The Interaction of the Medial Preoptic Area and the Dorsomedial-Ventromedial Nuclei of the Hypothalamus in the Regulation of the Mating-Induced Release of Prolactin

Gunnet, Joseph W.; Freeman, Marc E.

doi:10.1159/000124079

Cited by 24 publications

(11 citation statements)

References 22 publications

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“…In the present study, the pattern of c-Fos expression in the POA did not differ between the two surges of PRL, although c-Fos measurement alone cannot distinguish one set of neurons from another set in a given area. The VM-DM also are important in stimulating both nocturnal and diurnal surges of PRL [21, 24, 25]. The present study supports this by demonstrating increases in c-Fos expression in these areas during the PRL surges, and loss of activity after midpregnancy.…”

Section: Discussionsupporting

confidence: 85%

“…Electrical stimulation of the ventromedial and dorsomedial nuclei (VM-DM) of the hypothalamus resulted in pseudopregnancy [21, 24] with two daily surges of PRL. Interaction between the medial preoptic area and the VM-DM was necessary for a diurnal but not a nocturnal surge of PRL [25]. Based on these reports, any investigation into hypothalamic control of PRL surges should include the POA, the SCN and the VM-DM.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionsupporting

confidence: 85%

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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“…Dopaminergic neuronal activities in the preoptic area, an inhibitory centre of nocturnal prolactin surges (Gunnet & Freeman, 1984, 1985, and in the arcuate nucleus-median eminence have been reported to be low during the nocturnal prolactin surges (Voogt & Carr, 1981;McKay et ai, 1982;Tomogane et ai, 1987). The present results show that the implant of a low dose of progesterone causes the nocturnal prolactin surges in pubertal rats compared with adult rats.…”

Section: Discussionmentioning

confidence: 99%

“…It seems possible from these results that progesterone induces nocturnal prolactin surges by effectively reducing the activities of dopaminergic neurones during the pubertal period. There is also the possibility that the stimulatory centre in the dorsomedial-ventromedial nuclei (Gunnet & Freeman, 1984, 1985 for nocturnal prolactin surges develops the ability to respond to progesterone during the pubertal period.…”

Section: Discussionmentioning

confidence: 99%

“…Mating and cervical stimulation induce a nocturnal surge of prolactin in ovariectomized rats as well as in pregnant and pseudopregnant rats (Butcher et ai, 1972;Freeman & Neill, 1972;Freeman & Sterman, 1978;Gunnet & Freeman, 1984, 1985. Although the nocturnal prolactin surge appears in the absence of ovarian hormones, its amplitude is modified by these hormones (Freeman & Sterman, 1978).…”

Section: Introductionmentioning

confidence: 99%

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Development of progesterone dependency in the appearance of the nocturnal prolactin surge in immature rats

Tomogane

Yokoyama²

1989

Reproduction

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Organization of projections from the dorsomedial nucleus of the hypothalamus: A PHA-L study in the rat

1996

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The axonal projections of the dorsomedial nucleus of the hypothalamus were investigated by using Phaseolous vulgaris-leucoagglutinin. The main conclusion of this work is that these projections are largely intrahypothalamic, with smaller components directed toward the brainstem and telencephalon. Although the intrahypothalamic pathways are very complex and intermix at various levels, we conclude that dorsomedial nucleus outputs follow three distinct ascending pathways: periventricular, coursing through the hypothalamic periventricular zone; ventral, traveling beneath the medial zone; and lateral, ascending in medial parts of the lateral hypothalamic area. Within the hypothalamus, the most densely innervated areas are the paraventricular nucleus, other dorsal regions of the periventricular zone, the preoptic suprachiasmatic nucleus, and the parastrial nucleus. Other significant terminal fields include the median preoptic, anteroventral periventricular, lateral part of the medial preoptic, and anteroventral preoptic nuclei; and the retrochiasmatic (including perisuprachiasmatic) area. Descending projections follow two pathways that also converge at various levels: a dorsal pathway in the midbrain periventricular system travels through, and primarily innervates, the periaqueductal and pontine gray, and a ventral pathway extends through ventromedial regions of the brainstem. Although sparse, fibers in the later pathway can be traced as far caudally as the nucleus of the solitary tract. The results are discussed relative to the pathways and properties of nearby hypothalamic medial zone nuclei. Dorsomedial nucleus projections are similar to certain other nuclei (e.g., anteroventral periventricular and parastrial) with predominantly intrahypothalamic projections, and different from those arising in the medial zone nuclei (medial preoptic, anterior hypothalamic, ventromedial, and mammillary.

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The Interaction of the Medial Preoptic Area and the Dorsomedial-Ventromedial Nuclei of the Hypothalamus in the Regulation of the Mating-Induced Release of Prolactin

Cited by 24 publications

References 22 publications

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

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

Development of progesterone dependency in the appearance of the nocturnal prolactin surge in immature rats

Organization of projections from the dorsomedial nucleus of the hypothalamus: A PHA-L study in the rat

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