Pup removal suppresses estrogen-induced surges of LH secretion and activation of GnRH neurons in lactating rats

Fukushima, Atsushi; Yin, Ping; Ishida, M.; Sugiyama, Nobuhiro; Ai, Jun

doi:10.1677/joe.1.06728

Cited by 5 publications

(5 citation statements)

References 46 publications

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“…First, in five of them (mPOAd, mPOAv, LHb, SUM, VMH), and even in some sites that did not have significant main effects of or interactions with litter presence (e.g., CG, BSTd, MS, LSvl, PVNp, NAc, LH), a comparison of the unstimulated controls reveals that simply removing the litter produced a 2-6-fold increase in Fos expression. This is not the result of a physiological stress response, because temporary removal of the litter actually decreases maternal glucocorticoid levels, not increases them [24,78,90]. One of the largest increases in Fos after removal of the litter was in the LHb.…”

Section: Fos Expression In Response To Anxiogenic Stimuli Is Modulatementioning

confidence: 94%

Contact with infants modulates anxiety-generated c-fos activity in the brains of postpartum rats

Smith

Lonstein

2008

Behavioural Brain Research

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The postpartum period is associated with many behavioral changes, including a reduction in anxiety, which is thought to be necessary for mothers' ability to appropriately care for infants. In laboratory rats, this reduction in anxiety requires recent contact with pups, but areas of the brain where infant contact influences neural activity to reduce anxiety are mostly unknown. We examined c-fos expression in lactating rats whose pups were removed for 4h to increase mothers' anxiety, or not removed to maintain low anxiety in mothers, followed by exposure to the anxiogenic stimuli of either brief handling or handling followed by exposure to an elevated plus maze. Control animals had their litters removed or not, but no further stimulation. A large number of neural sites traditionally implicated in regulating anxiety in male rats were examined, and similar to what is found in male rats, most showed increased Fos expression after handling and/or elevated plus-maze exposure. Litter presence before testing affected Fos expression due to handling or elevated plus-maze exposure only in the ventral bed nucleus of the stria terminalis, dorsal and ventral preoptic area, ventromedial hypothalamus, lateral habenula, and supramammillary nucleus. Contrary to expectations, prior litter presence was associated with more Fos expression in most of these sites after handling and/or elevated plus-maze stimulation, and only after such stimulation. These sites may be of particular importance for how sensory inputs from infants modulate anxiety and other mood states during the postpartum period.

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Section: Fos Expression In Response To Anxiogenic Stimuli Is Modulatementioning

confidence: 94%

Contact with infants modulates anxiety-generated c-fos activity in the brains of postpartum rats

Smith

Lonstein

2008

Behavioural Brain Research

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“…In rats, Maeda et al (1989) showed that lactation-induced decreases in GnRH/LH secretion are rescued in 18-48 h after pup separation (PS) and are rapidly re-suppressed by subsequent re-exposure of pups. Li et al (1998) also reported the increase of plasma LH by 48-h PS and re-suppression by 24-h re-exposure of pups and Fukushima et al (2006) showed that estrogen responsiveness of LH secretion was restored within 6 h after PS. Although these studies suggest that the proximal cause of these rapid changes in GnRH/LH secretion is the suckling stimulus, the neuroendocrine mechanisms linking the modulation in suckling stimulus and the change in GnRH/LH secretion are not yet fully understood.…”

Section: Introductionmentioning

confidence: 94%

Rapid modulation of hypothalamic Kiss1 levels by the suckling stimulus in the lactating rat

Higo¹,

Aikawa²,

Iijima³

et al. 2015

Journal of Endocrinology

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In mammals, lactation suppresses GnRH/LH secretion resulting in transient infertility. In rats, GnRH/LH secretion is rescued within 18-48 h after pup separation (PS) and rapidly re-suppressed by subsequent re-exposure of pups. To elucidate the mechanisms underlying these rapid modulations, changes in the expression of kisspeptin, a stimulator of GnRH secretion, in several lactating conditions (normal-lactating; 4-h PS; 18-h PS; 4-h PS C1-h re-exposure of pups; non-lactating) were examined using in situ hybridization. PS for 4 h or 18 h increased Kiss1 expressing neurons in both the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC), and subsequent exposure of pups re-suppressed Kiss1 in the AVPV. A change in Kiss1 expression was observed prior to the reported time of the change in GnRH/LH, indicating that the change in GnRH/LH results from changes in kisspeptin. We further examined the mechanisms underlying the rapid modulation of Kiss1. We first investigated the possible involvement of ascending sensory input during the suckling stimulus. Injection of the anterograde tracer to the subparafascicular parvocellular nucleus (SPFpc) in the midbrain, which relays the suckling stimulus, revealed direct neuronal connections between the SPFpc and kisspeptin neurons in both the AVPV and ARC. We also examined the possible involvement of prolactin (PRL). Administration of PRL for 1 h suppressed Kiss1 expression in the AVPV but not in the ARC. These results indicate that suckling stimulus rapidly modulates Kiss1 expression directly via neuronal connections and indirectly through serum PRL, resulting in modulation in GnRH/LH secretion.

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“…GnRH neurones can express Fos (43, 44) but, as in a previous investigation (21), glutamatergic stimulation of LH secretion was not associated with detectable Fos expression in GnRH perikarya. As proposed for rats (23), this lack of Fos expression may result from the threshold for NMA to stimulate GnRH cell function being lower than that necessary to induce detectable Fos expression in these cells.…”

Section: Discussionmentioning

confidence: 68%

Glutamatergic Stimulation of Luteinising Hormone Secretion in Relatively Refractory Male Songbirds

Deviche

Sabo

Sharp

2008

J Neuroendocrinology

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Seasonal breeding in two Sonoran desert passerines, the Cassin's (Aimophila cassinii) and Rufous-crowned (Aimophila ruficeps) Sparrows is thought to be terminated by the development of a decrease in responsiveness to photostimulation, a condition known as relative photorefractoriness. It was predicted that the development of relative refractoriness is a consequence of a decrease in gonadotrophin-releasing hormone (GnRH) synthesis and associated stores of releasable GnRH. This hypothesis was tested by determining the luteinising hormone (LH) responses to the excitatory amino acid glutamate agonist N-methyl-D,L-aspartate (NMA) in males of the two species subjected to photomanipulations aimed at generating five groups: Fully photosensitive with undeveloped testes on short days (8L : 16D); fully photosensitive with developed testes on 13L : 11D; relatively photorefractory with regressed testes on 13L : 11D, and groups with developed testes held on 15L : 9D or 16L : 8D. LH release was stimulated in the Cassin's Sparrow by NMA most in the 8L group; to a lesser, but similar extent in the two 13L groups; and not at all in the 15L and 16L groups. LH release was not stimulated by NMA in any of the photoperiodic regimes in the Rufous-crowned Sparrow. In both species, NMA induced Fos-like immunoreactivity in the anterior and basal hypothalamus, but not in GnRH cell bodies. It is concluded that the development of relative photorefractoriness in Cassin's Sparrows is a consequence of reduced GnRH synthesis, reflected in a reduction in releasable GnRH. The lack of LH response of the Rufous-crowned Sparrows to NMA administration may be a consequence of high responsiveness to handling stress.

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Pup removal suppresses estrogen-induced surges of LH secretion and activation of GnRH neurons in lactating rats

Cited by 5 publications

References 46 publications

Contact with infants modulates anxiety-generated c-fos activity in the brains of postpartum rats

Contact with infants modulates anxiety-generated c-fos activity in the brains of postpartum rats

Rapid modulation of hypothalamic Kiss1 levels by the suckling stimulus in the lactating rat

Glutamatergic Stimulation of Luteinising Hormone Secretion in Relatively Refractory Male Songbirds

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