Pulsatile secretion of gonadotropins and prolactin during the follicular and luteal phases of the menstrual cycle: Analysis of instantaneous secretion rate and secretory concomitance

A potential role of endogenous progesterone in modulation of GH, prolactin and thyrotrophin secretion during normal menstrual cycle

“…[20][21][22] LH (with the exception of an outlier), FSH, oestradiol and progesterone profiles were consistent with most previous descriptions. [23][24][25][26][27][28][29][30][31][32][33] Diurnal profiles of melatonin and cortisol, two hormones primarily regulated by the circadian clock, were found to be essentially similar in the follicular and the luteal phase. Those results are in agreement with most previous studies.…”

Cyclosporine Modifies the Pulsatile Secretory Patterns of Prolactin and Luteinizing Hormone in Normal and Pituitary-Grafted Female Rats

“…These data are in agree ment with those reported by Pohl et al [ 18] in domperidone-induced hyperprolactinemia in ovariectomized rats, although direct effects of domperidone at the hypothala mus cannot be ruled out. However, most reports in the literature showed an inverse relationship between prolac tin and LH [8,9,20], The discrepancies could be due to the above-mentioned differences in blood collection and in the strain used. Also whereas our studies used presum ably stress-free blood withdrawal through chronic venous catheters, other groups obtained blood samples by cardiac puncture under ether anesthesia [26], which greatly alters the circulating concentration of various hormones which include prolactin [8,27] and gonadotropins [28], Hyper prolactinemia induced pseudopregnancy that can in fluence the responses of the hypothalamic pituitary axis to cyclosporine as compared to the control animals in agree ment with previous data from the literature using other stimuli [29].…”

“…Two pituitary glands from adult female rats (retired breeders) from the same strain were implanted under the right kidney capsule according to the method previously described [8], Rats of the same age were sham-operated to serve as controls.…”

“…The drug could change pro lactin and LH secretory patterns by acting on the pitu itary as was described earlier [3]; but effects on the hypothalamus can still predominate. It is well estab lished that prolactin and LH secretory patterns are close ly related [8]. Hyperprolactinemia was associated with diminished, unchanged or increased plasma LH levels [9].…”

Hyperprolactinemia; etiology, diagnosis and treatment alternatives

“…PRL release is inhibited by prolactin inhibiting factors (PIF), mainly dopamine but also by the precursor to GnRH termed gonadotropin associated peptide (GAP) and gamma-amino butyric acid (GABA). The physiological role of the stimulatory effects of gonadotrophin on PRL release is unknown but indicates a new way by which one might influence PRL secretion (16,17). Estrogens and the hormonal environment of pregnancy also stimulate PRL secretion.…”