Maternal aggression in rodents: brain oxytocin and vasopressin mediate pup defence

Abstract

The most significant social behaviour of the lactating mother is maternal behaviour, which comprises maternal care and maternal aggression (MA). The latter is a protective behaviour of the mother serving to defend the offspring against a potentially dangerous intruder. The extent to which the mother shows aggressive behaviour depends on extrinsic and intrinsic factors, as we have learned from studies in laboratory rodents. Among the extrinsic factors are the pups' presence and age, as well as the intruders' sex and age. With respect to intrinsic factors, the mothers' innate anxiety and the prosocial brain neuropeptides oxytocin (OXT) and arginine vasopressin (AVP) play important roles. While OXT is well known as a maternal neuropeptide, AVP has only recently been described in this context. The increased activities of these neuropeptides in lactation are the result of remarkable brain adaptations peripartum and are a prerequisite for the mother to become maternal. Consequently, OXT and AVP are significantly involved in mediating the fine-tuned regulation of MA depending on the brain regions. Importantly, both neuropeptides are also modulators of anxiety, which determines the extent of MA. This review provides a detailed overview of the role of OXT and AVP in MA and the link to anxiety.

From sexual attraction to maternal aggression: When pheromones change their behavioural significance

“…A second interesting question is what causes females to change their behavioural response to male chemosignals, from attraction and mating facilitation to aggression after parturition (in fact a few days before, Mann et al, 1984;Bosch, 2013). In this respect, since olfactory cues (likely derived from pups) are critical for other aspects of maternal behaviour, we wondered whether intimate contact with pups providing full access to these olfactory cues might be a causal factor facilitating this change in behaviour.…”

“…However, female aggression starts a couple of days before parturition in both mice and rats (see Mann et al, 1984;Bosch et al, 2013), suggesting an additional role of endocrine factors acting during late pregnancy. Studies in rats indicate that pup-directed maternal behaviours are promoted by the action of prolactin onto a substrate of high oestradiol circulating levels after progesterone withdrawal (Bridges and Rosenheim, 1990).…”

“…Mann et al, 1984) and prolactin in murine maternal aggression are far from clear (Mann et al, 1980;Svare et al, 1982). Brain oxytocin is well known to play a pivotal role in the control of maternal aggression (see Bosch, 2013).…”

Madres, Madrinas y Vecinas. Neuroendocrinología del comportamiento maternal en el ratón.

“…Existe un vasto cuerpo de evidencia que relaciona estos neuropéptidos con toda clase de comportamientos sociales y afiliativos (Donaldson y Young, 2008). De hecho, en ratas se sabe que los circuitos cerebrales nonapeptidérgicos ejercen un papel clave en la agresión maternal (Bosch, 2013). La información sobre estos péptidos de la que se dispone actualmente en el ratón es escasa y fragmentaria, por lo que nos propusimos caracterizar su distribución y colocalizacion en el encéfalo de ratones hembra, empleando para ello una inmunofluorescencia doble.…”

“…La primera, como parte de la amígdala, está implicada en la gestión de conductas con elevada carga emocional, como pueden ser respuestas de miedo o ansiedad a estímulos amenazantes (LeDoux, Iwata, Cicchetti, y Reis, 1988). La oxitocina estaría inhibiendo este tipo de respuestas, haciendo a la madre capaz de afrontar la defensa de sus crías frente a amenazas importantes (Bosch, 2013;Knobloch y cols., 2012). La segunda, el núcleo accumbens, forma parte de los circuitos de la recompensa y sería responsable de atribuir un valor reforzante a las crías y, en consecuencia, motivar a la madre a su cuidado (Numan y Woodside, 2010).…”