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Do enkephalins and other endogenous opioids participate in regulation of cancer growth?

100%

Kajdaniuk D., Marek B., Buntner B., Zwirska-Korczala K.

Postępy Higieny i Medycyny Doświadczalnej

2000

vol. 54

issue 5

597-607

Attempts are interesting exploratory trend to define precisely relations between endogenous opioid system and neoplastic process development. Mechanism in which enkephalins and other endogenous opioides could influence on carcer growth is not clear. Several hypothesis were put and presented in the paper.

Neural systems mediating the negative feedback actions of estradiol and progesterone in the ewe

51%

Goodman R. L.

Acta Neurobiologiae Experimentalis

1996

vol. 56

issue 3

727-741

The ewe shows a marked seasonal variation in the effect of ovarian steroids on pulsatile GnRH secretion.In the breeding season progesterone inhibits GnRH pulse frequency, while estradiol suppresses puilse amplitude.In anestrus, both steriods inhibit pulse frequency.The effects of progestrone in both seasons are mediated by endogenous opioid peptides (EOP) that act in the preoptic area (POA) and medial basal hypothalmus (MBH).However, knife cut studies indicate that actions in the MBH are most important.Moreover, blockade of EOP receptors activates GnRH perikarya in the MBH, but not those in the POA.Thus interactions between EOP and GnRH neurons within the MBH may be critical for progesterone negative feedback.The neural systems mediating estradiol suppression of GnRH pulse amplitude in the breeding season are largely unknown, although alpha-adrenergic neurons nay be involved.The seasonal variation in inhibition of GnRH pulse frequency by estradiol is postulated to be mediated by a group of dopaminergic (DA) neurons that have three important properties: (1)they inhibit GnRH pulse frequency; (2) their activity is stimulated by estradiol; and (3) they are functional in anestrus, but not the breeding season.Recent work examining the effects of lesions of DA neyrone and the ability of estradiol to induce Fos inDA cells srongly suggest that DA neurons in the retrochiasmatic area (A15) and POA (A14) have all three characteristics.We thus propose that these DA neurons are responsible for the seasonal variation in the ability of estradiol to inhibit GnRH pulse frequency.

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1 Acta Neurobiologiae Experimentalis

1 Postępy Higieny i Medycyny Doświadczalnej

1 2000

1 1996

1 Buntner B.

1 Goodman R. L.

1 Kajdaniuk D.

1 Marek B.

1 Zwirska-Korczala K.

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Do enkephalins and other endogenous opioids participate in regulation of cancer growth?

Neural systems mediating the negative feedback actions of estradiol and progesterone in the ewe