Prolactin system in the hippocampus

Abstract

Among the more than 300 biological actions described for prolactin, its role in the neurogenic capacity of the hippocampus, which increases synaptogenesis and neuronal plasticity, consolidates memory and acts as a neuronal protector against excitotoxicity-effects mediated through its receptors are more recently known. The detection of prolactin in the hippocampus and its receptors, specifically in the Ammon's horn and dentate gyrus, opened up a new field of study on the possible neuroprotective effect of hormones in a structure involved in learning and memory, as well as in emotional and behavioral processes. It is currently known, although controversial, that prolactin may be related to sex and age and that the hormone could be synthesized in the hippocampus itself. However, the regulatory mechanisms of changes in prolactin or in its hippocampal receptors still remain unknown. This review introduces the reader to general aspects concerning prolactin and its receptors and to what is currently known about the role prolactin plays in the brain and, in particular, in the hippocampus.

Coordinated transcriptional regulation by thyroid hormone and glucocorticoid interaction in adult mouse hippocampus-derived neuronal cells

“…Thyroid hormone and GC synergy in regulating growth hormone receptor expression in rodent pituitary cells has actually been reported as early as the 1970s [120] and is one of the well-established processes regulated by both hormone axes [121, 122]. While our results are consistent with the known effect of TH and GC in the hypothalamus and pituitary cells which then consequently affects the timing of development and regulation of body size, prolactin also has specific functions in neurodevelopment and neuroprotection in the hippocampus [123, 124]. For example, prolactin administration exerts a neuroprotective effect on hippocampal neurons in both in vivo and in vitro rodent models of excitotoxicity [125, 126].…”

Pregnancies alters spine number in cortical and subcortical limbic brain regions of old rats

“…Another hormone that raises its levels in the post‐pregnancy stage is prolactin, whose receptors are located in the PFC and the hippocampus, among others (Bakowska & Morrell, ; Cabrera‐Reyes, Vergara‐Castañeda, Rivero‐Segura, & Cerbón, ). Recent studies have also suggested that this hormone may improve cognition and play a neuroprotective role, showing an increase in the density of dendritic spines in the PFC and CA1 of the hippocampus during lactation (Carretero et al, ; Chen et al, ; Salmaso, Quinlan, Brake, & Woodside, ). However, to know if this hormone participates in the changes described in the present work, it is necessary to study only the effect of pregnancy without lactation to resolve this question.…”

Polygenic risk for circulating reproductive hormone levels and their influence on hippocampal volume and depression susceptibility

“…Like progesterone, the link between plasma prolactin and the hippocampus has not been properly investigated in humans. While there is a large body of work suggesting that prolactin can impact the rodent hippocampus at the cellular level (Cabrera-Reyes et al, 2017; Carretero et al, 2018; Morales et al, 2014), this does not appear to translate to any change in whole hippocampal volume (Torner et al, 2009). There is evidence from animal and cellular models that reproductive hormones can influence the hippocampus at the cellular level through changes in AHN, cell survival or branching (Chan et al, 2014; Morales et al, 2014; Ransome and Boon, 2015), therefore it is possible that this may also occur in humans without affecting whole hippocampal volume.…”