypothalamic oxytocin is initiated by physical stimulation of the nipples or teats. The act of nursing or suckling is relayed within a few milliseconds to the brain via a spinal reflex arc. These signals impinge on oxytocin-secreting neurons, leading to release of oxytocin.
If you want to obtain anything other than trivial amounts of milk from animals like dairy cattle, you have to stimulate oxytocin release because something like 80% of the milk is available only after ejection, and milk ejection requires oxytocin. Watch someone milk a cow, even with a machine, and what you'll see is that prior to milking, the teats and lower udder are washed gently - this tactile stimulation leads to oxytocin release and milk ejection.
A number of factors can inhibit oxytocin release, among them acute stress. For example, oxytocin neurons are repressed by catecholamines, which are released from the adrenal gland in response to many types of stress, including fright. As a practical endocrine tip - don't wear a gorilla costume into a milking parlor full of cows or set off firecrackers around a mother nursing her baby.
Both the production of oxytocin and response to oxytocin are modulated by circulating levels of sex steroids. The burst of oxytocin released at birth seems to be triggered in part by cervical and vaginal stimulation by the fetus, but also because of abruptly declining concentrations of progesterone. Another well-studied effect of steroid hormones is the marked increase in synthesis of uterine (myometrial) oxytocin receptors late in gestation, resulting from increasing concentrations of circulating estrogen.
7:00 PM
let our love blossom this valentine..
Sunday, February 4, 2007
Where is Oxytocin found??
Oxytocin secreted from the pituitary gland cannot re-enter the brain because of the blood-brain barrier. Instead, the behavioral effects of oxytocin are thought to reflect release from centrally-projecting oxytocin neurons, different from those that project to the pituitary gland. Oxytocin receptors are expressed by neurons in many parts of the brain and spinal cord, including the amygdala, ventromedial hypothalamus, septum and brainstem.
9:18 PM
let our love blossom this valentine..
Saturday, February 3, 2007
What is Oxytocin??
Oxytocin (Greek: "quick birth") is a mammalian hormone that also acts as a neurotransmitter in the brain. In women, it is released mainly after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating birth and breastfeeding, respectively. Oxytocin is released during orgasm in both sexes. In the brain, oxytocin is involved in social recognition and bonding, and might be involved in the formation of trust between people.
6:25 PM
let our love blossom this valentine..
Friday, February 2, 2007
Introduction
We have puzzled over the mystery of to whom we are attracted, we often said "It's chemistry". It should come as no suprpise that indeed chemistry plays a big role. Internally, we are driven by hormone called oxytocin. This hormone determines how our bodies respond to love and affection. Oxytocin makes us feel good when we are close to loved ones, including pets.
How often do you hug and hold each other’s hands? Recent research shows it’s good for your health. Between loving partners, parents and children, or even close friends, physical affection can help the brain, the heart and other body systems you might never have imagined.
5:08 AM
let our love blossom this valentine..
