Effect of Progesterone on the Testosterone and Estradiol Levels in the Hypothalamus of Neonatal Rats

Rhoda, J.; Valens, M.; Edwards, David A.; Roffi, J

doi:10.1159/000242661

Cited by 7 publications

(2 citation statements)

References 12 publications

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“…Evidence also exists that brain aromatase activity is under regulatory control by steroids. Thus, progesterc-ne has been reported to increase (18) or else decrease (19) aromatase activity. Androgens may regulate the basal levels of neural aromatase activity during postnatal development (20) and estradiol and dihydrotestosterone appear to induce brain aromatase in a synergistic manner in adult rats in vivo (21).…”

mentioning

confidence: 99%

Effects of Cyclic AMP and Andre‐gens on in vitro Brain Aromatase Enzyme Activity During Prenatal Development in the Rat

Lephart

Simpson

Ojeda

1992

J Neuroendocrinology

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In the rat, there is a marked but transient increase in hypothalamic aromatase activity during the last week of fetal life. The present study was undertaken to gain insight into the regulation of this developmental pattern. Hypothalamic fragments comprising the medial basal hypothalamus and the suprachiasmatic region (henceforth referred to as preoptic area) were explanted and cultured in serum-free medium for 2 to 5 days. Aromatase activity was measured by the formation of (3) H(2) O, utilizing either [1ß-(3) H]androstene-dione or [1ß-(3) H]testosterone as substrate. Maximal rates of activity were obtained at a saturating concentration of 0.3 μM [1ß-(3) H]testosterone. Confirmation of the identity of the [(3) H]estradiol formed was demonstrated by recrystallization of the derivatized estradiol to constant specific activity following incubation with [1,2,6,7-(3) H]testosterone. In agreement with previous reports, in vivo hypothalamic aromatase activity was negligible before gestational day (GD) 16, increased strikingly by GD19 (>5.0 pmol/h/mg protein) and decreased, thereafter, to low levels at GD22 (∼1.0 pmol/h/mg protein). Medial basal hypothalamus-preoptic area fragments explanted before GD17 failed to develop aromatase activity in vitro. If the tissue was explanted on GD17 or 18 (i.e. when the in vivo rate of activity was increasing), the enzyme activity did not continue to increase, but it was rather maintained for 2 days before decreasing in a manner that closely mimicked the decline observed in vivo. A similar, butimmediate decline was observed when the tissue was explanted on GD19 (i.e. at the time when theactivity peaks in vivo). Exposure of explants to either growth factors (insulin-like growth factor II, epidermal growth factor, and basic or acidic fibroblast growth factor), or steroids (estradiol-17ß, progesterone, testosterone, dihydrotestosterone and corticosterone) failed to either increase aromatase activity before the peak at GD19 or ameliorate its perinatal decline. Increase of Ca(2+) fluxes with the ionophore A23187 or activation of the cyclic AMP, cyclic GMP, or protein kinase C pathways were similarly ineffective, as was angiotensin II, a recently proposed stimulator of neural aromatase. In contrast, aromatase activity was suppressed 2- to 4-fold by activation of the cyclic AMP pathway (with either forskolin or 8-bromo-cyclic AMP) or by the androgens, testosterone and dihydrotestosterone. These results suggest that: 1) the appearance of aromatase activity in the rat hypothalamus before GD17 requires the unfolding of extrahypothalamic events, 2) the increase in aromatase activity that occurs before GD19 also requires extrahypothalamic inputs and does not involve any of the known intracellular signal transduction pathways, and 3) the decline in activity observed after GD19 is regulated within the hypothalamus, and appears to be determined, at least in part, by the activation of cyclic AMP formation. A potential role for androgens is discussed.

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mentioning

confidence: 99%

Effects of Cyclic AMP and Andre‐gens on in vitro Brain Aromatase Enzyme Activity During Prenatal Development in the Rat

Lephart

Simpson

Ojeda

1992

J Neuroendocrinology

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“…Testosterone is necessary for the expression of male sexual behaviour and secondary sex characteristics, as well as controlling some aspects of growth (Rhoda et al 1987). Because Table 2.…”

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confidence: 99%

Effects of progesterone and RU486 on the development and expression of adult male sexual behaviour and gene expression in the amygdala and preoptic area of the hypothalamus

Breton

Austin

Leedy

et al. 2012

Reprod. Fertil. Dev.

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The number of progesterone receptors is greater in the male than female neonatal rat hypothalamus. The aims of the present study were to determine developmental effects of progesterone on the expression of adult male sexual behaviour and whether changes in behaviour were reflected by altered gene expression within the hypothalamic preoptic area (POA) or medial amygdala. Male rats were treated with progesterone (40 µg kg(-1), i.p.), the progesterone receptor antagonist RU486 (40 µg kg(-1), i.p.) or an equal volume of vehicle (10% ethanol, 90% corn oil) on postnatal Days 1-5. Treatment with either progesterone or RU486 inhibited (P ≤ 0.07) the initial expression of consummatory sexual behaviour at 10.5 weeks of age without influencing growth or serum concentrations of testosterone. Sexual interest, as measured by latency to exhibiting mounting behaviour or the number of mounts achieved, was not influenced by treatment with either progesterone or RU486. The effects of treatment with progesterone or RU486 on sexual behaviour were diminished by experience. Microarray analysis of the POA indicated 61 genes that were upregulated and 49 that were downregulated (P ≤ 0.01) following RU486 treatment of male rats. However, the altered expression of selected genes was not confirmed by real-time reverse transcription-polymerase chain reaction. The expression of targeted genes within the amygdala was not influenced by treatment with either progesterone or RU486. Neonatal treatment with RU486, but not progesterone, decreased testes weight (P=0.02) without affecting testes morphology. The results indicate that altering the progesterone environment during a critical developmental period affects the expression of behaviour, but that changes in behaviour are not mirrored by the altered expression of selected genes.

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Fetal Physiology

Broughton-Pipkin¹,

Hull²,

Stephenson³

1994

Marshall’s Physiology of Reproduction

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Effect of Progesterone on the Testosterone and Estradiol Levels in the Hypothalamus of Neonatal Rats

Cited by 7 publications

References 12 publications

Effects of Cyclic AMP and Andre‐gens on in vitro Brain Aromatase Enzyme Activity During Prenatal Development in the Rat

Effects of Cyclic AMP and Andre‐gens on in vitro Brain Aromatase Enzyme Activity During Prenatal Development in the Rat

Effects of progesterone and RU486 on the development and expression of adult male sexual behaviour and gene expression in the amygdala and preoptic area of the hypothalamus

Fetal Physiology

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