Intracerebroventricular Oxytocin Stimulates Maternal Behaviour in the Sheep

Abstract

The maternal behaviour of 7 ovariectomized, oestrogen-treated ewes was recorded after intracerebroventricular (ICV) infusions of oxytocin (OT). At weekly intervals 10-min behaviour tests were given starting 1 min after control (saline) or OT infusions. In the ewes’ home pens, 5-, 10- and 20-µg doses of OT significantly increased the frequency of some or all of the maternal behaviours scored (low-pitch bleats, sniffing, licking and approaching/following the lamb), and 3 ewes allowed suckling attempts. Aggressive (head butts) and negative (withdrawal from the lamb) behaviours significantly decreased in frequency. Vaginocervical stimulation (10 min duration) produced similar effects on these behaviours. When the lambs were removed from the ewes’ pens, the ewes exhibited significantly more high-pitch bleats (protest) following OT treatment. When 20 µg OT was given ICV in the absence of oestrogen priming, or when it was given intravenously with oestrogen priming, no significant effects on maternal behaviour were seen. Maternal behaviour was also significantly stimulated in oestrogen-treated ewes in a larger, novel testing environment (an enclosed area of field) following 5- and 20-µg doses of OT. In an additional experiment in the field enclosure it was found that ewes spent significantly more time near a lamb in a cage following both 5- and 20-µg doses of OT. In both experimental settings the high OT doses (10 and 20 µg) significantly increased the frequency of feeding although the effect was not dependent on oestrogen priming. These results demonstrate that central OT may play an important role in stimulating maternal behaviour in the sheep.

The neurobiology of social attachment: A comparative approach to behavioral, neuroanatomical, and neurochemical studies

“…Finally, OT and AVP were known to be important for the bond between mother and offspring. Indeed, central administration of OT has been found to enhance maternal behavior in sheep (Kendrick et al, 1987) and rats (Pederson et al, 1979).…”

“…This pairing of sex with peptide was probably chosen because of the known sexual dimorphism and testosterone sensitivity of the BNST-LS AVP pathway and involvement of OT in mother-infant bonding (Pederson et al, 1979;De Vries et al, 1983;Kendrick et al, 1987;De Vries et al, 1990;Kendrick et al, 1992). Thus, AVP and OT were thought to have gender specific effects; AVP regulating pair bonding in male prairie voles and OT regulating the same behavior in female prairie voles Williams et al, 1994;Insel et al, 1995a).…”

Stimulation of Maternal Behaviour in Rats with Cholecystokinin Octapeptide

“…However, as there is an immediate onset of the behaviour after parturition (l), factors in addition to ovarian hormones and prolactin are likely to contribute to the induction of maternal behaviour. Oxytocin is thought to be involved because this hormone stimulates maternal behaviour within hours if given to OB-treated rats and sheep (8)(9)(10). The present results suggest that CCK-8 may also play a role, since administration of this hormone via osmotic minipumps producing plasma concentrations of CCK-8 which approached those of lactating rats, rapidly stimulated maternal behaviour in OB-treated rats.…”

“…Thirdly, ip injection of CCK-8 activates magnocellular oxytocin-producing hypothalamic cells, leading to elevated plasma concentrations of oxytocin (7). Oxytocrn and oxytocin-producing neural pathways have been shown to bc involved in the control of maternal behaviour (8)(9)(10). Conseq uently, we investigated the possibility that CCK-8 may stimulate maternal behaviour.…”

Pathologic Evaluation of the Supraoptic and Paraventricular Nuclei in Dementia

“…In addition to its role in pregnancy, oxytocin is now recognized to be an important mediator of social cognition across species and gender, specifically increasing pro-social behaviours 12,20,21 . In animal models administration of oxytocin increases maternal behaviours including grooming, nesting, and pair bond formation [22][23][24] . In humans, administration of oxytocin to healthy adults increases trust and cooperative behaviours 25,26 , emotional empathy 27 , facial expression recognition [28][29][30] , and theory of mind skills 31 .…”