TY - JOUR
T1 - Effects of hyperprolactinemia on estrous cyclicity, serum luteinizing hormone, prolactin, estradiol, and progesterone concentrations, and catecholamine activity in microdissected brain areas
AU - Wise, Phyllis M.
PY - 1986/3
Y1 - 1986/3
N2 - The purpose of the present study was to determine the duration of PRL treatment required to suppress estrous cyclicity and preovulatory LH surges and to ascertain whether such treatment affects cyclicity by altering catecholamine activity and/or ovarian steroid secretion. Rats exhibiting 4-day estrous cycles were treated with ovine PRL (oPRL) or vehicle beginning on diestrous day 1 at 0900 h, diestrous day 2 at 2400 h, prqestrus at 0600 h, or proestrus at 1200 h. Jugular veins of rats were cannulated to the level of the right atrium on diestrous day 2. Unrestrained rats were bled on proestrus. Preovulatory LH surges and ovulation were completely blocked, and vaginal cytology remained leukocytic on the expected day of proestrus and estrus when oPRL treatment was begun on diestrous day 1. Such treatment elevated progesterone levels beginning on diestrous day 2 and suppressed the preovulatory rise in estradiol observed on proestrous morning and afternoon in control rats. To determine the effect of oPRL on catecholamine activity, α-methylparatyrosine was administered to groups of oPRL- or vehicle-treated rats at 0900 or 1500 h on diestrous day 1, diestrous day 2, or proestrus. Animals were killed 0, 45, or 90 min later. Norepinephrine and dopamine concentrations were measured in the median eminence, suprachiasmatic nucleus, medial preoptic nucleus, striatum, ventral aspect of the stria terminalis, and posterior pituitary gland by radioenzymatic assay. Controls exhibited increased norepinephrine turnover rates in the median eminence, suprachiasmatic nucleus, and medial preoptic nucleus on proestrous afternoon concomitant with preovulatory LH surges. In contrast, oPRL-treated rats showed no such increase. In addition, median eminence dopamine turnover rates were elevated beginning on the afternoon of diestrous day 1 in oPRLtreated rats compared to control values. No other differences in norepinephrine and dopamine turnover rates were observed in oPRL-treated rats compared with controls in any other brain area on any day examined. Thus, the data indicate that elevated PRL concentrations have profound effects on reproductive cyclicity by disrupting ovarian steroid secretion and essential preovulatory neurochemical events in selected brain areas involved in the regulation of LHRH.
AB - The purpose of the present study was to determine the duration of PRL treatment required to suppress estrous cyclicity and preovulatory LH surges and to ascertain whether such treatment affects cyclicity by altering catecholamine activity and/or ovarian steroid secretion. Rats exhibiting 4-day estrous cycles were treated with ovine PRL (oPRL) or vehicle beginning on diestrous day 1 at 0900 h, diestrous day 2 at 2400 h, prqestrus at 0600 h, or proestrus at 1200 h. Jugular veins of rats were cannulated to the level of the right atrium on diestrous day 2. Unrestrained rats were bled on proestrus. Preovulatory LH surges and ovulation were completely blocked, and vaginal cytology remained leukocytic on the expected day of proestrus and estrus when oPRL treatment was begun on diestrous day 1. Such treatment elevated progesterone levels beginning on diestrous day 2 and suppressed the preovulatory rise in estradiol observed on proestrous morning and afternoon in control rats. To determine the effect of oPRL on catecholamine activity, α-methylparatyrosine was administered to groups of oPRL- or vehicle-treated rats at 0900 or 1500 h on diestrous day 1, diestrous day 2, or proestrus. Animals were killed 0, 45, or 90 min later. Norepinephrine and dopamine concentrations were measured in the median eminence, suprachiasmatic nucleus, medial preoptic nucleus, striatum, ventral aspect of the stria terminalis, and posterior pituitary gland by radioenzymatic assay. Controls exhibited increased norepinephrine turnover rates in the median eminence, suprachiasmatic nucleus, and medial preoptic nucleus on proestrous afternoon concomitant with preovulatory LH surges. In contrast, oPRL-treated rats showed no such increase. In addition, median eminence dopamine turnover rates were elevated beginning on the afternoon of diestrous day 1 in oPRLtreated rats compared to control values. No other differences in norepinephrine and dopamine turnover rates were observed in oPRL-treated rats compared with controls in any other brain area on any day examined. Thus, the data indicate that elevated PRL concentrations have profound effects on reproductive cyclicity by disrupting ovarian steroid secretion and essential preovulatory neurochemical events in selected brain areas involved in the regulation of LHRH.
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U2 - 10.1210/endo-118-3-1237
DO - 10.1210/endo-118-3-1237
M3 - Article
C2 - 3948776
AN - SCOPUS:0022479835
SN - 0013-7227
VL - 118
SP - 1237
EP - 1245
JO - Endocrinology
JF - Endocrinology
IS - 3
ER -