Thesis (M.S.) in Animal Sciences--University of Maine, 2005. / Includes vita. Includes bibliographical references (leaves 44-59).

Thesis (M.S.)--Miami University, Dept. of Zoology, 2006. / Title from first page of PDF document. Includes bibliographical references (p. 25-30).

Tierärztl. Hochsch., Diss., 2004--Hannover.

Male stickleback did not show a greater increase in displacement or parental fanning when injected with prolactin than they did when injected with saline solvent alone. Displacement fanning was higher in gonadectomized fish with pituitary activity suppressed by short photoperiod than in gonadectomized fish with an active pituitary under long photoperiods when both groups were treated with the same testosterone concentration. Injection of pituitary fractions into the short photoperiod fish reduced fanning to the levels found under long photoperiods. Normal males under long photoperiod showed significantly higher fanning than any of the gonadectomized groups indicating that methyl testosterone in concentrations used did not fully replace the effects of the normal gonad. Exposure of males to a wide range of testosterone concentrations indicated that a relatively high concentration of testosterone was required for normal fanning. Low levels of fanning occurred after gonadectomy of fish in breeding condition in both "displacement" fanning and parental fanning stages, indicating the gonad was not required for performance of the fanning pattern as such but was required for fanning to reach levels approaching these found in normal fish. No evidence was found that prolactin initiates or maintains the parental fanning cycle. Testosterone however was necessary for normal fanning levels. / Science, Faculty of / Zoology, Department of / Graduate

The role of prolactin in osmotic and ionic regulation of the marine threespine stickleback (Gasterosteus aculeatus L., form trachurus) in fresh water has been investigated in winter (or late autumn) and spring. Sticklebacks in late autumn or early winter, when transferred from sea water to fresh water, suffered a high mortality which could be reduced by prolactin treatment. The fish also displayed a greater fall in plasma osmolality and a smaller fall in urine osmolality than late-spring fish transferred to fresh water in the same way; this seasonal difference was apparently triggered by photoperiodic changes and could be eliminated by prolactin treatment of the late-autumn or early-winter fish. Similarly, a seasonal difference exists in the histological picture of the glomeruli of late-autumn and late-spring sticklebacks, and this difference could be eliminated by prolactin treatment of the former fish. The fall in plasma osmolality in late-autumn and winter fish after transfer to fresh water was paralleled by a rapid drop in plasma sodium and chloride, which could be corrected by a single injection of prolactin given 24 hr before the transfer. Plasma potassium, however, seemed unaffected by prolactin treatment. The evidence suggests that prolactin is essential for freshwater survival of sticklebacks and that prolactin undergoes seasonal changes in secretion associated with photoperiodic changes; the secretion is minimal in the autumn and winter when the fish live in sea water or brackish water, and maximal in the spring and summer when the fish migrate to (or are in) fresh water, to breed. Thus prolactin may be involved in the freshwater migration of sticklebacks. Next, the mechanism of action of prolactin was studied. Prolactin seems to exert its effects (in fresh water) on the three recognized organs of osmotic and ionic regulation in teleosts, viz. kidneys, gills and gut. In the kidneys, prolactin increased urine flow, apparently as a result of an increased GFR. Prolactin reduced the apparent increase in intracapsular space in the glomeruli of the late-autumn and winter sticklebacks, and, consequently, increased the percentage frequency of glomeruli with no evident intracapsular space. The data are interpreted to mean that prolactin rendered glomeruli more functional or more glomeruli fully functionaland, hence, increased GFR. Since the increase in urine flow and GFR was paralleled by a decrease in urine osmolality and urine concentrations of sodium and chloride, prolactin must also increase renal tubular reabsorption of sodium and chloride (A) and/or decrease water reabsorption (B); and since the total renal loss of sodium and chloride did not appear to be significantly increased despite an increase in GFR, A must occur with or without B. Prolactin, however, apparently increased the total renal loss of potassium and did not affect the tubular potassium reabsorption, although there was a suggestion that prolactin actually decreased tubular reabsorption of potassium. In the gills (or other regions around the head), prolactin reduced the net osmotic influx of water and the net loss of sodium, chloride and C¹⁴ (from injected C¹⁴ -inulin); the latter was probably because prolactin reduced the outflux. These changes were accompanied by the behaviour of the gill mucous cells, which were increased in density by prolactin treatment, suggesting a cause-or-effect relationship. In the gut, prolactin reduced water absorption and, at the same time, seemed to reduce the freshwater drinking rate. Thus, it appears that prolactin was able to reduce or prevent osmotic flooding of sticklebacks in fresh water by reducing extrarenal osmotic influx of water and increasing renal loss of water via an increase in GFR and urine flow, and also, possibly, by reducing drinking rate and water absorption by the gut; at the same time, prolactin reduced extrarenal loss of sodium and chloride but did not apparently affect renal loss of the ions, which was small compared to the extrarenal loss. By these mechanisms, prolactin maintained plasma osmolality and sodium and chloride levels after transfer of the fish to fresh water, and, consequently, was able to promote freshwater survival of the fish in the autumn and winter. / Science, Faculty of / Zoology, Department of / Graduate

Effects of oestrogen on prolactin transcription patterns in living pituitary tissue Amanda Louise Patist PhD in the Faculty of Medical and Human Sciences, September 2013, The University of ManchesterOestrogen is a well-known modulator of the transcription and secretion of prolactin as well as having a role in the physiological proliferation and possibly also in pathological hyperplasia of lactotrophs. Our group has studied prolactin gene promoter regulation in single living pituitary cells in Fischer 344 (d2eGFP-hPRL 455) rats, that express a destabilised eGFP reporter gene under the control of a human prolactin genomic fragment, and identified prolactin transcription cycles that occur in a non-circadian and non-synchronised fashion. Pulsatile transcription has been identified in fetal tissue, stabilising during development. Here we assess the effects of physiological and supraphysiological oestrogen exposure in vivo on prolactin transcription in the adult rat. We have established and validated models of both states by evaluating the expression of the hPRL-d2eGFP transgene during the oestrous cycle and in males with long-term oestradiol-releasing implants, respectively. The oestrous cycles of adult female rats were synchronised by IP LHRH injection. A 1.8-fold increase in the number of cells expressing the prolactin transgene at oestrus (n=7) as compared to diestrus (n=5) and a 10.6 fold increase in mean fluorescence per cell was identified by flow cytometry. In males, chronic oestrogen stimulation induced a 2.5-fold increase in pituitary weight, a 5.2-fold increase in number of cells expressing the transgene and 4.4-fold increase in fluorescence per cell, as indicated by flow cytometry (n=3). Immunofluorescence, qPCR and serum analysis confirmed the high-production state of lactotroph cells in both female and male models. 250µm pituitary slices were imaged for 48 hours using time-lapse confocal microscopy and pulsatile fluorescent reporter activity was evident in both female and male models. Interestingly, no significant difference was seen between transcription cycle patterns (timing or amplitude of transcriptional pulses) in individual cells between high and low oestrogen states. Using a novel mathematical model, that calculates transcription rate from fluorescence data, we have been able to study the transcription rates displayed by single cells and the estimated points at which a cell switches from one rate to another. Patterns in switches in transcription rates were similar between high and low oestrogen states, suggesting that individual pituitary cells within the context of tissue, continue to display cyclical patterns of gene expression, in states of both high and low prolactin production. This implies that cyclical transcription is a fundamental property of prolactin gene expression that persists in different physiological states, and that modulation of cycle characteristics is not the mechanism for increased prolactin synthesis in these circumstances.

No description available.

Background: Prolactin-secreting tumours( prolactinomas) are the commonest type of pituitary tumour, accounting for approximately 30 to 40 %% of all pituitary adenomas. Although there is ample epidemiologic and clinic data from Industrialised countries there remains sparse data from Africa. Specifically, the clinical presentation, and hormonal deficiencies and treatment outcomes in the South Africa have not been described. Methods: A retrospective study of all patients with a diagnosis of prolactinoma attending the Endocrine and Pituitary Clinics at Groote Schuur Hospital over a 12-month period, between March 2019-March 2020. Patients folders were reviewed to retrieve the following information: demographic data, clinical presentation, clinical signs, prolactinoma phenotype, hormonal deficiencies, treatment modalities and clinical outcomes. Results: Over a 12-month period 52 patients were included in this study, females 73% (n=38), mean age of all participants was 46.1 ± 14.6 years. A macroprolactinoma was present in 67.3% (n=35) of patients and 32.7% (n=17) of patients had a microprolactinoma. In the macroprolactinoma group: the common presenting symptoms were headache 88.6% (n=33), altered vision 40% (n=14) and , in females, amenorrhoea 63.6% (n=14) but a cranial nerve palsy 17.1% (n=6) and apoplexy 5.7% (n=2) were uncommon. . In the microprolactinoma group the common presenting symptoms included amenorrhoea 75% (n=12), galactorrhoea 70.6% (n=12), headache 64.7% (n=11). On presentation the majority of patients with a macroadenoma had at least one hormonal abnormality with hypogonadism 73.1% (n=19) being most common, followed by hypothyroidism 53.8% (n=14) and hypoadrenalism 30% (n=8). Over 50% of patients with a giant adenoma had panhypopituitarism with hypogonadism in 100%, hypothyroidism in 77.8% (n=7) and hypoadrenalism in 66.7% (n=6). Hormonal deficiencies in the microadenoma group on presentation included hypogonadism 64.7% (n=11), hypothyroidism 35.3 (n=6) and one patient had hypoadrenalism. All patients received medical treatment, however, in the macroadenoma group 4 patients required surgical debulking of the tumour, 3 patients required a ventriculo-peritoneal (VP) shunt for hydrocephalus and 2 patients required radiation. After a median follow-up of 46.5 months, the median prolactin level decreased from 322.5 ug/l (94.0-4282.0) at presentation to 17.5 ug/l (8.6-82.5) at follow-up. In parallel there was a reduction of 12.2 ±9.7 mm in tumour size after a mean of 59.8 ±53.3 months. There was resolution of hypogonadism in 56.4% (n=22), of hypothyroidism in 2.7% (n=2) and hypoadrenalism only resolved in 1 patient. Conclusions: Most patients with a prolactinoma are symptomatic and have at least one hormone deficiency on presentation. With medical management most patients experienced a reduction in prolactin levels and tumour size. . This was associated with the resolution of hypogonadism in the majority, however, hypothyroidism and hypoadrenalism are unlikely to resolve despite a reduction in tumour size.

No description available.

No description available.