Prolactin Profiles Research Articles

Circadian rhythms of melatonin, cortisol and prolactin in patients with obsessive-compulsive disorder.

Plasma melatonin, cortisol and prolactin (PRL) levels were measured over a 24-h period in 13 drug-free patients with obsessive-compulsive disorder and in matched healthy subjects. The circadian profiles of melatonin and PRL were altered in patients; the circadian rhythm of cortisol was preserved, although at a higher level compared with normal controls. These changes were significantly related to the severity of the obsessive-compulsive symptoms. Further studies need to clarify the state- or trait-dependent character of these abnormalities.

Treatment of prolactinoma patients with the new non-ergot dopamine agonist roxindol: first results.

We studied the effects of the new non-ergot D2-dopamine agonist roxindol for the treatment of human prolactinomas. Roxindol is a non-ergot drug with additional 5-hydroxytryptamine type 1 A agonist and serotonin reuptake inhibitory activity. Ten patients with prolactin-secreting pituitary adenomas received roxindol three times daily at a dosage of 7.5-30 mg/day for at least 4 weeks according to a prospective protocol. All patients but one had received oral bromocriptine previously without normalization of prolactin levels. Serum prolactin profiles were analyzed once a week during the first month of therapy and at 4-week intervals thereafter. Mean baseline serum prolactin was suppressed from 23,000 +/- 13,600 mU/l (range 1500-141,000 mU/l; 20 mU/l = 1 microgram/l) by 37 +/- 11% after 1 week, by 49 +/- 9% after 4 weeks, and by 65 +/- 11% (n = 8) after 24 weeks of treatment. Serum prolactin was normalized in two patients. A tumor volume reduction of 20-25% was obtained in two subjects. Compared with previous treatment with oral bromocriptine the decrease in serum prolactin was comparable. In contrast, tolerance of roxindol was superior in five of seven patients with major side effects with bromocriptine, including three subjects who had discontinued bromocriptine because of adverse reactions. Four subjects spontaneously reported improvement of psychological and physical performance. One patient had a transient increase of serum transaminases. Thus, for the first time we could show a suppressive effect of roxindol on prolactin secretion in human prolactinomas. Due to its good tolerance roxindol may provide a useful alternative to bromocriptine.

Relationships between broodiness expression laying persistency and concentrations of hormones during the first productive period in turkey hens (Meleagris gallopavo)

The changes in egg production, in broodiness index and in plasma concentrations of LH, prolactin, oestradiol and progesterone were monitored throughout the first period of laying in turkey hens. The hens were subsequently classified according to their ability to express broodiness (33%) and their laying persistency; 25% were out-of-lay by the end of the experiment. A high percentage (67%) of the hens that went out-of-lay had previously been identified as broody. Altogether, a significant (p < 0.05) physiological stage effect was found when comparing prolactin, oestradiol and progesterone data obtained from short and long laying persistency hens and this stage effect was also significant for oestradiol and progesterone data obtained from broody and non-broody hens. Otherwise, plasma LH concentrations decreased slightly but significantly throughout the laying year in all hens but no significant differences between physiological states were observed, although the decrease was more pronounced in the hens that went out-of-lay. Plasma progesterone concentrations remained stable throughout in laying hens but decreased significantly in broody and/or out-of-lay hens. Plasma prolactin concentrations were maximal between the 5th and 12th week of egg production and the levels observed in laying hens that did not become broody or had a long laying persistency were twice those measured in broody and/or out-of-lay hens. In the meantime, plasma oestradiol concentrations were lower and stable in laying hens, whereas they were higher during the first half of the productive period in broody and short laying persistency hens. These results suggest that, under our experimental conditions, the hormonal profiles of prolactin and oestradiol for a given hen during the first 10 weeks of the laying cycle may provide predictive information for future changes in its physiological status. The inverse relationship that was observed here between high early plasma concentrations of oestradiol and laying persistency is original. In addition, the relationship between the ability to express broodiness and high and low early plasma concentrations of oestradiol and prolactin, respectively, in hens submitted to preventive broody treatment has not been reported previously. Furthermore, it seems clear that high initial concentrations in prolactin, far from exerting any deleterious effects on egg production are closely associated with a longer persistency of egg laying.

Dopamine inhibits growth hormone and prolactin secretion in the human newborn.

Dopamine is frequently used in neonatal intensive care for its vasopressor, renal vasodilating, and cardiac inotropic properties. The effect of i.v. dopamine infusion on neonatal pituitary hormone secretion is currently unknown. We observed strikingly low serum concentrations of growth hormone (GH) and prolactin (PRL) during a therapeutic, standardized, isovolumetric, partial exchange transfusion (blood sampling every 20 min for 6 h) in two polycythemic neonates requiring intensive therapy, including continuous dopamine infusion. In addition, the secretion of GH and PRL was studied in three neonates with symptomatic polycythemia (gestational age 34-38 wk; birth weight 2110-2530 g; postnatal age 10-30 h) during a partial exchange transfusion, including an intervening dopamine infusion (8 micrograms/kg/min i.v. for 2 h). The GH and PRL profiles were evaluated by deconvolution analysis. Initially, the three newborns exhibited high-amplitude, pulsatile GH secretion and continuously elevated PRL release. During the dopamine infusion, GH secretion was virtually abolished and PRL release was reduced by at least 50%. Dopamine withdrawal was associated with a rebound release of GH and PRL. Finally, serum GH and PRL concentrations were studied in nine nonpolycythemic newborns (gestational age 31-40 wk; birth weight 1680-4000 g; postnatal age 2-28 d) at the end of a prolonged dopamine infusion (3-5 micrograms/kg/min i.v. for 2-27 d). Within 2 h after dopamine withdrawal, GH and PRL levels increased a median 3-fold and 10-fold respectively. These data concord to indicate that dopamine is a potent inhibitor of GH and PRL secretion in the human newborn.

Effect of pinealectomy and plane of nutrition on wool growth in Merino sheep

The effects of surgical pinealectomy and plane of nutrition on wool growth and plasma prolactin concentrations in young Merino wethers were investigated. In young pinealectomized wethers maintained at a low live weight under conditions of minimal stress, the decline of conditioned clean wool production on midside patches was slowed when compared to pineal-intact controls. This difference appeared to be due in part to the observed greater secondary wool follicle density in the pinealectomized wethers; mean fiber diameter was affected to a smaller extent, while staple length growth rate was not significantly altered. Circulating prolactin profiles showed a seasonal variation (high in summer, low in winter) in both pinealectomized and control wethers. There was no difference in wool production between pinealectomized and control wethers when the diet of the same wethers was subsequently supplemented with formaldehyde-treated cottonseed meal. While the role of melatonin in the regulation of wool growth remains to be determined, it is suggested that the hormone may have a transient effect on wool production in young wethers under conditions of limited nutrition, but not at higher nutritional levels, and that melatonin may be involved in partitioning of nutrients to the wool follicle.

Nocturnal pituitary hormone and renin profiles during chronic heat exposure.

To establish the principal endocrine systems involved in the initial adaptation to chronic passive heat exposure, responses of the hydromineral and pituitary systems were compared. Nocturnal plasma profiles of growth hormone, prolactin, thyrotropin, and plasma renin activity were determined during a period of prolonged heat exposure designed to simulate a hot climate. Two groups of six male subjects (G1 and G2) were kept for 11 days in a climatically controlled apartment. The G1 group was exposed to 20 degrees C throughout the study, and the G2 group was exposed to 20 degrees C for 5 days and to 35 degrees C for the following 6 days. Blood was collected continuously during the 1st and 10th nights from 2300 to 0700 h and was sampled in 10-min aliquots for hormone analysis. Heat exposure increased the nocturnal mean core temperature (P < 0.02) and stimulated plasma renin activity (P < 0.01) but had little effect on the pituitary hormones except for a small increase in prolactin (P < 0.05). For the G1 group there was no change in hormone profiles. These results demonstrate that the principal initial endocrine system involved in acclimatization to passive heat exposure is the renin-angiotensin system, reflecting counteractive measures against salt and water losses. In contrast, 5 days of continuous heat exposure does not provoke metabolic changes, indicated by the small effect on pituitary hormone profiles.

Endogenous Catecholamines Modulate Growth Hormone Release in the Conscious Rat During Hypoglycaemia but not in the Basal State

To investigate the role of endogenous catecholamines and 5-hydroxytryptamine in the control of growth hormone (GH) secretion, secretory profiles of GH and prolactin were measured in conscious, male rats following intravenous administration of either 1) alpha 2 antagonist idazoxan 2 mg/kg, a dose that blocked alpha 2 agonist induced GH rise, 2) alpha 1 antagonist prazosin 1 mg/kg, 3) non-specific beta-blocker propranolol 1.5 mg/kg, a dose that prevented beta 2 agonist (salbutamol) induced inhibition, 4) serotonin antagonist cyproheptadine 0.5 mg/kg, a dose that inhibited serotonin agonist quipazine induced GH rise, or 5) control. No drug altered mean GH or prolactin levels and pulsatile GH release persisted. Unilateral injections of prazosin, propranolol and idazoxan were made into the medial basal hypothalamus and preoptic-anterior hypothalamic area and of cyproheptadine into the medial basal hypothalamus, all with no effect on short-term GH release. GH and prolactin secretory profiles were measured after giving rats 6 units/kg intravenous insulin. Blood glucose levels fell to less than 50% basal. Hypoglycaemia caused a non-significant 30% fall in mean 2 h GH. Intravenous idazoxan, prazosin, propranolol and cyproheptadine (doses as in first study) did not modify the blood glucose fall, but idazoxan produced a significant reduction of mean GH compared to insulin alone (4 +/- 1.1 ng/ml SEM, idazoxan/insulin versus 16 +/- 5.6 ng/ml, saline/insulin). The lack of an effect of alpha- and beta-blockers on normal, pulsatile GH release is against a role for endogenous catecholamines in controlling this release.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of phencyclidine on 5-hydroxytryptophan- and suckling-induced prolactin release

The effects of acute and chronic exposure to phencyclidine (PCP) on the regulation of prolactin (PRL) secretion were examined. Female Sprague-Dawley rats were injected with PCP (10 mg/kg) or saline for 14 days, or just prior to the administration of the serotonin precursor, 5-hydroxytryptophan (5-HTP). A single injection of PCP had no effect on the 5-HTP-induced rise of plasma PRL levels. In contrast, chronic administration of PCP facilitated the release of PRL induced by 5-HTP. Peak plasma PRL levels were more than 3-fold higher after chronic PCP. The acute effect of PCP on suckling-induced PRL release was also examined. PCP delayed the rise of plasma PRL levels by suckling. The magnitude and profile of PRL, however, were similar to saline controls. The pups of PCP-treated dams failed to obtain milk during the suckling episode. Exogenous oxytocin restored the milk ejection reflex in PCP-treated dams. PCP had no effect on basal PRL release from anterior pituitary cells in vitro, and failed to alter the effects of TRH or dopamine. Conclusions: (1) chronic, but not acute, administration of PCP facilitates the 5-HTP-induced release of PRL, (2) acute exposure to PCP delays the suckling-induced rise in PRL and appears to inhibit oxytocin release. These data demonstrate that both acute and chronic PCP may alter the regulation of PRL release, likely through an indirect central mechanism.

Characteristics of somatotropin and prolactin profiles in young dairy sires before and after a 72-hour fast during different seasons.

Serial blood samples were collected from young (mean = 275 d of age) AI sires at 20-min intervals for an 8-h period before and after a 72-h fast. Samples were collected from four different groups of young sires in January (n = 23), April (n = 31), July (n = 27), and October (n = 24). Samples were collected for only 6 h for the July group. Plasma somatotropin (ST) and prolactin (PRL) data were analyzed by PULSAR, a computerized peak detection program. The PULSAR parameters, except for number of peaks detected, were not different (P greater than .05) when calculated using data from the entire 8-h period or just the first 6 h. Because some endocrine characteristics as defined by PULSAR were influenced by season, deviated values were calculated for those characteristics within seasonal groups by subtracting the mean of that group from each individual observation for all PULSAR parameters. Number of ST peaks was correlated (P less than .01, r = .26) with USDA pedigree index (PI) for fat yield (PIF), sire predicted transmitting ability for fat (PTAF; P less than .01, r = .30), Northeast AI Sire Comparison (NEAISC) PIF (P less than .05, r = 24), and sire PTAF (P less than .01, r = .33). No ST pulsatile characteristics after fasting were correlated (P greater than .05) with PI. Prolactin peak length was negatively related to USDA PIF (P less than .05, r = -.23) before fasting and positively correlated (P less than .05, r = .26) after fasting.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of light intensity on circadian profiles of melatonin, prolactin, ACTH, and cortisol in pigs.

Eleven crossbred barrows were housed in environmentally controlled rooms with an 8-h photoperiod. Pigs in one room received control illumination of 113 1x (CON; n = 6), and pigs in the other room received intense illumination of 1,783 1x (INT; n = 5) fluorescent light. Pigs were given at least 20 d of exposure to the environment before blood samples were taken every 3 h for 48 h. Data were analyzed by split-plot analysis of variance. Except for prolactin, no treatment x time interactions were noted for the hormone profiles evaluated (P greater than .10). Pigs in INT had greater (P less than .05) concentrations of prolactin in serum than pigs in CON at every sampling time. Concentrations of ACTH and cortisol in plasma were similar for INT (33.9 +/- 3.2 pg/mL of ACTH and 24.4 +/- 3.4 ng/mL of cortisol, respectively) and CON (34.9 +/- 3.0 pg/mL of ACTH and 31.3 +/- 3.1 ng/mL of cortisol, respectively). Within the INT treatment, serum melatonin concentrations were more than doubled (P less than .05) during darkness (66.8 +/- 9.3 pg/mL) compared with during light (30.4 +/- 9.3 pg/mL); however, within the CON treatment, concentrations during light and darkness did not differ (38.4 +/- 9.3 pg/mL and 42.9 +/- 9.3 pg/mL, respectively). Results indicate that light of greater intensity is required to entrain circadian rhythms of melatonin in serum of pigs. Furthermore, pigs may respond to bright light with greater secretion of prolactin, even under constant duration of photoperiod.

Radioreceptor assay of serum prolactin using nitrocellulose membrane-immobilized mammary prolactin receptor

Triton-solubilized rabbit mammary prolactin (PRL) receptor was purified by concanavalin A-agarose chromatography and immobilized on a nitrocellulose membrane. Using the membrane-bound receptor and bovine serum, the serum level of PRL was determined by radio-receptor assay (RRA). The displacement curve, obtained by serial dilutions of the serum, was parallel to that obtained in the range of 0.4 and 20 ng/ml of standard bovine PRL. Serum could be included in concentrations up to 16% of the assay buffer and, thus, the detection limit of serum PRL was about 2.5 ng/ml. PRL in the serum was determined by radioimmunoassay (RIA). The ratio of the RIA and RRA estimates of PRL was 0.99 ( r = +0.99, n = 55). The gel-filtration profile of serum PRL was identical to that obtained by RIA. It was concluded that membrane-bound receptor can be used for the determination of serum PRL.

Identification of a seasonal elevation in daytime melatonin levels associated with the rut in fallow bucks (Dama dama): The effect of day length and exogenous melatonin

The timing of the seasonal reduction in voluntary food intake and hormonal changes associated with the rut were investigated in mature fallow bucks subjected to artificial long-day exposure with and without superimposed melatonin-releasing implants. Circulating testosterone profiles and the period of inappetence, signalling the onset of the period of reproductive activity in untreated bucks under natural photoperiod, were phase-advanced in both treatment groups. In the long-day treated group, these profiles were phase-advanced by 1 week, while in the long-day + melatonin group, the phase advance was 6 weeks compared to the controls. Circulating daytime melatonin, elevated in all three groups, corresponds with seasonal changes in circulating testosterone levels associated with the rut. Prolactin profiles followed ambient photoperiod, being high during natural or artificial long days and low during natural short days. Exogenous melatonin administered during long-day exposure initiated a rapid and reversible decrease in circulating prolactin levels. The elevation in plasma melatonin could not be separated temporally from the seasonal testosterone peak by exposure to long days or to exogenous melatonin. However, this daytime melatonin profile was abolished by the ablation of circulating testosterone following immunization against luteinizing hormone releasing hormone (LHRH). The presence of this endogenous melatonin during daylight was observed only during the rut, as measured in two radioimmunoassays and confirmed by mass spectrometry. It is likely that both testosterone and melatonin influence the onset of the seasonal rut in fallow bucks.

A Daily Prolactin Rhythm Persists in the Ewe, Foetus and Newborn Lamb After Maternal Pinealectomy in Late Gestation

Abstract We have investigated the effect of maternal pinealectomy between 104 and 120 days gestation on the daily rhythm in plasma prolactin concentrations in the ewe, foetus and newborn lamb. There was a 24 h prolactin rhythm present in both the intact (n = 4) and pinealectomized (n = 4) ewes. Plasma prolactin concentrations were highest at 2100 h (i.e. 2 h after lights off) and a daily prolactin rhythm was present until at least 24 h before delivery. The mean 24 h foetal plasma concentration of prolactin was significantly higher (P<0.001) in the pinealectomized (35.3 + 1.9 mug/1) than in the intact group (6.9 +/- 0.6 mug/1). There was a significant 24 h rhythm in foetal prolactin concentrations and the timing of the daily peak (2100 h) was the same in the foetuses of intact and pinealectomized ewes. During the first 10 weeks after birth there was a significant effect of time of day on prolactin concentrations but the 24 h prolactin profile was significantly different in the lambs delivered to pinealectomized ewes than in the lambs delivered to intact ewes. In the lambs delivered after maternal pinealectomy, plasma prolactin concentrations were higher between 1900 and 2300 h than between 0700 and 1100 h, whereas in lambs delivered to intact ewes, prolactin concentrations were higher at 0100 h than between 1500 and 1700 h. We conclude that the ontogenesis of the daily rhythm in foetal and newborn lamb plasma prolactin concentrations is not dependent on a daily melatonin signal from the ewe.

Plasma Patterns of Prolactin, Progesterone, and Estradiol during Early Pregnancy in Aging Rats: Relation to Embryonic Development1

Regularly cyclic, middle-aged female rats exhibit a decreased incidence of fertility, and those females that are fertile produce smaller litters. This decreased litter size is directly related to a reduced number of normal blastocysts available for implantation. Recent evidence indicates that embryonic abnormalities in middle-aged rats become apparent as early as Day 2 of pregnancy. Inasmuch as the semicircadian secretion of prolactin (PRL) is essential for the rescue of corpora lutea during early gestation and luteal production of progesterone (P) and estradiol (E2) in sufficient quantities is obligatory for embryonic development and implantation, the present study examined the profiles of plasma PRL, P, and E2 during the first 3 days of pregnancy in both young and middle-aged rats and assessed the embryonic development in these same animals. Regularly cyclic, middle-aged (9-11 mo) and young (4-5 mo) rats were cannulated via the right jugular vein on Diestrus Day 2 and mated with fertile males on proestrus. The next morning, sperm in the vaginal lavage confirmed mating, and that day was designated Day 1 of pregnancy. Beginning at 1400 h on Day 1 and continuing to 2400 h on Day 2, serial blood samples were taken at 2-h intervals for PRL assay. In the first experiment, samples were also collected at 8-h intervals during Days 1-3 for measurement of plasma P.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyrotropin and prolactin responses to ECT in schizophrenia and depression

Thyroid stimulating hormone (TSH) and prolactin (PRL) plasma levels were studied during electroconvulsive therapy (ECT) in five schizophrenic patients in a simulated ECT (SECT) controlled experimental design. The data were compared to those obtained from a group of 10 depressed patients treated with ECT. In the schizophrenic group, both PRL and TSH increased significantly during ECT compared to SECT, as they did in the depressive group during ECT. Thus, the hormonal TSH and PRL profile during ECT is similar in schizophrenia and depression. It is concluded that the changes in TSH and PRL induced by ECT are specifically linked to the current or the seizure, and are not related to the type of psychopathology.

Neuroendocrine rhythms and sleep in aging men

To delineate the physiological effects of aging on basal levels and temporal patterns of neuroendocrine secretions, the 24-h profiles of cortisol, thyroid-stimulating hormone (TSH), melatonin, prolactin, and growth hormone (GH) levels were simultaneously obtained at frequent intervals in eight healthy, active elderly men, age 67-84 yr and in eight young male adults, age 20-27 yr. The study was preceded by an extended period of habituation to laboratory conditions, and sleep was polygraphically recorded. Mean cortisol levels in the elderly were normal, but the amplitude of the circadian rhythm was reduced. Circulating levels of daytime and nighttime levels of both TSH and GH were greatly diminished in old age. In contrast, prolactin and melatonin concentrations were decreased during the nighttime only. The circadian rises of cortisol, TSH, and melatonin occurred 1-1.5 h earlier in elderly subjects, and the distribution of rapid-eye-movement stages during sleep was similarly advanced, suggesting that circadian timekeeping is modified during normal senescence. Despite perturbations of sleep, sleep-related release of GH and prolactin occurred in all elderly men. Age-related decreases in hormonal levels were associated with a decrease in the amplitude, but not the frequency, of secretory pulses. These findings demonstrate that the normal process of aging involves alterations in the central mechanisms controlling the temporal organization of endocrine release in addition to a reduction of secretory outputs.

Plasma profiles of adrenocorticotropic hormone, cortisol, growth hormone and prolactin in patients with untreated parkinson's disease

Plasma profiles of prolactin, growth hormone, adrenocorticotropic hormone (ACTH) and cortisol were evaluated in a group of untreated patients with idiopathic Parkinson's disease and a group of healthy age-matched controls. Plasma integrated concentrations of all hormones except prolactin were significantly lower in the patients as compared with the controls; however, prolactin nocturnal peak concentration was significantly elevated in the patients; nocturnal growth hormone levels were significantly reduced in the Parkinson group; ACTH and cortisol plasma concentrations were also consistently lower during most of the day in the patients with Parkinson's disease. These data confirm the presence of a hypothalamic disturbance in patients with idiopathic Parkinson's disease, which can affect pituitary function.

Diurnal profiles of LH, prolactin and progesterone and their inter-relationships in ewes in high or moderate levels of body condition

Relationships between circulating progesterone profiles and those of the luteotrophic hormones luteinising hormone (LH) and prolactin were examined at different times of day in two groups of 19 and 18 Greyface ewes in a high level of body condition (H; condition score ≥3.5) or moderate level of condition (M; condition score 2.5/2.75). These levels of body condition were maintained from 4 weeks before mating at a synchronised oestrus until slaughter at approximately 5 weeks post mating. On day 10 post mating, blood samples were collected at 20-min intervals during two periods of 6 h during the day (10:00–16:00) and night (22:00–04:00). All samples were assayed for progesterone, LH and prolactin. There were no significant effects of level of body condition on mean ovulation rates, pregnancy rates and ova wastage rates or on progesterone, LH and prolactin profiles. Mean progesterone concentrations were lower during the day than at night (3.2 vs. 3.6 ng ml −1; P < 0.001) while LH concentrations were higher (0.74 vs. 0.66 ng ml −1; P < 0.001) and prolactin concentrations were unaffected (12.8 vs. 11.9; NS). There was a higher incidence of progesterone pulses (0.24 vs. 0.17 pulses h −1; P < 0.01) and a lower prolactin pulse frequency (0.22 vs. 0.33 pulses h −1; P < 0.01) during the day than at night. Whereas the LH pulse frequency was similar during the two periods for M ewes (0.21 vs. 0.22 pulses h −1; NS), it was higher during the day in H ewes (0.25 vs. 012 pulses h −1; P < 0.01). LH and progesterone concentrations were significantly correlated but not prolactin and progesterone concentrations. Body condition did not affect the mean magnitude of the increase in progesterone concentrations following LH pulses. We conclude that LH profiles, but not prolactin profiles, directly influence progesterone profiles and that diurnal variations in LH pulse frequency are likely to be associated with diurnal variations in progesterone supply to the uterus and oviduct. We suggest that the nocturnal reduction in LH pulse frequency in H ewes could have detrimental effects on reproductive performance.

Evidence of Altered Dopaminergic Modulation of Prolactin and Thyrotropin Secretion in Patients with Polycystic Ovary Syndrome

In order to evaluate the functional activity of the tubero-infundibular dopaminergic system in polycystic ovary syndrome (PCOS), we analysed the prolactin (PRL) and thyrotropin (TSH) responses to the dopamine antagonist sulpiride. We studied 8 euthyroid women affected by PCOS and 7 normal women. The mean baseline PRL values were normal in both groups. After sulpiride administration the incremental area under the PRL profile in PCOS was significantly lower than in normal subjects (p less than 0.01). The mean basal plasma TSH levels were significantly higher in the PCOS than in the control group (p less than 0.01). After sulpiride administration the incremental area under the TSH profile was significantly lower in PCOS patients than in normal women (p less than 0.01). The higher basal plasma levels of TSH, the blunted response of PRL and the lack of response of TSH to sulpiride in PCOS suggest a relative decrease of the dopaminergic activity in PCOS patients.

Somatotropin and prolactin profile characteristics in proven AI dairy sires.

Blood samples were collected at 20-min intervals for 8 h from 16 Holstein sires, each of which had U.S. Department of Agriculture (USDA) and Northeast AI Sire Comparison (NEAISC) progeny test evaluation data available. Plasma somatotropin (ST) and prolactin (PRL) concentrations were measured, and resulting endocrine profiles were analyzed by PULSAR, a microcomputer-based hormone peak-detection program. The number of ST peaks during the sampling period was negatively related to USDA Predicted Transmitting Ability (PTA) for fat yield, milk, and fat product value (PTA+), and for milk, fat, and protein product value (PRO+), and ST peak length was negatively related to PTA for protein percentage (PTA %P). Interpeak interval for ST was positively related to NEAISC percentage of Protein Deviation (%P). Prolactin peak length was correlated positively with both USDA PTA %P and NEAISC %P, and peak frequency was correlated positively with NEAISC %P. Interpeak interval for PRL was related positively to NEAISC Milk and Fat Deviations. Area under PRL profile was negatively related (P less than .05) to USDA PTA+ and PRO+, and NEAISC Fat Deviation and Dollars. The results indicated that endocrine traits in mature dairy sires are correlated with genetic merit for economically important production traits and suggested that such profile characteristics may be useful in selecting young sires for progeny testing programs.