From: david gobel (davegobel@erols.com)
Date: Sun Apr 18 1999 - 16:49:20 MDT
Psychoneuroendocrinology 1998 Nov;23(8):819-35
Oxytocin may mediate the benefits of positive social interaction and
emotions.
Uvnas-Moberg K
Department of Physiology and Pharmacology, Karolinska Institute, Stockholm,
Sweden. kerstin.uvnas-moberg@fyka.ki.se
[Medline record in process]
During breastfeeding or suckling, maternal oxytocin levels are raised by
somatosensory stimulation. Oxytocin may, however, also be released by
nonnoxious stimuli such as touch, warm temperature etc. in plasma and in
cerebrospinal fluid. Consequently, oxytocin may be involved in physiological
and behavioral effects induced by social interaction in a more general
context. In both male and female rats oxytocin exerts potent physiological
antistress effects. If daily oxytocin injections are repeated over a 5-day
period, blood pressure is decreased by 10-20 mmHg, the withdrawal latency to
heat stimuli is prolonged, cortisol levels are decreased and insulin and
cholecystokinin levels are increased. These effects last from 1 to several
weeks after the last injection. After repeated oxytocin treatment weight
gain may be promoted and the healing rate of wounds increased. Most
behavioral and physiological effects induced by oxytocin can be blocked by
oxytocin antagonists. In contrast, the antistress effects can not,
suggesting that unidentified oxytocin receptors may exist. The prolonged
latency in the tail-flick test can be temporarily reversed by administration
of naloxone, suggesting that endogenous opioid activity has been increased
by the oxytocin injections. In contrast, the long-term lowering of blood
pressure and of cortisol levels as well as the sedative effects of oxytocin
have been found to be related to an increased activity of central alpha
2-adrenoceptors. Positive social interactions have been related to
health-promoting effects. Oxytocin released in response to social stimuli
may be part of a neuroendocrine substrate which underlies the benefits of
positive social experiences. Such processes may in addition explain the
health-promoting effects of certain alternative therapies. Because of the
special properties of oxytocin, including the fact that it can become
conditioned to psychological state or imagery, oxytocin may also mediate the
benefits attributed to therapies such as hypnosis or meditation.
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