Oxytocin and Behavior

The milk-ejection reflex of the rat is closely associated with synchronized activity of the cortical electroencephalogram (EEG), and the frequency of milk ejections has been shown to be greatly facilitated by central oxytocin. The following experiments were undertaken to examine the changes in the EEG during facilitation of the reflex by central oxytocin. lntracerebroventricular injection of 1 mU (2.2 ng) oxytocin during suckling caused a rapid increase in the frequency of milk ejections but no change in the predominantly synchronized pattern of the EEG. However, after a delay (11.3+0.8 min, meankSE) there appeared to be an increasing proportion of desynchronization, which correlated with cessation of the facilitated milk-ejection responses. Hence, the observed EEG desynchronization may signal activation of mechanisms inhibitory to the milk-ejection reflex.In the absence of the suckling stimulus oxytocin also caused a change to desynchronization. However, this effect was more pronounced and commenced after a much shorter latency (1.7k0.4 min, mean kSE; P

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“…The profound desynchronizing effect of oxytocin reported here supports its involvement in modulating behavioural arousal (20).…”

Section: -supporting

confidence: 75%

Effect of Centrally Administered Oxytocin on the Association Between Cortical Electroencephalogram and Milk Ejection in the Rat

Wakerley

Foreman

Ingram

1989

J Neuroendocrinology

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“…Whereas central OXT seems not to play a significant role in established maternal behaviour of lactating rats (15) it may be involved more generally in behavioural regulation, e.g. in the management of adaptation to environmental challenges in the postpartum period (17,39). In this context it is of interest to note that the septo-hippocampal system plays an essential role in the so-called behavioural inhibition which is characterized by the maintenance of a high level of arousal, high alertness and anxious anticipation (20,21).…”

Section: Discussionmentioning

confidence: 99%

“…Evidence for such release would provide strong support for the idea that OXT may be physiologically involved in central processes related to lactation. Two of the brain areas thought to be involved in milk ejection (18,19) as well as in behavioural regulation (17,20,21) are the septum and dorsal hippocampus. Therefore, in the present study, we investigated the release of endogenous OXT and AVP within both limbic brain areas in the lactating, freely-behaving rat, and the effects of suckling.…”

mentioning

confidence: 99%

Septal and Hippocampal Release of Oxytocin, but not Vasopressin, in the Conscious Lactating Rat During Suckling

Neumann

Landgraf

1989

J Neuroendocrinology

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The central release of both oxytocin and vasopressin within the septum and dorsal hippocampus in response to suckling was studied in conscious, freely-behaving lactating rats. Three consecutive 30-min push-pull perfusions were carried out before, during and after suckling (suckled group) or without suckling (control group). As compared to control levels, suckling resulted in a significantly increased oxytocin release within both limbic brain areas (septum: to 140%, dorsal hippocampus: to 1,600%). After removal of the suckling pups, the oxytocin concentration in the final perfusates remained at the stimulation level (septum) or tended to return to control values (dorsal hippocampus). In contrast to oxytocin, the vasopressin perfusate levels did not differ significantly between unsuckled and suckled ratsThe stimulation of magnocellular oxytocinergic neurons of the hypothalamus during suckling results in a pulsatile and periodic release of oxytocin (OXT) from the posterior pituitary (1, 2). At the mammary gland, the peptide promotes the contraction of myoepithelial cells which surround the alveoli, making milk available for the suckling pups. Each OXT release is the result of high frequency bursts of spikes which occur simultaneously in most or all magnocellular OXT cells in the paraventricular and supraoptic nuclei (3-5). In contrast to OXT, arginine vasopressin (AVP) seems not to be involved in this process (6)(7)(8).In addition to the hypothalamo-neurohypophysial projection, immunocytochemical techniques have located OXT-and AVPcontaining fibre terminals in a number of extrahypothalamic brain areas, including the septum and the dorsal hippocampus (9, 10). From these terminals, both OXT and AVP are released in response to appropriate stimulation (1 1 -13). There is considerable evidence suggesting central effects not only of AVP (14), but also of OXT, including its possible role in influencing behavioural phenomena in the post partum period (15-17). However, little is known whether the peripheral release of OXT, e.g. in response to suckling, is accompanied by central release. Evidence for such release would provide strong support for the idea that OXT may be physiologically involved in central processes related to lactation. Two of the brain areas thought to be involved in milk ejection (18,19) as well as in behavioural regulation (17,20,21) are the septum and dorsal hippocampus. Therefore, in the present study, we investigated the release of endogenous OXT and AVP within both limbic brain areas in the lactating, freely-behaving rat, and the effects of suckling. Res u I tsIn the perfusates sampled from control animals and in the prestimulation perfusates, respectively, both peptides were detectable (septum: OXT 2.50 to 4.60pg/sample, AVP 0.30 to 4.80 pg/sample; dorsal hippocampus: OXT 0.30 to 10.5 pg/ sample, AVP 0.30 to 10.3 pg/sample).Compared to unsuckled controls, in suckled rats there was a significantly increased OXT concentration in perfusates from both the septum (to approximately 140%; P

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“…The stimulatory influence of PRL on OT secretion may also explain the increased, possibly OT-mediated, maternal behavior during pregnancy and lactation. 71,72 …”

Section: Oxytocin Release During Hyperprolactinemiamentioning

confidence: 99%

Pituitary Portal Plasma Levels of Oxytocin during the Estrous Cycle, Lactation, and Hyperprolactinemia

Sarkar

Frautschy

Mitsugi

1992

Annals of the New York Academy of Sciences

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Oxytocin and Behavior

Cited by 23 publications

References 147 publications

Effect of Centrally Administered Oxytocin on the Association Between Cortical Electroencephalogram and Milk Ejection in the Rat

Effect of Centrally Administered Oxytocin on the Association Between Cortical Electroencephalogram and Milk Ejection in the Rat

Septal and Hippocampal Release of Oxytocin, but not Vasopressin, in the Conscious Lactating Rat During Suckling

Pituitary Portal Plasma Levels of Oxytocin during the Estrous Cycle, Lactation, and Hyperprolactinemia

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