The choice of a model for studying the hypothalamus-pituitary interactions in vitro

Dutt, A.; Gill, Matthew S.; Karanth, Sharada; Lehri, N.; Juneja, H. S.

doi:10.1016/0303-7207(86)90078-x

Cited by 5 publications

(6 citation statements)

References 23 publications

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“…Dutt et al (1986) first used the adult rat PHc cultures as the method of choice to study the inhibitory influence of hypothalamus over the kinetics of secretion of prolactin from the adenohypophyseal lactotrophs in vitro [27]. The authors observed that intact pituitary released comparable amounts of prolactin from 2 to 6 hours in vitro.…”

Section: Hypothalamo Hypophyseal-gonadal Factors Underlying Prolacmentioning

confidence: 99%

“…The prolactin released by the intact pituitary in vitro is a measure of unregulated release whereas that secreted by PHc in vitro is the cumulative effect of physiological PRFs. Dutt et al (1986) assumed that since PHc secreted less prolactin than intact hypophysis in vitro, the difference in the amount released by the two systems would reflect the cumulative hypothalamic PIF activity (HPIA) whereas that secreted by PHc should be a true reflection of hypothalamic PRF activity [27]. Karanth et al (1987) used PHc and PI cultures to validate this hypothesis.…”

Section: Hypothalamo Hypophyseal-gonadal Factors Underlying Prolacmentioning

confidence: 99%

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Prolactin and Male Fertility: The Long and Short Feedback Regulation

Gill-Sharma

2008

International Journal of Endocrinology

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In the last 20 years, a pituitary-hypothalamus tissue culture system with intact neural and portal connections has been developed in our lab and used to understand the feedback mechanisms that regulate the secretions of adenohypophyseal hormones and fertility of male rats. In the last decade, several in vivo rat models have also been developed in our lab with a view to substantiate the in vitro findings, in order to delineate the role of pituitary hormones in the regulation of fertility of male rats. These studies have relied on both surgical and pharmacological interventions to modulate the secretions of gonadotropins and testosterone. The interrelationship between the circadian release of reproductive hormones has also been ascertained in normal men. Our studies suggest that testosterone regulates the secretion of prolactin through a long feedback mechanism, which appears to have been conserved from rats to humans. These studies have filled in a major lacuna pertaining to the role of prolactin in male reproductive physiology by demonstrating the interdependence between testosterone and prolactin. Systemic levels of prolactin play a deterministic role in the mechanism of chromatin condensation during spermiogenesis.

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Section: Hypothalamo Hypophyseal-gonadal Factors Underlying Prolacmentioning

confidence: 99%

Section: Hypothalamo Hypophyseal-gonadal Factors Underlying Prolacmentioning

confidence: 99%

Prolactin and Male Fertility: The Long and Short Feedback Regulation

Gill-Sharma

2008

International Journal of Endocrinology

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“…Prolactin concentrations were measured by radio¬ immunoassay as described previously (Dutt et al 1986). The standard curve for prolactin (NIADDK rat PRL-RP-3) ranged from 10 pg to 12-5ng/assay tube.…”

Section: Methodsmentioning

confidence: 99%

“…The amount of prolactin secreted by the PHC is an index of prolactin secreted by the pituitary in the presence of hypothalamic control, while the amount released by the whole pituitary alone is an index of prolactin secreted without hypothalamic control. The PHC secretes less prolactin than the whole pituitary in vitro (Dutt et al 1986). The difference in the amounts of prolactin secreted by the whole pituitary and the PHC is a measure of hypothalamic restraint of the release of prolactin by the pituitary, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…In this model, the pituitary-hypothalamic complex (PHC) not only retains anatomical orientation in situ but also intact neural linkage of the pituitary to the hypothalamus. According to Dutt, Gill, Karanth et al (1986) the PHC is a good model for studying hypothalamic-pituitary interactions in vitro. The amount of prolactin secreted by the PHC is an index of prolactin secreted by the pituitary in the presence of hypothalamic control, while the amount released by the whole pituitary alone is an index of prolactin secreted without hypothalamic control.…”

Section: Introductionmentioning

confidence: 99%

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Age-related release of prolactin by the pituitary and the pituitary-hypothalamic complex in vitro: an attempt to describe the development of the hypothalamic prolactin-inhibiting and -releasing activities in male rats

Karanth

Dutt²,

Juneja³

1987

Journal of Endocrinology

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We have recently demonstrated that the pituitary hypothalamic complex (PHC) is a good model for studying interactions between the hypothalamus and pituitary in vitro. The amount of prolactin secreted by the PHC is an index of prolactin secreted by the pituitary in the presence of hypothalamic control, while the amount released by the whole pituitary alone is an index of prolactin secreted in the absence of hypothalamic control. The amount of prolactin secreted by the PHC has been regarded as an index of hypothalamic prolactin-releasing activity (HPRA), while the difference in the amounts of prolactin secreted by the whole pituitary and the PHC is the hypothalamic prolactin-inhibiting activity (HPIA). Attempts were made to correlate HPRA and HPIA to the development of serum concentrations of prolactin from days 7 to 77 in male rats. The HPRA increased steadily from days 7 to 56, decreased significantly on day 63 and thereafter remained unchanged until day 77. The HPIA was low on days 7 and 14 and increased steadily up to day 49, with no further significant variations. The developmental patterns of HPRA and HPIA were comparable up to day 49. Serum concentrations of prolactin increased significantly until day 28 and remained fairly constant until day 49. The weight of the pituitary gland increased from 1.0 +/- 0.03 mg (mean +/- S.E.M.) on day 7 to 7.76 +/- 0.32 mg on day 63 and remained unchanged thereafter. The weight of the hypothalamic islet was 31.5 +/- 2.88 mg on day 7, 34.83 +/- 1.45 mg on day 14 and 50.4 +/- 4.01 mg on day 21. After day 21 the weights of the hypothalamic islets were not significantly altered, except on day 49. It was concluded that serum concentrations of prolactin are regulated by interaction or competition between HPRA and HPIA at the level of the pituitary.

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Mechanism delineating differential effect of an antiestrogen, tamoxifen, on the serum LH and FSH in adult male rats

Balasinor

Parte

Gill-Sharma

et al. 2006

J Endocrinol Invest

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Tamoxifen, a synthetic non-steroidal antiestrogen with residual estrogenic activity, administered to adult male rats reduces their fertility. A decrease in the circulating LH and testosterone levels with a transient rise or no change in circulating FSH levels was observed. The present study was carried out to delineate the mechanism causing the differential effect of tamoxifen on circulating gonadotropins by correlating it to changes in the hypothalamic LHRH, pituitary gonadotropins and testicular inhibin/activin. Hypothalamus, pituitary-hypothalamus complex (PHC) and intact pituitary (PI) from control and tamoxifen-treated male rats were superfused in vitro, and pulsatile release of LHRH by hypothalamus and that of LH and FSH by the PHC and PI were studied. Concomitantly, testicular immunoexpression of alpha and betaB subunits of inhibin/activin were studied by immunohistochemistry and enzyme-linked immunosorbent assays (ELISA). At 0.4 mg/kg/day dose of tamoxifen a decrease in mean hypothalamic LHRH and LH pulse frequency from PHC construct was observed. FSH pulse frequency was not affected under the same experimental conditions. At the same dose of tamoxifen, testicular expression of both alpha and betaB subunits of inhibin/activin was upregulated. The study demonstrated that reduced circulating LH levels were due to a decrease in hypothalamic LHRH concentration and in LH pulsatility following tamoxifen treatment. The lack of effect on circulating FSH under the same experimental conditions was likely due to its modulation by inhibin and activin.

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The choice of a model for studying the hypothalamus-pituitary interactions in vitro

Cited by 5 publications

References 23 publications

Prolactin and Male Fertility: The Long and Short Feedback Regulation

Prolactin and Male Fertility: The Long and Short Feedback Regulation

Age-related release of prolactin by the pituitary and the pituitary-hypothalamic complex in vitro: an attempt to describe the development of the hypothalamic prolactin-inhibiting and -releasing activities in male rats

Mechanism delineating differential effect of an antiestrogen, tamoxifen, on the serum LH and FSH in adult male rats

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