Acyltransferases and transacylases involved in fatty acid remodeling of phospholipids and metabolism of bioactive lipids in mammalian cells

Over 100 different phospholipid molecular species are known to be present in mammalian cells and tissues. Fatty acid remodeling systems for phospholipids including acyl-CoA: lysophospholipid acyltransferases, CoA-dependent and CoA-independent transacylation systems and lysophospholipase/transacylase are involved in the biosynthesis of these molecular species. Acyl-CoA:1-acyl-2-lysophospholipid acyltransferase prefers polyunsaturated fatty acyl-CoAs as acyl donors while acyl-CoA:2-acyl-1-lysophospholipid acyltransferase prefers saturated fatty acyl-CoAs. Therefore, the acyl-CoA:lysophospholipid acyltransferase system is involved in the synthesis of the phospholipid molecular species containing sn-1 saturated and sn-2 unsaturated fatty acids. The CoA-dependent transacylation system catalyzes the transfer of fatty acids esterified in phospholipids to lysophospholipids in the presence of CoA without the generation of free fatty acids. The CoA-dependent transacylation reaction in rat liver exhibits strict fatty acid specificity, i.e., three types of fatty acids (20:4, 18:2, and 18:0) are transferred. On the other hand, the CoA-independent transacylase catalyzes the transfer of C20 and C22 polyunsaturated fatty acids from diacyl phospholipids to various lysophospholipids, in particular, ether-containing lysophospholipids, in the absence of any cofactors. The CoA-independent transacylase is assumed to be involved in the accumulation of polyunsaturated fatty acids in ether-containing phospholipids and in the removal of deleterious ether-containing lysophospholipids. These acyltransferases and transacylases are involved in not only the remodeling of fatty acids but also the synthesis and degradation of some bioactive lipids and their precursors. In this review, the properties of these fatty acid remodeling systems and their possible roles in the biosynthesis of bioactive lipids are described.

[Three dimensional (3D-) clinostat and its operational characteristics]

Three dimensional clinostat has been developed for simulation of microgravity on ground. It has applied in many disciplines in gravitational biology. Outline of operational principle is described together with its mechanical design. Rotation around two independent axes makes direction of gravity vector to scan whole steric angle. Magnitude and direction of rotational angular velocity is selected randomly at a certain interval of time to avoid singularity in sweep trajectory of gravity vector. Methods for validation of the operation are presented to test randomness of motion and cancellation of gravity by clino-rotation. Concerns discussed are vibration originated in motor and pseudo-weak magnetic field generated on clinostat. Fluid flow induced by clino-rotation is pointed as another problem to be taken into account.

[Minimally invasive direct coronary artery bypass grafting (MIDCAB) without cardiopulmonary bypass: a case report]

A new coronary artery bypass grafting of the left anterior descending coronary arteries (LAD) with in situ internal thoracic artery (ITA) bypass grafts through a limited anterior thoracotomy was performed in a 70-year-old [correction of 60] patient. The left ITA-LAD anastomosis was completed without cardiopulmonary bypass and postoperative angiography showed a patent anastomosis. With this minimally invasive approach, the procedure should provide the benefits of ITA grafting with rapid recovery short hospital stay without complication associated with cardiopulmonary bypass in selected cases.

Inhibition by 2-arachidonoylglycerol, a novel type of possible neuromodulator, of the depolarization-induced increase in intracellular free calcium in neuroblastoma x glioma hybrid NG108-15 cells

2-Arachidonoylglycerol was found to inhibit the depolarization-induced increase in [Ca2+]i in NG108-15 cells differentiated with prostaglandin E1 and theophylline in a dose-dependent manner. Such an effect appears to be rather specific to polyunsaturated fatty acid-containing monoacylglycerols such as 2-arachidonoylglycerol. Neither 2-palmitoylglycerol nor free arachidonic acid exhibited appreciable inhibitory activity. These observations raise the possibility that 2-arachidonoylglycerol attenuates the increase in [Ca2+]i, thereby modulating several neural functions in this type of cell.

Somatostatin and brain-derived neurotrophic factor mRNA expression in the primate brain: decreased levels of mRNAs during aging

The expression of the genes for somatostatin (SRIF) and brain-derived neurotrophic factor (BDNF) was investigated in the central nervous system (CNS) of the macaque monkey (Macaca fuscata fuscata). Using Northern blot analysis, one SRIF mRNA transcript, 0.65 kb, and two BDNF mRNA transcripts, 1.6 and 4.0 kb in length, were detected in the monkey brain tissues. During the aging process (2 years, 10 years, and > 30 years), the ratio of SRIF mRNA/glyceraldehyde-3 phosphate dehydrogenase (G3PDH) mRNA significantly decreased (60-70%) in the hippocampus and in several cerebral subdivisions such as frontal cortex, temporal cortex, motor cortex, somatosensory cortex and visual cortex. BDNF mRNA was expressed in the various cerebral subdivisions and in the hippocampus. During the aging process, the gene expression of BDNF declined (20-50% for the 4.0 kb transcript, and 40-70% for the 1.6 kb transcript) in the various cerebral subdivisions. In the hippocampus, the level of the 1.6 kb mRNA at > 30 years old declined to 60% of the level at 2 years old, while the 4.0 kb mRNA did not change significantly during the aging process. Recent studies have shown that BDNF enhances the expression of SRIF mRNA in the rodent cerebral cortex (Nawa, H. et al., J. Neurochem., 60 (1993) 772-775; Nawa, H. et al., J. Neurosci., 14 (1994) 3751-3765). These studies and our present results suggest that the decrease in gene expression for a neurotrophic molecule, such as BDNF, might cause the levels of SRIF mRNA to decline in the primate brain during the aging process.

Inhibition of UDP-glucuronosyltransferase activity by fatty acyl-CoA. Kinetic studies and structure-activity relationship

We previously identified and purified UDP-glucuronosyltransferase (UGT) isoforms as targets of protein acylation from rat liver microsomes (Yamashita et al., Biochem J 312: 301-308, 1995). The acylation of UGT isoforms occurred upon incubation with acyl-CoA without another protein acyltransferase, suggesting that it was autoacylation. The study revealed the interaction of UGT isoforms with acyl-CoA. In the present study, the effects of fatty acyl-CoA on UGT activities were examined thoroughly, using a rat liver microsomal and purified enzyme fractions. The UGT activities of both fractions were inhibited by acyl-CoA in a concentration-dependent manner. The effect of acyl-CoA was observed on the activities toward various substrates, suggesting that the effect shows the wide spectrum of the isoforms of UGT. To assess the mechanism underlying the inhibition of UGT activity by acyl-CoA, the relationship of the inhibition, acyl-CoA binding to the proteins, and changes in the tertiary structure of the enzyme were examined. The kinetics of these phenomena were related closely with each other. Furthermore, the inhibition of UGT activity was specified for acyl-CoA, though a structurally related compound, acyl-3-dephosphoCoA, had no inhibitory effect. The results suggested that the specific binding of acyl-CoA to UGT isoforms induced conformational changes of the enzymes and resultant inhibition of UGT activity.

Microtubule-associated coiled-coil protein Ssm4 is involved in the meiotic development in fission yeast

BACKGROUND

In fission yeast, an RNA species named meiRNA is specifically required for the promotion of the first meiotic division. To dissect the function of this RNA and its partner RNA-binding protein Mei2, we screened for high-copy-number suppressors of the arrest prior to the first meiotic division caused by loss of meiRNA.

RESULTS

Analysis of one of the suppressors, named ssm4, suggested that it encodes a coiled-coil protein carrying a microtubule-binding motif at its N-terminus. Expression of ssm4 was restricted to cells undergoing meiosis. Disruption of ssm4 affected neither vegetative growth nor conjugation, but resulted in frequent generation of asci carrying less than four spores. Tagged Ssm4 could colocalize with microtubules in mitotic cells, and was seen to localize at spindles during both the first and the second meiotic division. The microtubule-binding motif was essential for the association of Ssm4 with microtubules and for its function during meiosis, but not for the suppression of loss of meiRNA. Ssm4 appeared to possess a potential to migrate to the nucleus.

CONCLUSIONS

Ssm4 is a microtubule-colocalizing protein that plays a role specifically in meiosis. Ssm4 appears to modify the structure or the function of nuclear microtubules in order to promote the meiotic nuclear division.

The mechanism of action of KBT-3022, a new antiplatelet agent

1. The mechanism of action of a new antiplatelet agent, KBT-3022 (ethyl 2-[4,5-bis(4-methoxyphenyl)thiazol-2-yl]pyrrol-1-ylacetate) and its active main metabolite, desethyl KBT-3022, was investigated. 2. KBT-3022 and desethyl KBT-3022 inhibited cyclooxygenase from ovine seminal gland with IC50 values of 0.69 and 0.43 microM, respectively. 3. At concentrations higher than those required for cyclooxygenase inhibition, desethyl KBT-3022 inhibited cAMP-phosphodiesterase, specific binding of U46619, and release of phosphatidic acid from thrombin-stimulated platelets. 4. Oral administration of KBT-3022 inhibited the production of thromboxane B2 during blood coagulation more potently than the production of 6-keto-prostaglandin F1 alpha from aortic strips in guinea pigs. 5. These findings suggest that KBT-3022 may inhibit platelet activation principally via the inhibition of cyclooxygenase by desethyl KBT-3022.

Stereologically estimated mean nuclear volume of prostatic cancer is a reliable prognostic parameter

Although different histological grading systems of prostatic cancer refer to well-described characteristics, results are hard to reproduce. The aim of this study was to obtain morphometric data that would enable objective and reproducible grading of prostatic cancers by stereological estimation of mean nuclear volume (MNV). The clinical records and tissue specimens from 100 patients who were newly diagnosed as having prostatic cancer from 1973 to 1990 and who were followed up for 5 years or longer were retrospectively examined. We analysed the relationship between MNV and clinical stage, Gleason score and histological grading according to the World Health Organization (WHO) classification. To evaluate prognostic predictors, a multivariate analysis of factors associated with cause-specific survival was performed. We found a good correlation between the MNV and clinical stage and between the MNV and histological grading. There was no correlation between MNVs and Gleason scores. Multivariate analysis revealed that the MNV was the only predictor of survival time (coefficient 0.005; P < 0.0001; hazard ratio 1.005). We consider that the MNV is an excellent predictor of the prognosis in patients with prostatic cancer. Moreover, stereological estimation of MNV is a simple, quick, inexpensive and reliable morphometric procedure that enables the quantitative analysis of the histological and biological character of prostatic cancer.

2-Arachidonoylglycerol, a putative endogenous cannabinoid receptor ligand, induces rapid, transient elevation of intracellular free Ca2+ in neuroblastoma x glioma hybrid NG108-15 cells

Low concentrations of 2-arachidonoylglycerol were found to induce rapid, transient elevation of intracellular free Ca2+ in NG108-15 cells (EC50 was 150 nM). Free arachidonic acid, 2-palmitoylglycerol, 2-oleoylglycerol, 2-linoleoylglycerol and 2-docosahexaenoylglycerol were inactive. Anandamide acted as a partial agonist. Importantly, desensitization was observed upon sequential challenge with 2-arachidonoylglycerol. Furthermore, cross-desensitization was observed between 2-arachidonoylglycerol and WIN 55212-2, a cannabinoid receptor agonist. Pretreatment of the cells with SR141716A, a cannabinoid receptor antagonist, abolished the activities of both 2-arachidonoylglycerol and WIN 55212-2. These results strongly suggest that 2-arachidonoylglycerol and WIN 55212-2 bind to a common cannabinoid receptor to elicit cellular responses and that 2-arachidonoylglycerol has some physiological role in nervous tissues.

[The changes in lymphocytes subpopulations of a patient with postoperative chylothorax]

A case of 64-year-old male who developed chylorrhea at 2 days post coronary artery by-pass grafting, is reported. He was managed conservatively for 3 weeks. But chylothorax was not improved, he was treated operatively. Analysis of his lymphocyte subpopulations in peripheral blood were performed during the course of chylothorax. Lymphocytepenia became apparent and subpopulation of T cell were decreased gradually. The subpopulation of CD 4(+) cell decreased, while the subpopulation of CD 8(+) increased. The CD 4(+) cell/CD 8(+) cell ratio decreased consequently till 7th day after 2nd operation. Although the replenishment of nutritional deficiencies using TPN allows prolonged conservative management for chylothorax patient, the deterioration in cellular immunocompetence can not be prevented at present. It is necessary to take great care about infection for chylothorax patient.

Effects of sustained unilateral molar clenching on the temporomandibular joint space

OBJECTIVE

To measure the effect of unilateral sustained clenching on the temporomandibular joints, changes in the minimum joint space dimension were assessed.

STUDY DESIGN

Ten healthy subjects performed a sustained clench on a bite force transducer in the first molar region for 5 minutes with a constant force of 170 N. Three separate sagittal tomograms were bilaterally obtained with the transducer in place before clenching and during the beginning and at the end of the contraction. Changes were quantified with a computerized image analysis system.

RESULTS

The minimum joint space of the contralateral temporomandibular joint was significantly reduced both at the beginning and at the end of the contraction task. Further the minimum joint space was also significantly less at the end than at the beginning of the contraction even though bite force level was identical. The ipsilateral condyle images showed no significant shift in the minimum joint space.

CONCLUSIONS

These data suggest that unilateral molar clenching induces a significant reduction of the minimum joint space in the contralateral temporomandibular joint and a sustained condition remarkably increases this change.

Enzymatic synthesis of oleamide (cis-9, 10-octadecenoamide), an endogenous sleep-inducing lipid, by rat brain microsomes

The enzymatic synthesis of a novel sleep-inducing lipid, oleamide (cis-9,10-octadecenoamide), was studied using rat brain subcellular fractions as enzyme sources. We found that oleamide was formed from oleic acid and ammonia on incubation with a brain homogenate. The enzyme activity catalyzing the formation of oleamide from oleic acid and ammonia was highest in the microsomal fraction among the subcellular fractions. Boiled microsomes did not exhibit appreciable enzyme activity. These results strongly suggest that oleamide can be synthesized enzymatically in the brains of stimulated animals.

Absent myocardial I-123 BMIPP uptake in a family

A 72-year-old woman with hypertension showed no sign of myocardial accumulation of 123I-BMIPP, and 201Tl and 123I-MIBG scintigraphy demonstrated normal findings. Electrocardiography showed left axis deviation with inverted T waves in leads I, aVL, V2-6 and QT prolongation. Coronary arteriography, two dimensional echo cardiography and laboratory data showed no abnormality. Her 66-year-old sister with non-insulin-dependent diabetes mellitus also had no myocardial BMIPP uptake, but had normal 201Tl finding. ECG and chest film findings were normal. Laboratory data indicated slightly high fasted blood glucose, triglyceride and total cholesterol. Four sons of a 72-year-old woman also underwent BMIPP scintigraphy. No BMIPP uptake was also observed in her 2nd son (49 years old) and his electrocardiogram showed QT prolongation. Since these rare findings indicating no myocardial BMIPP uptake were seen in a family, we suspected that a hereditary myocardial metabolic abnormality accounted for them.

Adhesion-dependency of serum-induced p42/p44 MAP kinase activation is released by retroviral oncogenes

G1/S transition of the cell cycle is blocked when cells are cultured without cell adhesion, even if nutrients and serum are present. Shift experiments involving transfer from adhesion to suspension cultures have revealed that cell adhesion in the early half of G1 phase is required for induction of DNA synthesis. We found that activation of p42/p44 mitogen-activated protein (MAP) kinases, one of the earliest responses induced by serum stimulation, was also dependent on cell adhesion in rat F2408 and mouse Swiss3T3 fibroblast cell lines, suggesting that MAP kinase activation is a critical step in adhesion-dependent G1 progression. F2408 cell lines transformed by the v-src, v-K-ras, and v-mos oncogenes showed constitutively high MAP kinase activity, even in the absence of serum and cell adhesion, while both serum stimulation and cell adhesion were necessary to induce intensive activation of MAP kinase in a F2408 cell line transformed by the E6 and E7 genes of human papillomavirus type 16, as well as in untransformed F2408.

[Antiulcer properties of shosaiko-to]

Recently it has been reported that Shosaiko-to (SHO), a traditional Chinese medicine used for treating gastritis and hepatitis, also has been found useful for treating gastric ulcers, although no pharmacological study has yet investigated the precise antiulcer properties of SHO. Herein, the authors report on the results of a rat study in which the effects of SHO on gastric ulcers, acid secretions and potential difference of gastric mucosa (PD) were studied. SHO (100, 250 or 500 mg /kg, p.o.) significantly inhibited the development of ethanol-induced gastric lesions in a dose-dependent manner. SHO (500 mg/kg, p.o.) significantly inhibited the development of aspirin-,indomethacin- or water-immersion-stress induced gastric lesions. Sucralfate (500 mg/kg, p.o.) inhibited both ethanol- and aspirin-induced gastric lesions, and cimetidine (10 mg/kg, p.o.) inhibited aspirin-, indomethacin- or stress-induced gastric lesions. SHO (10, 30 and 100 mg/kg, i.p.) also significantly inhibited pentagastrin- and 2-deoxy-D-glucose (2-DG)-induced gastric acid secretions in a dose-dependent manner, whereas cimetidine (1 mg/kg, i.p.) inhibited a pentagastrin-induced secretion and atropine (0.05 mg/kg, i.p.) inhibited pentagastrin- or 2-DG-induced acid secretions. SHO (250, 500 or 1000 mg/kg, i.g.) significantly inhibited ethanol-induced PD reduction. Sucralfate (500 mg/kg, i.g.) inhibited the reduction, and cimetidine (250 mg/kg, i.g.) didn't inhibit it. These results indicate that SHO not only possesses the capability of protecting the rat gastric mucosa as well as sucralfate, but also is able to inhibit gastric acid secretions like cimetidine or atropine.

Ontogeny of GABA-immunoreactive cells in the primate cerebellar cortex: comparison with somatostatin-immunoreactivity

The distribution and ontogeny of GABA-immunoreactive cells were studied and compared with that of somatostatin-immunoreactivity in the primate cerebellar cortex. At embryonic day 80, we observed neither GABA-nor somatostatin-immunoreactive cells in the cerebellum. At embryonic day 110, a small number of GABA-immunoreactive cells was detectable in the granular layer only, and these cells seemed to be Golgi cells. At embryonic day 140, although almost all Purkinje cells were somatostatin-immunoreactive, a proportion of these cells was GABA-immunoreactive. At the newborn stage, most of the Purkinje cells were GABA-immunoreactive and almost all of them were also somatostatin-immunoreactive. During the postnatal stages, the number of somatostatin-immunoreactive cells decreased until postnatal day 60. At the adult stage, a large number of Purkinje cell bodies was faintly GABA-immunoreactive and a proportion of Purkinje cell dendrites was GABA-immunoreactive. In the aged animals (28 and 31 years old), a small number of Purkinje cell dendrites was GABA-immunoreactive. These findings suggest that a transition of phenotype from somatostatin to GABA occurred in Purkinje cells during development.

N-arachidonoylethanolamine (anandamide), an endogenous cannabinoid receptor ligand, and related lipid molecules in the nervous tissues

The effects of N-arachidonoylethanolamine (anandamide) and related compounds on the binding of [3H]CP55940 to rat brain synaptosomes were examined. Anandamide was shown to inhibit competitively the specific binding of [3H]CP55940 to synaptosomal membranes. The Ki value was 89 nM. In contrast, N-acylethanolamines containing saturated or monoenoic fatty acids did not exhibit high binding affinity. Several structural analogues of anandamide showed some binding activity. Among them, 2-arachidonoylglycerol is noteworthy because of its occurrence in mammalian tissues. A biosynthetic study indicated that anandamide can be synthesized via two separate synthetic pathways. The first is synthesis from free arachidonic acid and ethanolamine, and the second is the formation of N-arachidonoyl phosphatidylethanolamine (PE) from diarachidonoyl phospholipids and PE and the subsequent enzymatic release of N-arachidonoylethanolamine. The latter pathway appears to explain very well the fatty acid composition of N-acylethanolamines present in mammalian tissues.

Transacylase-mediated and phosphodiesterase-mediated synthesis of N-arachidonoylethanolamine, an endogenous cannabinoid-receptor ligand, in rat brain microsomes. Comparison with synthesis from free arachidonic acid and ethanolamine

The levels of N-arachidonoylethanolamine (anandamide), an endogenous cannabinoid-receptor ligand, and a relevant molecule, N-arachidonoylphosphatidylethanolamine (N-arachidonoylPtdEtn), in rat brain were investigated using a newly developed sensitive analytical method. We found that rat brain contains small but significant amounts of these two types of N-arachidonoyl lipids (4.3 pmol/g tissue and 50.2 pmol/g tissue, respectively). Then, we investigated how N-arachidonoylethanolamine (anandamide) is produced in the brain. We found that anandamide can be formed enzymatically via two separate synthetic pathways in the brain: enzymatic condensation of free arachidonic acid and ethanolamine; and formation of N-arachidonoylPtdEtn from PtdEtn and arachidonic acid esterified at the 1-position of phosphatidyl-choline (PtdCho), and subsequent release of anandamide from N-arachidonoylPtdEtn through the action of a phosphodiesterase. We confirmed that rat brain contains both the enzyme activities and lipid substrates involved in these reactions. Several lines of evidence strongly suggest that the second pathway, rather than the first one, meets the requirements and conditions for the synthesis of various species of N-acylethanolamine including anandamide in the brain.

Direct interaction between mitochondrial succinate-ubiquinone and ubiquinol-cytochrome c oxidoreductases probed by sensitivity to quinone-related inhibitors

The electron-transfer activities of bovine heart mitochondrial complexes I, II, and III, but not complex IV, were simultaneously inhibited by 2-alkyl-4,6-dinitrophenols to a different extent. The extent of inhibition of NADH and succinate oxidase activities by dinitrophenols was compared with that of individual complex activities using submitochondrial particles. The extent of inhibition of succinate oxidase activity by 1-methylpropyl and 1-methylbutyl derivatives was much larger than that of NADH oxidase activity. This large inhibition of succinate oxidase activity seemed not to be explainable by the extent of inhibition of individual complex activities (i.e., complexes II and III activities), based upon the homogeneous ubiquinone pool model. On the other hand, other dinitrophenols (n-propyl, 1-methylpentyl, 1-methylhexyl, and tert-butyl derivatives) very similar to the above compounds did not elicit such anomalous inhibitory action, indicating that the action of 1-methylpropyl and 1-methylbutyl derivatives is highly specific to their structure. The anomalous inhibition by these two compounds was also observed with the isolated succinate-cytochrome c oxidoreductase, in which there is no ubiquinone pool behavior [Rich, P.R. (1984) Biochim. Biophys. Acta 768, 53-79]. However, when the succinate-cytochrome c reductase of which the activity had been partially restored by adding phospholipid and exogenous quinone to the phospholipid- and ubiquinone-depleted succinate-cytochrome c reductase was assayed, the anomalous inhibitory action of interest was undetectable. These results indicated that electron-transfer between complexes II and III, which is mediated not only by free-form, but also by protein-bound ubiquinone, occurs in the mitochondrial membrane. The fact that the anomalous inhibition of succinate oxidase activity of submitochondrial particles was sensitive to changes in the external osmotic pressure which affected the total area of the particle supports this notion.

[Effects of kamikihi-to on ovariectomy-induced changes in behavior and circulation in rats]

The various symptoms that women experience in the climacteric period, such as flashing, depression, paresthesia and insomnia, have been termed the menopausal syndrome. Since Kamikihi-to (KMK) has been administered clinically for several of these symptoms, the effects of KMK were evaluated in a series of experiments using adult ovariectomized (OVX) rats. After surgery, KMK and other drugs were administered daily for 7 or 8 days until the experiments. OVX rats showed significantly higher electric shock thresholds, and KMK restored their sensitivity to electric shock in a dose-dependent manner. Furthermore, the latency of OVX rats in the step-through passive avoidance test was significantly shortened, and KMK prolonged the latency significantly. OVX rats showed a significantly decreased number of correct choices and an increased number of errors in the 8-arm radial maze task, and KMK normalized both of these parameters in a dose-dependent manner. The blood pressure of OVX rats was significantly increased, and KMK improved the blood pressure levels. These findings suggest that KMK might be useful for treatment of the menopausal syndrome, and it is considered that the improvements induced by KMK are due to other actions, such as normalization of the central nervous system, rather than sex hormones.

Influence of diethylstilbestrol, Leuprolelin (a luteinizing hormone-releasing hormone analog), Finasteride (a 5 alpha-reductase inhibitor), and castration on the lobar subdivisions of the rat prostate

The effects of various means of interfering with androgen action on rat coagulating gland, ventral prostate, lateral type 1 prostate, lateral type 2 prostate, and dorsal prostate were examined morphologically and quantitatively by assessing DNA content, wet weight, protein content, and zinc concentrations. Adult male Sprague-Dawley rats were subjected to 2 weeks of interfering with androgen action by treatment with Leuprolelin (a luteinizing hormone-releasing hormone analog), Finasteride (a 5 alpha-reductase inhibitor), or diethylstilbestrol (DES), or by physical castration. For all prostatic lobes, inhibition of 5 alpha-reductase elicited the smallest reduction in prostatic wet weight, DNA and protein contents, and zinc concentration. The most profound reductions in all parameters were elicited by castration. Treatments with DES and Leuprolelin gave intermediate effects with DES being the more effective in reducing all parameters in all prostatic lobes. Morphological changes elicited by all forms of androgen blockade were reduction of epithelial height, relative increase of connective tissue, reduction in ductal diameter, length, and number. The order of effectiveness of the various treatments on morphological features was as described above. While all forms of androgen blockade elicited similar effects throughout the prostate, differences in response to all forms of interference with androgen action were observed in different lobes of the prostate with regard to wet weight, DNA and protein contents, and zinc concentration as well as morphological effects. Regressive changes at the morphological level were particularly striking in the coagulating gland and ventral prostate, and indistinct in the lateral type 2 prostate. Prostatic zinc concentration in both normal and androgen-deprived rats was the highest in the lateral type 2 prostate and was reduced by interfering with androgen action to the greatest extent in the dorsolateral prostate (lateral type 1 and type 2, and dorsal prostate). The distribution of zinc correlated with the expression of metallothionein, which was detected by immunocytochemistry only in the lateral type 2 prostate of both normal and androgen deprived rats. Intraprostatic heterogeneity of zinc and metallothionein expression emphasizes interlobar differences in biological function within the rat prostate. The mechanism of development of regional heterogeneity within the prostate may shed light on the pathogenesis of prostatic proliferative diseases (prostatic hyperplasia and prostatic cancer) that initially owe their development to focal changes within large cell populations.