Child loss induces short- and long-term neurobiological changes

An animal model for child loss suggests that this important (negative) life event is associated with changes in neurobiology, which could explain behavioural changes observed in bereaved parents.

It has been known for some time that positive social relationships are associated with positive physical and mental health. A very important social relationship is the bond between a parent and child, so it is no surprise that the impact of infant loss ranks among the most stressful life events. Over 90% of bereaved parents develop prolonged grief disorder (PGD) [1]. Currently, there is no specific treatment for PGD, mostly because of a lack of knowledge on the neurobiology of grief. Prof. Oliver Bosch (University of Regensburg, Germany) explored the neurobiological effects of child loss in a rat model [2].

In the rat model, early separation (after 1–6 days) of mother and pup induced an increased activation of layer II and III of the prelimbic cortex and of the basolateral amygdala, compared with the brains of control mothers. In addition, separation induced a positive correlation between the activation of these 2 brain areas; in control mothers this correlation was absent. Corresponding data was found recently in humans [3].

Prof. Bosch further explained that there is a balance between pro- and anti-maternal peptides in the maternal brain. Oxytocin, vasopressin, and prolactin act ‘pro-maternal’ and are up-regulated after giving birth, while corticotropin-releasing factor acts ‘anti-maternal’ and is down-regulated after giving birth [4]. The rat model showed that short-term separation was associated with a decrease in oxytocin receptors in the central amygdala, whereas long-term separation was associated with recovery of oxytocin receptors in the central amygdala and with upregulation of oxytocin receptors in the prelimbic cortex. The latter could be a compensatory mechanism for the decrease in oxytocin concentration in the brain after separation, Prof. Bosch suggested.

Behavioural tasks demonstrated no effect of short-term separation, while long-term separation induced less anxious behaviour. This is opposite to what has been observed in humans [5]. In addition, long-term separation was associated with increased passive stress-coping, which is in line with the high percentage of PGD in bereaved parents.

How the separation of mother and pup influences the corticotropin-releasing factor system is still under investigation. However, other animal experiments with partner separation indicate that this life event upregulates brain corticotropin-releasing factor system activation, eventually leading to impaired oxytocin signalling and negative effects on well-being.

“Our studies on lactating rats present a first approach to advance our understanding of how permanent separation from the offspring can cause a dysregulation of the brain oxytocin and corticotropin-releasing factor systems, thereby leading to severe emotional and behavioural consequences,” concluded Prof. Bosch.

1. McCarthy MC, et al. J Palliat Med. 2010;13:1321–1326.
2. Bosch O, et al. The devastating effect of child loss on the mother – targeting brain CRF and OXT in grief and bereavement. Abstract S11.02, ECNP Congress 2022, Vienna, Austria, 15–18 October.
3. Kark SM, et al. Front Hum Neurosci. 2022;16:925242.
4. Demarchi L, et al. Peptides. 2021;143:170593.
5. Pohl TT, et al. Int J Psychophysiology. 2019;136:54–63.

 

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Posted on 28 November, 202228 November, 2022