Electrophysiological Evidence for a Key Control Function of the Medial Preoptic Area in the Regulation of Prolactin Secretion in Cycling, Pregnant and Lactating Rats

Wiersma, J.; Kastelijn, J.

doi:10.1159/000125332

Cited by 16 publications

(9 citation statements)

References 14 publications

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“…Although the POA neurones appear to be involved in the regulation of prolactin secretion, the mechanism involved in this control remains unclear. Even though lesion of the POA blocks the prolactin surge induced by oestradiol in ovariectomised rats (52), its electrical stimulation reduces prolactin release in cycling rats during the afternoons of pro‐oestrous and oestrous (53). In dopaminergic neurones of the VMPO, an increase in ERα expression was also observed on the afternoon of oestrous.…”

Section: Discussionmentioning

confidence: 99%

Alpha‐Oestrogen and Progestin Receptor Expression in the Hypothalamus and Preoptic Area Dopaminergic Neurones During Oestrous in Cycling Rats

Leite¹,

Szawka²,

Anselmo-Franci³

2007

J Neuroendocrinology

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A secretory surge of prolactin occurs on the afternoon of oestrous in cycling rats. Although prolactin is regulated by ovarian steroids, plasma oestradiol and progesterone levels do not vary during oestrous. Because prolactin release is tonically inhibited by hypothalamic dopamine and modulated by dopamine transmission in the preoptic area (POA), the present study aimed to evaluate whether oestrogen receptor (ER)-alpha and progestin receptor (PR) expression in the dopaminergic neurones of arcuate (ARC), periventricular, anteroventral periventricular (AVPe) and ventromedial preoptic (VMPO) nuclei changes during the day of oestrous. Cycling rats were perfused every 2 h from 10-20 h on oestrous. Brain sections were double-labelled to ERalpha or PR and tyrosine hydroxylase (TH). The number of TH-immunoreactive (ir) neurones did not vary significantly in any area evaluated. ERalpha expression in TH-ir neurones increased at 14 and 16 h in the rostral-ARC and dorsomedial-ARC, 14 h in the caudal-ARC and 16 h in the VMPO, whereas it was unaltered in the ventrolateral-ARC, periventricular and AVPe. PR expression in TH-ir neurones of the periventricular and rostral, dorsomedial, ventrolateral and caudal-ARC decreased transitorily during the afternoon, showing the lowest levels between 14 and 16 h; but it did not vary in the AVPe and VMPO. Plasma oestradiol and progesterone concentrations were low and unaltered during oestrous, indicating that the changes in receptors expression were probably not due to variation in ligand levels. Thus, our data suggest that variations in ERalpha and PR expression may promote changes in the activity of medial basal hypothalamus and POA dopaminergic neurones, even under unaltered secretion of ovarian steroids, which could facilitate the occurrence and modulate the magnitude of the prolactin surge on oestrous.

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Section: Discussionmentioning

confidence: 99%

Alpha‐Oestrogen and Progestin Receptor Expression in the Hypothalamus and Preoptic Area Dopaminergic Neurones During Oestrous in Cycling Rats

Leite¹,

Szawka²,

Anselmo-Franci³

2007

J Neuroendocrinology

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“…We have already reviewed the neural pathways over which olfactory input can reach the POA. The POA may also receive suckling-related sensory inputs because the MPOA influences prolactin release during lactation (37) and because the POA receives neural inputs from the peripeduncular nucleus of the midbrain (38). This midbrain region relays somatic-sensory suckling inputs related to lactational physiology (39).…”

Section: Medial Preoptic Area Output Circuits and Maternal Behaviormentioning

confidence: 99%

A neural circuitry analysis of maternal behavior in the rat

Numan

1994

Acta Paediatrica

109

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Numan M. A neural circuitry analysis of maternal behavior in the rat. Acta Pzdiatr 1994; This article reviews work that shows that the medial preoptic area of the hypothalamus plays a crucial role in controlling the occurrence of maternal behavior in rats. A primary goal of this report is to fit the medial preoptic area into a larger neural circuitry, examining its critical inputs and outputs. Lesions of the medial preoptic area disrupt maternal behavior and estradiol and prolactin injections into this region activate maternal behavior. The medial amygdala, which is located in the limbic telencephalon, sends a neural projection to the preoptic region. Research indicates that this projection influences maternal behavior by relaying olfactory input to the medial preoptic area. The output of the preoptic area influences maternal behavior through descending projections to the brain stem. One of the influences of such projections might be to regulate neural circuits involved in controlling specific maternal responses, such as retrieval (carrying of pups) behavior. Amygdala, brain stem, maternal behavior, medial preoptic area, rats

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“…Retrochiasmatic cuts that separated the preoptic area (POA) and/or the suprachiasmatic nucleus (SCN) from the arcuate nucleus-median eminence, or direct lesion in the SCN, eliminated both surges of PRL [18, 19, 20], suggesting the POA and the SCN might be important for PRL rhythmicity. Electrical lesions or stimulation in the medial preoptic area revealed that this area might regulate the surges of PRL secretion [21, 22, 23], suggesting a dual function of neuronal systems in this hypothalamic area. It may possess one neuronal system that inhibits nocturnal surges, and another neuronal system that can activate diurnal surges [21, 22].…”

Section: Introductionmentioning

confidence: 99%

Semicircadian Rhythms of c-Fos Expression in Several Hypothalamic Areas during Pregnancy in the Rat: Relationship to Prolactin Secretion

Lee

Arbogast²,

Voogt³

1998

Neuroendocrinology

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Prolactin (PRL) serves an important luteotrophic function in the rat during early pregnancy, expressed as a nocturnal surge in the early morning and a diurnal surge in the late afternoon. Several areas of the hypothalamus, including the preoptic area (POA), the suprachiasmatic nucleus (SCN) and the ventromedial and dorsomedial nuclei (VM-DM) have been implicated in PRL surges. We investigated the temporal relationship between neuronal activity as measured by c-Fos immunocytochemistry in these areas and PRL secretion during early and late pregnancy. Brains were collected at nine time points (24:00, 02:00, 04:00, 06:00, 10:00, 14:00, 16:00, 18:00 and 20:00 h) on days 6–7 and three time points (02:00, 14:00 and 18:00 h) on days 14–15 of pregnancy. Plasma PRL levels determined by radioimmunoassay revealed two surges with peaks at 02:00 and 18:00 h and a trough at 14:00 h on days 6–7, which were absent on days 14–15 of pregnancy. The number of neurons expressing c-Fos in the anterior medial preoptic nucleus, the medial preoptic area and the medial preoptic nucleus, but not the anteroventral preoptic nucleus of the POA, and the VM-DM, showed a semicircadian rhythm which was maximal at 02:00 h or/and 04:00 and 18:00 h and reached the lowest value at 14:00 h, in parallel with the PRL surges in early pregnancy. However, the temporal pattern of c-Fos in these areas was reversed during late pregnancy, with a peak at 14:00 h and low levels at 02:00 and 18:00 h. PRL surges were absent and levels were uniformly low during these times. Neuronal activity in the SCN did not show any correlation with PRL surges. The dorsomedial subdivision of the SCN showed high neuronal activity during the daytime in both stages of pregnancy. Neuronal activity in the ventrolateral subdivision of the SCN was high during the nighttime in early pregnancy, however it exhibited high levels during the daytime in late pregnancy. These results suggest that the two daily surges of PRL secretion during the first half of pregnancy might be related to the temporal rhythm of neuronal activity in the POA and the VM-DM, and a major change in the pattern of neuronal activity in these hypothalamic areas might result in termination of the PRL surges at midpregnancy.

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Electrophysiological Evidence for a Key Control Function of the Medial Preoptic Area in the Regulation of Prolactin Secretion in Cycling, Pregnant and Lactating Rats

Cited by 16 publications

References 14 publications

Alpha‐Oestrogen and Progestin Receptor Expression in the Hypothalamus and Preoptic Area Dopaminergic Neurones During Oestrous in Cycling Rats

Alpha‐Oestrogen and Progestin Receptor Expression in the Hypothalamus and Preoptic Area Dopaminergic Neurones During Oestrous in Cycling Rats

A neural circuitry analysis of maternal behavior in the rat

Semicircadian Rhythms of c-Fos Expression in Several Hypothalamic Areas during Pregnancy in the Rat: Relationship to Prolactin Secretion

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