Prostaglandin E2-induced fever in young and old Long-Evans rats.

Aging is associated with a blunted or absent fever response to naturally occurring infections or to the peripheral administration of bacterial products and proinflammatory cytokines. We have recently shown that old Long-Evans rats are not defective in their capacity to develop a fever in response to brain administration of interleukin-1beta (IL-1beta). Here, we investigated the fever response of young (3-5-month) and old (24-26-month) Long-Evans rats to the intracerebroventricular (i.c.v.) microinfusion of prostaglandin E2 (PGE2), a final common mediator for the production of fever in the brain. Core body temperature was monitored by telemetry in freely moving rats. i.c.v. administered PGE2 (100 ng) induced comparable increases in body temperature in young and old Long-Evans rats. In the two groups, PGE2-induced fever was similar both in latency-to-peak fever and maximal fever response. These data, and the previous data on IL-1beta, demonstrate that the brains of old and young rats are similar with respect to fever generation in response to the i.c.v. administration of two classes of immunomodulators.     

In-vitro effects of bromocriptine on isolated pituitary adenoma cells. Ultrastructural and morphometrical studies

3 pituitary adenomas in hyperprolactinemia and 3 GH and prolactin producing tumours were analysed. The adenoma cells were prepared and held in suspension so that they could be treated with bromocriptine (10 ng and 100 ng). At different times after treatment (0.5, 60 and 90 minutes), the cells were fixed and prepared for conventional electronmicroscopy. Electron microscopic photographs were quantitatively analysed by the point counting method. The results were compared to those of an untreated control group. After bromocriptine influence, there was a decrease of the hormone secretion into the supernatant (2 of 3 prolactin producing adenomas). The prolactin secretion was unchanged in all 3 adenomas which produced prolactin and GH, but there was a decrease in the GH production in 1 of these cases. Ultrastructural morphometry revealed the following results: In prolactin producing adenomas, there was a decrease in the number of exocytoses, an increase in the volume density of lysosomes (2 cases) and an increase of the rough endoplasmic reticulum (1 case). The decrease of the "unorganized" cytoplasm was observed in all 3 cases, but was significant only in 1 case. There was a significant increase in secretory granules (1 case). In adenomas which produced prolactin and GH displayed a significant increase of the rough endoplasmic reticulum and of the granules. The outlines of the cellular membranes seemed smoother (1 case). The heterogeneous results may be interpreted as an expression of the reduced hormone secretion (secretory granules, lysosomes), some data are in accordance with the beginning of necrobiotic phenomena (rough endoplasmic reticulum). The decrease of the "unorganized" cytoplasm may be due to a shrinking process.     

An immunocytochemical study of pituitary adenomas and focal hyperplasia in old Sprague-Dawley and Fischer 344 rats

Spontaneous pituitary tumors occurring in groups of 100 Sprague-Dawley (SD) and 100 Fischer 344 (F344) rats of each sex on a 2-year aging study were characterized by immunocytochemistry. The SD strain had a total of 75 tumors with 10% in males and 65% in females. Tumors immunoreactive for prolactin (PRL) alone were the most common tumor (64%) with the immunonegative tumor being the second most common (17.3%). F344 rats had a total of 62 tumors with 26% in males and 36% in females. The majority of the tumors were reactive for prolactin alone (56.5%) and tumors reactive for both growth hormone (GH) and PRL were the second most common (21%). Most tumors were immunoreactive for only 1 hormone; however, both strains had tumors that expressed multiple hormones in unusual combinations.     

Glomerular lesions in spontaneously occurring diabetic WBN/Kob rats

Glomerular lesions in WBN/Kob male rats with spontaneous diabetes were examined histopathologically. The glomerulopathy caused by diabetes was compared with lesions in chronic progressive nephropathy of non-diabetic SD and F344 male aged rats. Diffuse and global thickening of the mesangial area was observed only in WBN/Kob rats and showed a statistically significant correlation with serum glucose concentrations. Therefore, it suggested that the mesangial thickening was a result of hyperglycaemia. Fibrin cap-like lesions were seen in both WBN/Kob and non-diabetic SD or F344 male rats. The severity of these lesions was closely related to that of chronic progressive nephropathy and, therefore, the fibrin cap-like lesions were considered to be due to the chronic progressive nephropathy.     

Therapeutic effects of tetrathiomolybdate on hepatic dysfunction occurring naturally in Long-Evans Cinnamon (LEC) rats: a bona fide animal model for Wilson's disease.

Long-Evans Cinnamon (LEC) rats were fed a diet containing 7 ppm Cu and 30 ppm Cu from 60 days after birth. Fischer (Fischer group) and LEC (LEC-control group) rats fed a 7 ppm Cu diet showed normal growth throughout the whole period (60 to 125 days after birth). On the other hand, LEC rats fed the 30 ppm Cu diet had decreased body weight and showed slight jaundice at around 100 days after birth. Tetrathiomolybdate (TTM, 10 mg/kg bw) was injected sub-cutaneously at 101 and 105 days after birth into half of the LEC rats fed the 30 ppm Cu diet. LEC rats given TTM (LEC+TTM group) recovered their body weight and the jaundice rapidly disappeared. However, LEC rats without TTM (LEC-TTM group) had sharply decreased body weight and showed severe jaundice at 103 days after birth. The hepatic Cu concentration in LEC+TTM rats (460 micrograms/g) exceeded that of LEC-control rats (330 micrograms/g) at 125 days after birth. Our data suggest that TTM is effective for treatment of acute hepatic injury in the LEC rat.     

Effects of pergolide on diethylstilbestrol-induced rat pituitary hyperplasia.

Hyperplastic anterior pituitary glands were produced in female rats by treatment with 10 mg of diethylstilbestrol in Silastic tubing. This led to increased numbers of immunoreactive prolactin cells and increased serum prolactin levels. After 6 weeks of diethylstilbestrol treatment, one group of rats was treated with daily injections of pergolide for 3 weeks. Pergolide produced a significant decrease in pituitary gland weight and in serum prolactin levels but did not change the percentage of prolactin cells significantly, compared with that of control rats. Ultrastructural studies showed a significant increase in the numbers of prolactin secretory granules and numerous large intracellular bodies with associated secretory granules in pituitaries from rats treated with pergolide. In one group of rats in which the diethylstilbestrol was discontinued for 3 weeks after 6 weeks of treatment there was a significant decrease in pituitary gland weight and serum prolactin and a significant decrease in the percentage of prolactin cells, compared with values in the rats treated with diethylstilbestrol for 9 weeks. These results indicate that pergolide causes decreased release of prolactin from secretory granules in anterior pituitary prolactin cells and an increase in the numbers of PRL secretory granules per cell but does not change the percentage of prolactin-producing pituitary cells after 3 weeks of treatment.     

Comparative effects of hydralazine and captopril on the cardiovascular changes in spontaneously hypertensive rats.

Vascular changes that develop during the course of blood pressure rise in spontaneously hypertensive rats (SHRs) can be modified by antihypertensive therapy. It is not known, however, whether there is selectivity in the structural response to specific antihypertensive drugs. This issue was examined by comparing the effects of a direct vasodilator (hydralazine) and a converting enzyme inhibitor (captopril) on morphologic aspects of the cardiovascular system. Male SHRs, 21 weeks of age, were given either hydralazine (HCl plus hydrochlorothiazide, captopril plus hydrochlorothiazide, or hydrochlorothiazide alone. Untreated age-matched SHRs and Wistar-Kyoto normotensive rats (WKYs) were used as controls. Animals were sacrificed at 27-28 weeks of age. Both hydralazine and captopril lowered significantly the blood pressure of SHRs, whereas hydrochlorothiazide alone was ineffective. The heart/body weight ratios were dramatically reduced in captopril-treated SHRs to below the level of WKYs; hydralazine induced only a very modest (5%) reduction, whereas the diuretic alone was ineffective. The morphology of the aortic intima improved dramatically in response to captopril and hydralazine and, to a lesser extent, hydrochlorothiazide alone. This effect becomes apparent within 6 weeks of treatment, and the only evidence of preexisting disease is the persistence of collagen in the subendothelium. Captopril and hydralazine, but not hydrochlorothiazide alone, reduce the thickness of the aortic media below that of normotensive controls. In addition, captopril and hydralazine improve the structure of small intrarenal vessels. There was a strong correlation between the relative effectiveness of the three pharmacologic agents in lowering blood pressure and in improving the changes of intrarenal vessels. These results highlight the capacity of antihypertensive therapy to arrest or reverse the structural sequelae of hypertension. In addition, they underscore the heterogeneity in the response of different components of the cardiovascular system, which, in part, reflects selectivity in the action of antihypertensive agents.     

Transplantation of pituitary and adrenal glands of spontaneously hypertensive rats into hypophysectomized or adrenalectomized,normotensive Sprague-Dawley rats.

Pituitary and adrenal glands removed from male and female spontaneously hypertensive (SH) rat donors with high blood pressure were implanted in normotensive, Sprague-Dawley (S-D) recipients which had been hypophysectomized or adrenalectomized. The transplants were accepted readily and after 90 days the animals were necropsied. Maintenance of organs and body weights suggested that the pituitary glands of SH rats have an adequate content of growth hormone but there may be an intrinsic deficiency of gonadotrophic hormones in this strain. The blood pressure of the hypophysectomized and adrenalectomized recipients was well maintained, particularly by the Sh-rat adrenal transplants, but the blood pressure of the recipients did not become abnormally elevated. SH-rat pituitary and adrenal glands caused fatty infiltration of the liver and hyperlipidaemia indicative of a lipotrophic factor in the SH rat strain. The histopathological changes in the transplanted pituitary and adrenal glands, and in intact pituitary and adrenal glands of the recipients, suggested that SH-rat pituitary glands secrete extra quantities of ACTH, that the pituitary-adrenal axis of this strain is extra sensitive to stressful stimuli, and that the spectrum of adrenal steroids secreted by this strain may be different from that of most normotensive strains.     

Bacterial flora in spontaneously occurring aural cholesteatomas in Mongolian gerbils.

Bacteria were isolated from 29 Mongolian gerbils, Meriones unguiculatus, with spontaneous aural cholesteatomas. We identified 148 cultures, 44 from the middle ear surface of cholesteatomas and 104 from cholesteatoma contents. We could only identify 63 cultures to the genus level, although we identified 85 cultures as belonging to 21 different species. We found on the surfaces of cholesteatomas representatives of 9 genera, from which 8 species could be identified, and representatives of 19 genera within the cholesteatoma sac, from which 21 species could be identified. The most common bacterial genera isolated were Staphylococcus, Pseudomonas, and Corynebacterium among the aerobic genera, and Bacteroides and Peptococcus among the anaerobic genera. The bacterial flora of gerbilline cholesteatomas was found to be diverse, resembling the flora found to be associated with human cholesteatomas. The flora also resembled the organisms found transitorily within the normal middle ear cavity of gerbils, except for a higher incidence of pseudomonads.     

Further characterisation of a spontaneously occurring antibasement membrane antibody.

A spontaneously occurring antibasement membrane antibody has been further characterised according to antigenic specificity, immunoglobulin class, and tissue localisation using immunofluorescent and immunoelectron microscopic techniques. The autoantibody reacted with the basement membrane of kidney tubules, Bowman's capsule, and the epithelial portion of ileum but not with the basement membrane of skin, cornea, glomerulus, or oesophagus. It also reacted with bile canaliculi, sarcolemmal sheath, and salivary duct. On electron microscopy the antibody was distributed along the basement membrane of Bowman's capsule and renal tubules. Some reactivity against collagen was observed. Antibody activity was found in both IgG and IgM fractions. In immunodeficiency disorders, the autoantibody was found only in patients with selective IgA deficiency.     

The effects of heparin treatment on hypertension and vascular lesions in stroke-prone spontaneously hypertensive rats.

Stroke-prone spontaneously hypertensive rats (SPSHRs) were used to test the theory that heparin treatment may prevent the development of "malignant" hypertension and fibrinoid vascular lesions in the kidney. Subcutaneous injections of heparin (100 units/100 g body weight) were given every 8 hours over a 5-week period to 12 young (10-week-old) SPSHRs. A control group of 12 SPSHRs was injected with saline. Both heparin-treated and control animals showed an incremental rise in mean systolic pressure, but the pressure was significantly lower (P less than 0.05) in the heparin-treated animals during weeks 1-4 of treatment. There were significantly fewer fibrinoid vascular lesions (P less than 0.03) in the heparin-treated group. In 7 additional heparin-treated and 7 control SPSHRs plasma and blood volumes were determined for assessment of the effects of heparin treatment. There was no significant difference in total blood volume or plasma volume between the two groups, but heparin-treated animals had lower hematocrit levels. In 8 SPSHRs direct arterial pressures were recorded for 1 hour after a single heparin injection, and no acute changes in blood pressure were observed. The results suggest that heparin treatment prevents the development of severe fibrinoid vascular lesions and also attenuates the rate of the rise in systolic blood pressure; moreover, this reduction in blood pressure is not caused by a significant reduction in blood volume or an acute hypotensive effect of heparin.     

Pars intermedia of the human pituitary revisited: Morphologic aspects and frequency of hyperplasia of POMC-peptide immunoreactive cells

The human pituitary has no distinct pars intermedia (PI). Instead, the proopiomelanocortin (POMC) producing, adrenocorticotropin (ACTH)- and β-endorphin-immunoreactive PI cells are incorporated within the pars anterior, thereby participating in the formation of the pars distalis. Two hundred fifty autopsy pituitaries (156 males, 94 females) have been studied by histology and immunohistochemistry to determine the frequency of clinically non-functioning ACTH- and β-endorphin immunoreactive (POMC) cell hyperplasia/adenoma probably attributable to PI-derived cells. Such hyperplasia occurred in 29% of men and 14% of women; 80% of the male and 77% of the female subjects were over 50 yr of age. In two of the women, POMC cell adenoma was present as well. Except for hypothyroidism, none of the cases with POMC cell hyperplasia had endocrine disorder. No obvious correlation was evident between POMC cell hyperplasia/adenoma and clinical presentation. Hyperplasia of PI-derived POMC cells may be suspected by virtue of differential intraglandular localization of these cells. Except for cases of glucocorticoid treatment, leading to Crooke’s hyalinization of ACTH cells, but not affecting PI cells, no conclusive separation of various POMC-producing subsets is possible at present. The PI-derived cells probably give rise to silent “corticotroph” adenoma subtype 1 and subtype 2.     

Glycogen accumulation in the renal tubular cells of spontaneously occurring diabetic WBN/Kob rats

Cytoplasmic and nuclear accumulation of glycogen granules in the kidney cells of 72 male WBN/Kob rats with a long-term diabetic condition was studied histologically and by electron microscopy. The incidence and degree of the accumulation showed good correlation with the blood glucose concentration. In the kidneys, there was evidence of two types of lesion, cytoplasmic glycogen accumulation in the distal convoluted tubules and nuclear accumulation in the ascending thick segment of Henle's loops. Electron microscopically, the cytoplasmic glycogen accumulation was often associated with an increased number of lysosomal bodies containing lamellar bodies. Glycogen bodies, the halo of which was thought to be identical with that of nuclear bodies, were frequently observed in the nuclei containing the glycogen granules. These morphological and topographical differences between the two types of lesion were considered suggestive of different pathogenetic mechanisms for glycogen accumulation in the kidney cells.     

In vitro pituitary responsiveness to LHRH in young and old female rats. Influence of melatonin

The effect of aging and melatonin on in vitro pituitary responsiveness to luteinizing hormone-releasing hormone (LHRH) was studied. Young cyclic (3-months-old) control (cyclic-control, N = 15), and melatonin (MEL) treated for 2 months (150 microg/100 g BW) (cyclic-MEL, N = 15), old acyclic (23-months-old) control (acyclic-control, N = 13), and MEL-treated (acyclic-MEL, N = 18) rats were used. The hormones analyzed were luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL). The results showed a different influence of the reproductive status as well as of melatonin on the basal secretion rate of both gonadotropins, i.e. LH and FSH. Only the basal FSH release was significantly reduced in cyclic-MEL and acyclic-controls compared to cyclic-controls. The hemipitutary FSH content raised to values similar to those observed for FSH secretion and only the cyclic-MEL group showed significantly higher FSH pituitary content than for release. LHRH addition to the incubation medium resulted in increased LH release for both cyclic and acyclic rats, but FSH release was only stimulated in acyclic rats. Melatonin treatment blunted this response in both cases. In addition, melatonin treatment inhibited prolactin release in acyclic-MEL group after LHRH stimulation but not the basal levels. Pituitary LH and prolactin contents, were significantly higher than the pituitary LH and prolactin levels released from all groups studied, and were not affected by reproductive senescence nor by exogenous melatonin. These data indicate that aging influences more the secretory than the biosynthetic processes. Melatonin influences is endocrine status-dependent, being inhibitory when pituitary hormones reach their higher values.