Diversity of oxytocin neurones: Beyond magno‐ and parvocellular cell types?

In the rat supraoptic nucleus, every oxytocin cell projects to the posterior pituitary, and is involved both in reflex milk ejection during lactation and in regulating uterine contractions during parturition. All are also osmosensitive, regulating natriuresis. All are also regulated by signals that control appetite, including the neural and hormonal signals that arise from the gut after food intake and from the sites of energy storage. All are also involved in sexual behaviour, anxiety‐related behaviours and social behaviours. The challenge is to understand how a single population of neurones can coherently regulate such a diverse set of functions and adapt to changing physiological states. Their multiple functions arise from complex intrinsic properties that confer sensitivity to a wide range of internal and environmental signals. Many of these properties have a distant evolutionary origin in multifunctional, multisensory neurones of Urbilateria, the hypothesised common ancestor of vertebrates, insects and worms. Their properties allow different patterns of oxytocin release into the circulation from their axon terminals in the posterior pituitary into other brain areas from axonal projections, as well as independent release from their dendrites.

Section: Con Clus Ionsmentioning

confidence: 99%

The osmoresponsiveness of oxytocin and vasopressin neurones: Mechanisms, allostasis and evolution

Leng

Russell

2019

“…1,2 Hypothalamic parvocellular oxytocin-synthesising neurones project their axons to various brain regions, including the spinal cord, dorsal vagal complex, nucleus tractus solitarius, rostral ventral medulla, ventral tegmental area and hypothalamus. 1,2 Hypothalamic parvocellular oxytocin-synthesising neurones project their axons to various brain regions, including the spinal cord, dorsal vagal complex, nucleus tractus solitarius, rostral ventral medulla, ventral tegmental area and hypothalamus.…”

Section: Introductionmentioning

confidence: 99%

Role of oxytocin in the control of stress and food intake

Onaka

Takayanagi

2019

Oxytocin neurones in the hypothalamus are activated by stressful stimuli and food intake. The oxytocin receptor is located in various brain regions, including the sensory information‐processing cerebral cortex; the cognitive information‐processing prefrontal cortex; reward‐related regions such as the ventral tegmental areas, nucleus accumbens and raphe nucleus; stress‐related areas such as the amygdala, hippocampus, ventrolateral part of the ventromedial hypothalamus and ventrolateral periaqueductal gray; homeostasis‐controlling hypothalamus; and the dorsal motor complex controlling intestinal functions. Oxytocin affects behavioural and neuroendocrine stress responses and terminates food intake by acting on the metabolic or nutritional homeostasis system, modulating emotional processing, reducing reward values of food intake, and facilitating sensory and cognitive processing via multiple brain regions. Oxytocin also plays a role in interactive actions between stress and food intake and contributes to adaptive active coping behaviours.

“…Magnocellular neurones in the SON project to the pituitary to release OXT into the bloodstream, although they can also release OXT into the cerebrospinal fluid. 30 The release of OXT from magnocellular OXT neurones in the SON appears to be regulated by parvocellular OXT neurones in the PVN. 31 If there is a decrease in OXT production from P14 to P90 in the PVN, this could impair the modu- (1,6) .115…”

Section: Discussionmentioning

confidence: 99%

“…Interestingly we observed an increase in Oxt mRNA levels in the SON in OXTR KO mice compared to WT at P90 in both sexes. Magnocellular neurones in the SON project to the pituitary to release OXT into the bloodstream, although they can also release OXT into the cerebrospinal fluid . The release of OXT from magnocellular OXT neurones in the SON appears to be regulated by parvocellular OXT neurones in the PVN .…”

Section: Discussionmentioning

confidence: 99%

Oxytocin receptor gene loss influences expression of the oxytocin gene in C57BL/6J mice in a sex‐ and age‐dependent manner

Vaidyanathan

Hammock

2020

Parental care and sensory stimulation are critical environmental factors that influence oxytocin (OXT) and its receptor (OXTR). Because developmental Oxt mRNA expression is enhanced by sensory‐rich early life experience and reduced by sensory deprivation, we predicted that compared to wild‐type (WT) littermates, mice with congenital loss of OXTR (OXTR KO), as a genetically induced deprivation, would show impaired Oxt mRNA expression in the offspring hypothalamus during development. Oxt mRNA levels of male and female OXTR KO mice were not different from WT littermates from postnatal day (P)0 to P6, although, by P8, OXTR KO showed significantly decreased Oxt mRNA expression in the hypothalamus compared to WT littermates. At P14, male and female OXTR KO mice had significantly decreased Oxt mRNA expression specifically in the paraventricular nucleus (PVN), but not the supraoptic nucleus (SON), compared to WT littermates. We investigated whether this effect persisted in adulthood (P90) and found a significant genotype by sex interaction where male OXTR KO mice displayed a reduction in Oxt expression specific to the PVN compared to male WT littermates. By contrast, male and female OXTR KO adults had increased Oxt mRNA levels in the SON. These findings suggest that OXTR plays a role in developmental Oxt mRNA expression with sex by genotype interactions apparent at adulthood. We then measured OXT and neural activation in the PVN and SON at P14. We observed more OXT‐immunoreactive cells in the PVN of OXTR KO mice but significantly fewer c‐Fos immunoreactive cells. There were no genotype differences in immunoreactivity for OXT and no c‐Fos activity in the SON at P14. Combined, these data suggest that OXTR WT P14 mice have more PVN activity and are more likely to release OXT than OXTR KO mice. Future experiments are warranted to understand which OXTR‐expressing neural circuits modulate the development of the PVN oxytocin system.