P36 A 1 and 5 year outcome analysis of epilepsy surgery in adults and children

Objectives

To evaluate the efficacy of epilepsy surgery at 1 year following surgery and to assess sustainability of seizure control at 5 years post-surgery. To find prognostic factors for good surgical outcomes.

Design

Retrospective case notes analysis.

Subjects

82 consecutive patients operated on for epilepsy by a single surgeon between 2008–2013.

Methods

Patients were identified in pre-existing hospital databases and included if 5 year follow-up was available. Their clinical records were accessed via the electronic patient records system at each site. The Engel Classification was used to grade seizure outcome at years 1 and 5 post-surgery. We classified Engel Class I and II as a good outcome and Engel class III and IV as a poor outcome. Case notes were also examined to find prognostic factors for a good long-term surgical outcome.

Results

86.4% of patients had a good outcome 1 year post-surgery and 77.9% had a good outcome at 5 years. The surgery site (temporal or otherwise) and the presence of a good outcome at year one were found to contribute significantly to odds of a good outcome at year 5. The ability to wean off medication is also commonly an important factor for patients and 24.4% of patients were AED free at 5 years.

Conclusions

Surgery is an effective management option for intractable epilepsy in suitably selected patients with complete or near complete seizure cessation in about 80% of the patients and about a quarter of the patients no longer requiring AEDs.

TP3-2 Epilepsy surgery outcomes in a paediatric population – a single centre 10 year experience

Objectives

To analyse the efficacy of epilepsy surgery in reducing the burden of seizures in a paediatric population – a single centre 10 year experience.

Design

Single centre retrospective review of medical records.

Subjects

74 consecutive paediatric patients who underwent epilepsy surgery between 2008–2017 by one neurosurgeon at a single centre.

Methods

Seizure history, pre-operative investigations, surgical interventions, seizure outcomes, complications and long term anti-epileptic drug (AED) use were evaluated. Seizure outcomes at 1 year post surgery to the last available follow up (up to 5 years) were documented and classified using the Engel System. Engel I and II were classified as a good seizure outcome and Engel III and IV were classified as a poor seizure outcome.

Results

The mean duration of follow up was 41 months. 62.2% of patients achieved seizure freedom (Engel I) at their latest follow up, with 82.4% of patients achieving a good seizure outcome (Engel I/II). 13.5% of patients achieved worthwhile improvement (Engel III) and only 4.1% of patients had no worthwhile improvement in seizure burden (Engel IV). More favourable outcomes were observed in children with temporal lobe epilepsy. Post-surgery AED use was reduced or discontinued in 41.4% of all patients; 41.4% of the 29 patients with AED data at their 5 year follow up were completely free of AEDs.

Conclusions

Epilepsy surgery is an efficacious treatment with low morbidity and no mortality that is underutilised in children with medically intractable seizures.

Sexual experience and temperament affect the response of Merino ewes to the ram effect during the anoestrous season

In seasonally anoestrous ewes of many breeds, the introduction of rams triggers an increase in gonadotrophin secretion that induces ovulation, a phenomenon known as the 'ram effect'. The ram effect is a practical method for mating ewes outside the natural breeding season, and also can provide synchronised lambing, but the variability of the response, especially in young animals, reduces its potential for widespread application. The aim of our study was to assess two factors that are thought to contribute to the variability in young ewes: temperament and sexual experience. We used anovulatory ewes from a flock that had been genetically selected for 'calm' or 'nervous' temperament and compared the endocrine and ovarian responses to the ram effect in four groups (each n=15): 'calm' and parous (3-6 years old); 'calm' and nulliparous (2 years old); 'nervous' and parous; and 'nervous' and nulliparous. Parous ewes, independently of their temperament, exhibited a faster endocrine response and a higher proportion of females cycling after ram introduction than nulliparous ewes. 'Nervous' ewes exhibited a higher proportion of females cycling after ram introduction than calm ewes, but only in the nulliparous group. We conclude that temperament exerts little influence on the response to the ram effect in sexually experienced ewes, and that females of 'nervous' temperament appear to respond better when sexually 'naive'. Both sexual experience and temperament need to be taken into consideration when flock management involves the ram effect. Finally, some ewes were cyclic at ram introduction, yet exhibited an increase in LH secretion even in the presence of high concentrations of progesterone. The mechanism by which the inhibitory effect of progesterone on LH secretion was bypassed needs to be clarified.

242. Reproductive performance of Australia Cashmere goats supplemented with lupin grain

The productivity of Cashmere goats depends on their reproductive performance, which, in turn, depends on their level of nutrition. Ovulation rate and pregnancy in sheep are both affected by nutrition, but little is known about the response of female goats (does) to supplementary feeding. The lupin group (n = 40) received 250 g lupin per head per day in addition to pasture whereas the control group (n = 40) received no nutritional supplement. Both groups were synchronised for 17 days with intravaginal progestagen pessaries. The supplement was fed for 21 days, commencing 7 days before the bucks were introduced and intravaginal pessaries were removed (Day –2). Does were expected to ovulate 2 days later on Day 0 and the bucks were removed on Day 3. Blood was sampled for progesterone every 3 days from buck removal (Day 3) until Day 18. Ovulation rate was assessed by trans-rectal ultrasonography on Day 13 and pregnancy was diagnosed by trans-abdominal ultrasonography on Day 61 of the experiment. Does supplemented with lupins had a numerically higher ovulation rate than does fed only on pasture, but this difference was not significant (1.76 ± 3.21 v. 1.52 ± 3.79; P > 0.05). Similarly, there was no difference in the numbers of does conceiving to the first service between the lupin and control group (89% v. 94%; P > 0.05). Progesterone concentrations on Day 12 were higher in does supplemented with lupins than does fed only pasture (6.29 ± 0.27 ng/mL v. 5.41 ± 0.27 ng/mL; lupin and control group; P < 0.05). In conclusion, lupin supplementation induced a numerical increase in ovulation rate but this difference failed to reach significance. Does supplemented with lupins had higher concentrations of progesterone during early pregnancy, which is the opposite effect to that previously reported in sheep.

Colostrum quality of ewes of calm temperament is not responsible for low lamb mortality

Perinatal lamb mortality is a serious issue for the sheep industries. Starvation is implicated in many of these lamb deaths. Ewes with a calm temperament lose significantly fewer lambs than ewes with nervous temperament, particularly in the critical first 3 days after birth. Colostrum provides essential nutrition to neonatal lambs. This research set out to determine whether ewe temperament affects the quantity and quality of colostrum that ewes produce. Calm temperament was found to have an influence on the viscosity of colostrum 6 h after birth. High variability in all aspects of colostrum production were found in the study and may be a limiting factor in lamb survival in certain circumstances. There is little evidence, however, to suggest a strong association with ewe temperament and is therefore unlikely to explain the lower lamb mortality that is reported to occur among calm ewes.

Conditionally immortal neuroepithelial stem cell grafts restore spatial learning in rats with lesions at the source of cholinergic forebrain projections cholinergic forebrain projections Conditionally immortal neuroepithelial stem cell grafts restore spatial leaming in rats with lesions at the source of cholinergic forebrain projections

Purpose: Loss of cholinergic projections from the basal forebrain (BF) to the cortex and from the medial septal area (MSA) to tbe hippocampus is a reliable correlate of cognitive deficits in aging and Alzheimer's disease (AD). We assessed the capacity of grafts of the conditionally immortal MHP36 clonal stem cell line to improve spatial learning in rats showing profound deficits after lesions to these projections. Methods: Rats were lesioned by infusions of S-AMPA unilaterally into BF or bilaterally into both BF and MSA. MHP36 cells were implanted ipsilaterally in cortex or basal forebrain two weeks after unilateral BF lesions, and in cortex and hippocampus bilaterally six months after bilateral BF-MSA lesions. Intact and lesion-only controls received vehicle. Six weeks later rats were assessed in spatial learning and memory tasks in the water maze, and then perfused for identification of grafted cells by beta-galactosidase immunohistocheniistry. Results: Lesioned rats with MHP36 grafts, whether implanted two weeks or six months after lesioning, learned to find a submerged platform in the water maze as rapidly as intact controls, and showed a strong preference for the platform quadrant on probe trials, whereas lesioned controls were impaired in all measures. Grafted cells of both neuronal and glial morphologies, migrated away from cortical implantation sites in BF Lesioned rats to the striatum, thalamus and basal forebrain lesion area. Cells implanted in basal forebrain showed a similar distribution. In rats with bilateral BF-MSA lesions, grafts implanted in the hippocampus migrated widely through all layers but cortical grafts largely escaped up the needle tract into the meninges. Conclusions: Although MHP36 grafts were functionally effective in both lesion models, the site and age of lesions and site of implantation influenced the pattern of engraftment. This flexibility encourages the development of conditionally immortal human stem cell lines with similar capacities for functional repair of variable neuronal degeneration in AD or aging.

Functional reconstruction of the hippocampus: fetal versus conditionally immortal neuroepithelial stem cell grafts

Late fetal CA1 hippocampal grafts and stem cell grafts from the conditionally immortal MHP36 clonal line derived from the H-2Kb-tsA58 transgenic mouse neuroepithelium both improved spatial deficits in rats with ischaemic CA1 damage induced by four-vessel occlusion (4VO). However, the distribution of fetal and MHP36 grafts differed. Fetal cells lodged in clumps around the implant sites and along the corpus callosum, whilst MHP36 grafts infiltrated the area of CA1 ischaemic damage, achieving apparent architectural reconstruction of the hippocampus. The migration of MHP36 cells is damage-dependent. Few cells were found in intact brain; after 15 min of 4VO cells repopulated only the discrete area of CA1 cell loss, whereas with more extensive damage after 30 min occlusion cells migrated to all hippocampal fields and to cortex. A higher proportion of grafted MHP36 cells differentiated into neurons in the host CA1 field than grafts of striatal or cortical expanded cell populations. Cortical population grafts were as effective as MHP36 grafts in improving water maze learning, whereas striatal or ventral mesencephalic cells were ineffective, indicating a degree of stem cell specificity. The efficacy of MHP36 cells extends to primates. In marmosets with profound impairments in conditional discrimination tasks after lesions of the CA1 field, MHP36 cells improved performance as effectively as fetal grafts and migrated evenly through the CA1 field, in contrast to clustered fetal cells. These findings suggest that MHP36 stem cell grafts are as effective as fetal grafts in functional repair of hippocampal damage, and that their preference for areas of cell loss and adoption of appropriate morphologies is consistent with a point-to-point repair mechanism.

Conditionally immortal neuroepithelial stem cell grafts reverse age-associated memory impairments in rats

In order to investigate the effects of stem cell grafts on water maze deficits in aged (22-month-old) rats, three groups of aged rats, assigned by pre-training latency scores to unimpaired, impaired control and impaired grafted groups, were compared with young (five-month-old) controls, six to eight weeks after implantation of cells from the conditionally immortal Maudsley hippocampal stem cell line, clone 36 (MHP36 stem cell line), in the cortex, striatum and hippocampus. Grafted rats were substantially superior to their matched impaired aged controls, and learned to find the platform as rapidly as unimpaired aged rats, although young controls were more efficient than all aged groups in several measures of spatial search during training. On the probe trial, however, aged rats with grafts showed significantly better recall of the precise position of the platform than any other group, including young controls, possibly indicating some perseveration. A further comparison found that groups of unimpaired and moderately impaired aged rats showed far less improvement from water maze pre-training to acquisition phases than young controls, indicative of progressive deficits over time. Histological investigation showed that beta-galactosidase-positive MHP36 cells migrated widely from the implantation sites to infiltrate the striatal matrix, all hippocampal fields and areas of the cortex. Grafted cells showed both astrocytic and neuronal morphologies, with cells of pyramidal and granular appearance in appropriate hippocampal strata.Taken together, these results indicate that neuroepithelial stem cell grafts extensively colonize the aged rat brain and substantially reverse progressive cognitive decline associated with ageing.

Cerebellar dentate nucleus in Alzheimer's disease with myoclonus

Although myoclonus commonly occurs in a later stage of Alzheimer's disease (AD), the pathological basis of this symptom is still unclear. In order to elucidate the neuropathological substrate of myoclonus in AD, we quantitatively assessed neuronal density and volume, with a discrimination between small and large neurons, at the rostral and caudal parts in the cerebellar dentate nucleus of 8 AD patients with myoclonus, 10 AD patients without myoclonus and 9 controls, using stereological probes. The neuronal numerical density of the large neurons at the rostral part and of total counts (rostral and caudal parts) in the myoclonic AD group were significantly greater than in the nonmyoclonic AD group. There were no significant differences in the density of small neurons between the two AD groups. The ratio of small neurons to large neurons (S/L ratio) of total counts was significantly lower in AD with myoclonus than in AD without myoclonus. The mean neuronal volume of the large neurons at the rostral part was significantly greater in myoclonic AD than in nonmyoclonic AD. Conversely, the volume of the small neurons at the rostral part was significantly lower in myoclonic AD than in nonmyoclonic AD. This study, for the first time, shows an increase in mean volume of large neurons and a decrease in mean volume of small neurons as well as a change in the S/L ratio in the dentate nucleus in AD with myoclonus. An imbalance in the S/L ratio as well as morphological changes of these neurons in the dentate nucleus may contribute to the pathological substrate of myoclonus in AD.

Recovery of spatial learning by grafts of a conditionally immortalized hippocampal neuroepithelial cell line into the ischaemia-lesioned hippocampus

Transient global cerebral ischaemia in rats causes relatively circumscribed and specific damage to the CA1 pyramidal cells of the dorsal hippocampus, along with a cognitive deficit manifest as difficulties in the performance of a range of spatial learning and memory tasks. Our previous studies have shown that restoration of behavioural performance in ischaemic rats by neural grafts taken relatively late in fetal development occurs only after local replacement of cells homotypic to those lost through the ischaemic insult. This lesion-plus-behaviour model therefore offers a powerful means for establishing whether multipotent embryonic neuroepithelial cells will engraft the damaged CA1, develop into appropriate neuronal phenotypes and produce behavioural recovery. Here we report that, in rats subjected to 15 min of global cerebral ischaemia, intrahippocampal implants of a conditionally immortal, multipotent cell line, directly derived from the embryonic day 14 hippocampal neuroepithelium of the H-2Kb-tsA58 transgenic mouse, selectively repopulated the lesioned CA1 pyramidal layer and restored ischaemia-induced deficits in acquisition of a hidden platform location in the Morris water maze.

Lewy bodies are located preferentially in limbic areas in diffuse Lewy body disease

Lewy bodies (LBs)are found throughout the brain stem, limbic and neocortical areas in Parkinson's disease. Lewy bodies are also associated in these areas with dementia and the substrate of 'dementia with Lewy bodies' is thought to include Lewy body pathology in limbic and neocortical areas with or without Alzheimer-type changes. In order to determine whether dementia with Lewy bodies is characterised primarily by cortical or limbic LB pathology, we have measured the density of Lewy bodies, neuritic plaques and neurofibrillary tangles in 12 neocortical, limbic and brain stem sites in 10 patients who were pathologically diagnosed with diffuse Lewy body disease (DLBD) (64.7 +/- 2.7 years). The mean LB density in limbic areas (3.00 +/- 0.61/mm2) was significantly greater than that of neocortical areas (1.13 +/- 0.22/mm2, P < 0.001). The greatest density of LBs was found in the amygdala (4.1 +/- 0.7/mm2) and the lowest in the occipital cortex (0.3 +/- 0.1/mm2). In limbic areas, LB formation positively correlated with neuritic plaque formation (r = 0.51, P < 0.01) but not with neurofibrillary tangle densities. These data indicate that dementia with Lewy bodies is characterised primarily by limbic, and secondly by neocortical, LB pathology. It remains to be determined why limbic areas are selectively vulnerable to LB pathology in dementia with Lewy bodies.

Influence of the presence of chicks on the ability to resume incubation behavior in domestic hens (Gallus domesticus)

In this study, hormonal and behavioral changes associated with nest deprivation in the absence or in the presence of chicks (replaced every day or not) were investigated in incubating hens. Prolactin levels decreased, whereas LH and E2 levels increased following nest deprivation. Surprisingly, the presence of chicks had no effect on prolactin changes. However, the presence of chicks significantly limited increases in plasma LH and estradiol. Furthermore, this inhibitory effect was greater when day-old chicks were replaced every day. On the other hand, the presence of chicks induced the emergence of specific maternal behavior, while, surprisingly, one-third of the nest-deprived hens without chicks continued to incubate. After a 3-day deprivation period, readiness to renest was maintained for a percentage of hens. Thus more than 2/3 of hens deprived of the nest for 3 days in the presence of chicks returned to their nests during the first day of being allowed to do so, versus less than 1/3 of hens without chicks among those that previously disrupted incubation behavior. Plasma prolactin concentrations of these renesting hens increased rapidly and reached again levels characteristic of incubating hens. We conclude that, under our experimental conditions, presence of chicks maintains readiness to incubate without maintaining high levels of plasma prolactin.

Respective effects of chicks and nest on behavior and hormonal concentrations of incubating domestic hens

Removal of incubating hens from their nestboxes or substitution of chicks for eggs disrupt incubation; prolactin levels decrease whereas luteinizing hormone and gonadal steroid concentrations tend to rise. The present experiment was undertaken to determine the relative influence of removing the nest (nest-deprived hens), adding chicks (maternal hens), or both (maternal nest-deprived hens), on the behavior and hormone concentrations of incubating hens. The results confirm that nest removal, as well as adding chicks, stops incubation. No differences were found between maternal and maternal nest-deprived hens' behavioral responses or hormonal concentrations. These results do not support the hypothesis that the drop of plasma prolactin observed in maternal hens is the consequence of the nest abandonment. In contrast, nest-deprived hens presented lower concentrations of prolactin and higher concentrations of estradiol than maternal and maternal nest-deprived hens. Moreover, the nest-deprived hens presented lower concentrations of prolactin and higher concentrations of LH and estradiol than the hens given chicks. We assume that physical contact with chicks, during brooding bouts, slows down the decrease of prolactin secretion and inhibits LH and estradiol release at the end of incubation.

Beta A4 protein deposition in familial Alzheimer's disease with the mutation in codon 717 of the beta A4 amyloid precursor protein gene and sporadic Alzheimer's disease

Beta A4 protein immunoreactivity in the neocortex and hippocampus of familial Alzheimer's disease (AD) including the case with the beta A4 amyloid precursor protein (APP) gene mutation in codon 717 (APP717 Val-->Ile) and sporadic cases of AD is described. A semi-automatic image analysis system was used to quantify beta A4 protein load in the isocortex of the frontal and temporal lobes and in subfields of the hippocampus. Immunoreactivity was measured in ten cases of sporadic AD and in five cases of familial AD including one in which the APP717 Val-->Ile mutation was present. Beta A4 protein load, as measured by square microns of immunoreactivity per square millimetre of cortex, was similar in the frontal and temporal isocortex in both sporadic and familial AD. There was greater variation in beta A4 protein load in subfields of the hippocampus but these differences were not significant between sporadic and familial cases. In the case with the APP717 Val-->Ile mutation. Beta A4 protein load in isocortex was greater than the mean for familial and sporadic cases of AD but less than the most severe cases of beta A4 protein deposition which were found in sporadic AD. In addition, the case with the APP717 Val-->Ile mutation has the same cytoskeletal pathology as sporadic cases of AD. The mechanism by which normal and mutant APP is processed to produce amyloidogenic fragments remains to be determined.

Astrocytosis, beta A4-protein deposition and paired helical filament formation in Alzheimer's disease

Alzheimer's disease (AD) temporal cortex (Brodmann area 22) was investigated using stains for astrocytes (GFAP immunohistochemistry), paired helical filaments (Gallyas silver impregnation) and beta A4-protein deposition (beta A4-protein immunohistochemistry). Paired helical filament formation (PHF), as demonstrated by neurofibrillary tangle (NFT) and neuritic plaque (NP) density, was greatest in the pyramidal cell layers III and V. beta A4-protein deposition was greatest in layer III but was present in all neocortical layers. In a regression analysis, astrocyte density was significantly correlated with beta A4-protein deposition (R2 = 0.35, P = 0.02). Astrocyte density was also positively correlated with PHF formation as measured by NFT (R2 = 0.16, P = 0.14) and NP (R2 = 0.25, P = 0.06) density, but this was less significant. This quantitative study demonstrates that both beta A4-protein deposits and PHF formation are positively correlated with the severity of astrocytosis and that damage to the brain parenchyma in temporal cortex in AD may be slightly more strongly associated with beta A4-protein deposition than paired helical filament formation. These results demonstrate the close association of astrocytes with beta A4-protein deposition and neuritic change in AD.

beta-Amyloid protein load is relatively uniform throughout neocortex and hippocampus in elderly Alzheimer's disease patients

beta-Amyloid protein immunoreactivity in neocortex and hippocampus of Alzheimer's disease and control brains has been measured using an automatic image analysis system. Successive fields from the pial surface to white matter in 4 neocortical sites, parahippocampal gyrus and along the pyramidal cell layer in the hippocampus have been measured using a number of variables including: area fraction or load, counts per unit area and deposit size. In Alzheimer's disease beta-amyloid protein load in neocortex and hippocampus was significantly greater than in non-demented age-matched controls. beta-Amyloid protein load, as measured by size variables, was relatively uniform throughout the neocortex in elderly Alzheimer's disease patients. However, greater variability in deposition was measured in parahippocampal gyrus and hippocampus than in neocortex. Size and density variables used to measure beta-amyloid protein deposition were not correlated with age although there was a tendency for the cortical load to decrease with age beyond 80 years.

Incubation and maternal behaviour in domestic hens: influence of the presence of chicks on circulating luteinising hormone, prolactin and oestradiol and on behaviour

1. The consequences of the adoption of chicks and their subsequent removal on behaviour and plasma hormone concentrations of incubating hens were investigated. Birds were divided into two group: in group A, incubating hens were given chicks for 11 d; in group B chicks were left with the hens for 3 d only. 2. Incubating hens given chicks immediately showed maternal responses. The introduction of chicks induced a gradual nest desertion. Their removal stopped nest desertion temporarily on day 4 in group B hens. 3. Plasma prolactin concentrations fell one day after introduction of chicks and continued to decline for about one week in group A hens, although there was no further significant decrease in group B hens. Circulating prolactin tended to decrease with time in both groups. 4. Plasma luteinising hormone (LH) concentrations increased concurrently with the decrease of prolactin. The increase was more abrupt in group B hens. 5. Plasma oestradiol concentrations decreased slightly on the day chicks were introduced. The decline was arrested by removal of chicks in group B; in group A the tendency was reversed about 10 days after chick introduction. 6. Irrespective of group, before chick removal hens which deserted their nest rapidly had less contact with chicks and lower prolactin concentrations.

Effect of estrogen on calcium homeostasis and pituitary hormones in the growing chick

An experiment was carried out to investigate the effect of a range of estradiol (E2) doses (0.1-6.5 micrograms/g body wt/day) on vitamin D metabolism and the plasma levels of growth hormone (GH) and prolactin (PRL) in the growing chick. Doses of 0.5-0.7 microgram/g E2, which are insufficient to raise the plasma calcium level, did induce an increase in growth rate, an increase in 25-hydroxyvitamin D 1 alpha-hydroxylase (1-hydroxylase) and 24-hydroxylase activities, and an increase in plasma GH level. These parameters leveled off or fell over the dose range 1-2 micrograms/g E2 but there was evidence of a second peak in 1-hydroxylase activity at 6 micrograms/g E2. At this high dose rate, the plasma Ca level rose to 8 mM, as it does in the laying hen; 24-hydroxylase activity, growth rate, and plasma GH and plasma PRL levels all decreased. It was concluded that the dose response to estrogen in the growing chick is not linear and, in the case of 1-hydroxylase activity, may even be biphasic.

Tendency to display spontaneous incubation does not affect maternal responsiveness in the domestic hen

Induction of maternal behavior was performed in 63-week-old hens of the JV15 (or "Vedette") strain which had previously exhibited brief incubating phases during the preceding egg-laying period to discover if their maternal behavior differed from that induced in hens who had no previous record of incubating. The degree of maternal behavior exhibited showed large variation among individuals. However, hens with a history of one or more spontaneous, brief incubation bouts and hens without such histories showed similar responsiveness toward chicks and similar levels of general activity. In most of the subjects, the establishment of maternal behavior was accompanied by a significant long-term fall in the plasma levels of luteinizing hormone whereas the plasma levels of prolactin appeared to be unaffected.

Induction of maternal behavior in incubating and non-incubating hens: influence of hormones

Maternal responses and variations in plasma levels of prolactin and testosterone have been studied in incubating and in non-incubating, non-laying hens during forced adoption experiments. The results demonstrate the ability of incubating hens to display complete maternal behavior as early as the 10th day of incubation after being exposed to stimulation by chicks during one night. Maternal responses also emerged in non-laying hens but more gradually. In both groups, a decline in plasma testosterone occurred after the introduction of the chicks and, in the incubating hens, prolactin levels fell as they abandoned their nests.

Plasma levels of arginine vasotocin, prolactin, aldosterone and corticosterone during prolonged dehydration in the domestic fowl: effect of dietary NaCl

Three groups of White Plymouth Rock laying hens were adapted to three levels of dietary NaCl: low-NaCl food with tap water (LOW), high-NaCl food (1% NaCl w/w added) with tap water (HT), and high-NaCl food with 0.5% NaCl for drinking (HS). The birds were subjected to water deprivation (dehydration) for 18 days. Blood sampling was done at 2-4 day intervals. Plasma concentrations of arginine vasotocin (AVT), prolactin (PRL), aldosterone (ALDO) and corticosterone (CS) were determined by radioimmunoassay. Plasma osmolality, sodium, chloride, and potassium were also determined. In the normally hydrated hens fully adapted to the diets, there was a stepwise increase from LOW to HS in plasma osmolality (305, 315, 332 mOsm, for LOW, HT and HS, respectively), [Na+] (144, 153, 161 mM) and [Cl-] (109, 119, 127 mM) as well as in [AVT] (6, 14, 18 pg/ml) and [PRL] (16, 24, 34 ng/ml). Regressing [AVT] on osmolality gave a slope of 0.30 pg . ml-1/mOsm and a threshold of 273 mOsm. The slope of [PRL] on osmolality was 0.73 ng . ml-1/mOsm. The correlation coefficient of [AVT] and [PRL] was 0.67. LOW had high [ALDO] (165 pg/ml) which was suppressed to low levels in HT and HS (5-8 pg/ml), while [CS] was the same in all groups (0.9-1.1 ng/ml). Plasma [K+] was decreased in the high-NaCl groups (5.8 mM in LOW, 4.4 and 4.7 mM in HT and HS). Dehydration resulted within 2 days generally in a sharp (5-15%) increase in osmolality, [Na+] and [Cl-], which thereafter increased more slowly during the remaining 16 days in all groups, with the slowest increase in LOW. The levels of osmolality [Na+] and [Cl-] were 5% lower in LOW than in HT and HS, which showed the same levels during the dehydration period. Plasma [AVT] and [PRL] increased 2-4 fold within 2 days of dehydration; [AVT] reached a plateau at 29 pg/ml in all groups, but [PRL] continued to rise in all groups, fastest in LOW, reaching similar levels in all groups after 14-18 days of dehydration, about 85 ng/ml. The correlation coefficient of [AVT] and [PRL] was decreased by half (to 0.32) during dehydration. Plasma [ALDO] increased in all groups with dehydration, 1.7 fold in LOW and 3-6 fold in HT and HS, but the levels reached in HT and HS were only 15-30% of that seen in LOW.(ABSTRACT TRUNCATED AT 400 WORDS)

Osmotic stimuli and NaCl-intake in the fowl; release of arginine vasotocin and prolactin

White Plymouth Rock hens were fed a high- and a low-NaCl content of the diet. The two groups were exposed to moderate dehydration, to intra-arterial hyperosmotic NaCl-loading, or to injection of physiological doses of arginine vasotocin (AVT). The plasma levels of AVT and prolactin were measured by accurate and sensitive radioimmunoassay and the osmolality and Na, K (and Cl) concentrations also measured for 48 h after dehydration, and for 60-90 min after NaCl-loading or AVT-injection. The plasma concentration of AVT after a given increase of plasma osmolality was in all experiments found higher in the low- as compared to the high-NaCl diet group. The average difference was 0.2 pg/ml X mOsm. The intra-arterial injection of AVT resulted in a strictly mono-exponential fall over the next hour with an average half-life of 6.3 min without any difference between the high- and the low-NaCl diet groups. It is concluded (a) that the release of prolactin after osmotic stimulation is most likely caused by a direct effect of osmolality (or Na concentration) and not by AVT, (b) that the release of AVT is influenced by the NaCl-intake in a direction which tends to maintain extracellular volume.

Mechanisms of release of prolactin from fowl anterior pituitary glands incubated in vitro: effects of calcium and cyclic adenosine monophosphate

Fowl anterior pituitary glands were bisected and each half was pretreated in either Medium 199 or medium containing EGTA to deplete endogenous calcium (Ca2+) stores, after which they were incubated in Medium 199, or Ca2+-free medium, containing prolactin release-stimulating agents and verapamil, a Ca2+ channel blocker. High K+ concentrations, hypothalamic extract, synthetic thyrotrophin-releasing hormone (TRH) and dibutyryl cyclic AMP (dbcAMP) all stimulated release of prolactin from control (non EGTA-treated) hemianterior pituitary glands. The effects of TRH and dbcAMP were not additive, but the response to submaximal concentrations of TRH was augmented by theophylline, a phosphodiesterase inhibitor. Reduction of Ca2+ availability with EGTA or verapamil reduced basal release of prolactin, prevented the prolactin-stimulating effects of high K+ concentrations and TRH, and markedly attenuated responses to hypothalamic extract and dbcAMP, EGTA being more effective than verapamil. Increasing the Ca2+ concentration of the medium did not augment basal or stimulated release of prolactin. These results suggest that both Ca2+ and cyclic AMP may act as intracellular mediators in the release of prolactin. Both basal and stimulated release of prolactin depend upon the presence of Ca2+. Although influx from the medium may be the major source of Ca2+, endogenous stores of Ca2+, perhaps mobilized by dbcAMP, may be able to maintain some release of prolactin. The prolactin-stimulating effects of TRH may be mediated by cyclic AMP.

The time sequence of adaptive changes to dietary phosphorus deficiency in the chick

Ten-day old chicks were divided into 6 groups which were fed a low phosphorus (P) diet for periods of 0, 0.5, 1, 3, 7 or 11 days before killing at 3 weeks old. Labelled calcium (47Ca) was injected intraperitoneally into some birds 18 hours before killing. A marked fall in growth rate, plasma phosphorus level, plasma growth hormone level and renal 24-hydroxylase activity levels had occurred by 12 hours after the experimental diet had started. After one day on the diet, the rate of duodenal Ca absorption had risen and continued to rise up to the 11th day. During this period, the renal 25-hydroxyvitamin D-1-hydroxylase activity rose slightly while the 24-hydroxylase activity rose towards the control level. At 24 hours, the 47Ca level in the bone was markedly lower than in the control group and remained low. It was concluded that the first adaptive response of the chick to dietary P insufficiency was to suppress growth. Subsequent adaptive responses were to increase the rate of Ca and P absorption from the gut and mobilisation from the bone but despite these measures, the growth rate only recovered slightly and the plasma P level continued to fall.

Age-related changes in prolactin and growth hormone release from pituitary glands in vitro

The basal release of prolactin from cockerel anterior pituitary glands in vitro declined between 1 and 7 weeks of age, to a level less than that released by pituitary glands from 18 week old (adult) cockerels and hens. Basal growth hormone (GH) release increased between 1 and 7 weeks of age but had declined in adults to a level similar to that released from 4 weeks old cockerels. The responsiveness of the pituitary gland to hypothalamic stimulation, using hypothalami from 8 week old broiler fowl, was also age-related. Prolactin release was considerably higher from pituitaries of 1 week old cockerels compared to the other age groups. Stimulation of GH release by the hypothalamus was higher from pituitaries of both 1 and 7 week old cockerels compared to the other groups of birds. The increase in release of prolactin following incubation with thyrotrophin releasing hormone (TRH) declined between 1 and 7 weeks, but increased slightly in adult birds, whereas the increase in release of GH following TRH was higher from pituitaries of both 1 and 7 week old cockerels. Hypothalamic prolactin (Prl) releasing activity, measured as the ability of the hypothalamus to stimulate hormone release from 8 week old broiler fowl anterior pituitary glands, declined with the age of the donor cockerels. The hypothalami from adult hens secreted significantly more Prl releasing activity than did adult cockerel hypothalami. The secretion of GH releasing activity decreased markedly with the age of the donor bird. These results suggest that maturational patterns of hormone secretion in fowl are partly due to changes in autonomous hormone release, to changing patterns of hypothalamic activity and to differences in pituitary responsiveness to provocative stimuli.

Effects of prostaglandin F2 alpha on prolactin secretion in the fowl

The plasma concentration of prolactin in immature cockerels was increased between 10 and 40 min after the intravenous administration of prostaglandin (PG) F2 alpha (200 micrograms/kg body weight). Lower doses had no effect on plasma prolactin concentration. The addition of PGF2 alpha (10(-9) to 10(-6) M) to incubation media had no effect on the basal release of pituitary prolactin but reduced the release of prolactin from pituitary-hypothalamus co-incubations. The addition of noradrenaline (10(-7) M), serotonin (10(-7) M), acetylcholine (10(-6) M) or histamine (10(-6) M) to the co-incubation increased the hypothalamus-induced prolactin release, although these effects were not observed in the presence of 10(-7) M PGF2 alpha. The in vitro release of pituitary prolactin was increased by adding chicken hypothalamic extract in the presence or absence of PGF2 alpha. These results suggest a dual effect on PGF2 alpha of prolactin secretion in the fowl; its stimulation in vivo may result from a peripheral action.

Circulating prolactin concentrations in chickens infected with Eimeria tenella

50000 oocysts of Eimeria tenella were inoculated into three-week-old cockerels and the effect of the infection (coccidiosis) on circulating concentrations of glucose, prolactin, sodium, potassium and haematocrit was determined. At day 5 of infection haematocrit was reduced and glucose was increased. From day 7 onwards prolactin concentration was elevated in infected birds compared with control and pair-fed birds. Plasma electrolytes were unchanged. It appears likely that loss of water resulting in osmotic changes during infection is the major reason for the observed changes in prolactin concentration in infected cockerels.

Effects of putative neurotransmitters on release of prolactin from pituitary glands of the domestic fowl co-incubated with hypothalamic tissue

Pituitary glands and hypothalami from broiler fowl heads were incubated alone or together with histamine, gamma-aminobutyric acid (GABA) or acetylcholine (ACh) as well as with catecholamines or neurotransmitter antagonists. Histamine and ACh stimulated, whereas GABA inhibited, the hypothalamus-induced release of prolactin, responses blocked by their specific antagonists. The dopamine antagonist pimozide, but not adrenergic (both alpha and beta), serotoninergic or cholinergic antagonists, prevented the actions of histamine and GABA. None of the antagonists except the cholinergic blocker, atropine, affected ACh-induced release of prolactin. Neither histamine nor ACh prevented inhibition of prolactin release by dopamine or stimulation of prolactin release by noradrenaline. GABA did not affect the response to noradrenaline. Furthermore, histamine, GABA and ACh had no effects on thyrotrophin releasing hormone-stimulated release of prolactin directly at the pituitary level. These results suggest that histamine and GABA affect prolactin release from chicken pituitaries in vivo by modifying the activity of the dopaminergic system. Acetylcholine may stimulate the secretion of prolactin releasing factor from the hypothalamus.

Stimulatory and inhibitory effects of prostaglandin E2 on prolactin release in the domestic fowl

In vivo prolactin secretion was increased in immature cockerels 20-30 min after the intravenous administration of prostaglandin (PG) E2 at a dose of 200 micrograms/kg. The addition of PGE2 to incubation medium had no direct effect on the release of pituitary prolactin during short-term (3-hr) culture, but augmented the stimulatory effect of hypothalamic tissue on prolactin secretion. The stimulatory effect of serotonin, noradrenaline, acetylcholine, and histamine on hypothalamus-induced prolactin release was also increased when pituitaries were coincubated with 10(-7)M PGE2, as was the stimulatory effect of thyrotrophin-releasing hormone (TRH) and hypothalamic extract (HE). The long-term (24-hr) preincubation of pituitaries with 10(-7)M PGE2 reduced the responsiveness of the prolactin-secreting cells to TRH or HE stimulation. PGE2 treatment also reduced the stimulatory effect of hypothalamic tissue on prolactin release and diminished the stimulatory effect of serotonin on hypothalamus-induced prolactin secretion. A 24-hr preincubation of hypothalamic tissue with 10(-7)M PGE2 also reduced its stimulatory effect on prolactin release when subsequently incubated with control pituitary glands. These results demonstrate that PGE2 initially stimulates in vivo and in vitro prolactin secretion in the fowl, possibly by increasing the release of hypothalamic prolactin-releasing activity and/or by increasing pituitary sensitivity to provocative stimuli. Chronic PGE2 stimulation appears to result in a reduction in pituitary responsiveness to stimulatory influences and in the release of hypothalamic-releasing activity.

Oestradiol 17 beta modifies fowl pituitary prolactin and growth hormone secretion in vitro

Chicken pituitary glands were incubated in medium containing oestradiol 17 beta (E2), alone or together with single whole hypothalami. E2 stimulated prolactin release from the pituitary and increased the prolactin releasing activity of the hypothalamus, but did not affect growth hormone release. Preincubation of pituitaries with E2 dramatically stimulated subsequent prolactin release. Pituitaries primed with E2 were more responsive to the prolactin-stimulating effects of hypothalamic extract (HE) and thyrotrophin-releasing hormone (TRH) and more sensitive to the prolactin-inhibiting effect of dopamine. E2-primed pituitaries were much less sensitive to the growth hormone releasing activity of TRH and HE. These results show that E2 may regulate pituitary function by direct effects on hormone release by modifying pituitary sensitivity to stimulatory or inhibitory influences and by altering hypothalamic releasing activity.

Progesterone inhibits prolactin and growth hormone release from fowl pituitary glands in vitro

After preincubation of anterior pituitary glands of broiler fowls for 20 h in either medium alone or medium containing progesterone, their responsiveness to hypothalamic stimulation and to thyrotrophin releasing hormone (TRH) was determined. Following exposure to progesterone the basal rate of release of prolactin was reduced in a concentration-related manner but basal growth hormone release was unaffected. Stimulation of the release of prolactin and growth hormone by both hypothalamic extract and TRH was reduced following incubation with progesterone, and the reduction of the prolactin response to TRH was related to progesterone concentration.

Dopaminergic inhibition of prolactin release from pituitary glands of the domestic fowl incubated in vitro

Anterior pituitary glands from broiler fowl were incubated by themselves, with hypothalamic tissue or with thyrotrophin releasing hormone (TRH) in medium containing dopamine and its antagonist pimozide. The presence of hypothalamic tissue or TRH resulted in a stimulation of release of prolactin. Neither dopamine nor pimozide affected prolactin release directly from the pituitary gland. Dopamine inhibited the release of prolactin stimulated by hypothalamic tissue or TRH, in a concentration-dependent fashion. Pimozide diminished the response to dopamine. After pituitary glands were preincubated for 20 h in medium containing oestradiol-17 beta, the basal release of prolactin was enhanced as was the response to TRH. Both basal and TRH-stimulated release of prolactin from the oestrogen-primed pituitary glands was inhibited by dopamine, an effect blocked by pimozide. Hypothalami from broiler fowl were incubated for up to 8 h in medium containing dopaminergic drugs and pituitary glands were incubated in this medium, alone or with pimozide. As indicated by the prolactin released by the pituitary glands, the hypothalami appeared to secrete prolactin-releasing activity in a time-related fashion. Dopaminergic activity was also present in the hypothalami, since pimozide enhanced the prolactin-releasing activity of the medium. Dopamine apparently inhibited and pimozide stimulated the secretion of releasing activity from the hypothalamus. These results suggest that dopamine inhibits release of prolactin directly from the pituitary gland only when prolactin secretion is high. The hypothalamus secretes at least two factors regulating prolactin secretion, a prolactin-releasing factor and a dopaminergic prolactin-inhibiting factor. Dopamine may also play an inhibitory role in the regulation of secretion of the prolactin-releasing factor.