Progestin binding in mammary tissue of prepartum,nonlactating and postpartum,lactating cows

Binding of [³H]R5020 (17,21-dimethyl-19-nor-4,9-pregnadiene-3, 20-dione) to bovine mammary cytosol indicated the presence of progestin binding sites of high-affinity and low-capacity in tissue from prepartum, nonlactating and from postpartum, lactating cows. To prevent binding of [³H]R5020 to glucocorticoid binding sites, a 200-fold molar excess of nonradioactive cortisol was included during all incubations, thus specific binding was limited to progestin binding sites. Nonradioactive R5020 and progesterone effectively inhibited [³H]R5020 binding to progestin binding sites, while estradiol-17β, dihydrotestosterone (17β-hydroxy-5α-androstan-3-one), dexamethasone (9-fluoro-11β, 17, 21-trihydroxy-16α-methyl-1,4-pregnadiene-3,20-dione) or additional cortisol were ineffective. Dissociation constants for specifically bound [³H]R5020 in cytosol from mammary tissue of nonlactating and lactating cows were nearly identical, averaging 1.9 ( ± 0.3) and 0.8( ± 0.2) × 10?⁹M, respectively. However, binding capacities (fmol/mg cytosolic protein) were greater in cytosol from prepartum, nonlactating (179 ± 53) than postpartum, lactating (41 ± 15) cows. Specific binding components in cytosol from lactating cows sedimented in the 6-7S region on linear sucrose density gradients. When subjected to isoelectric focusing, specific binders with isoelectric points (pI) of approximately 6.1, 7.9 and 8.3 were resolved. The decrease in number of binding sites during lactation was due to the virtual absence of the anionic binding species, suggesting that their presence is necessary for progesterone to inhibit milk secretion.     

Serotonin-containing neurones in vertebrate retinas

Abstract: It has been established by a combination of HPLC and electrochemical detection that frog, lizard, goldfish, rabbit, and bovine retinas contain both dopamine and serotonin. Immunohistological and immunoradiographical methods show that serotonin is localised in amacrine perikarya and processes situated in the inner plexiform layers of frog, lizard, and goldfish retinas. The amount of serotonin in the mammalian retina appears to be too low for detection in neurones. The serotonin in the bovine retina is located mainly in the inner nuclear and plexiform layers, suggesting that the amine is present in the same types of cells as found for frog, lizard, and goldfish retinas. Retinas incubated in [³H]serotonin showed that radioactivity is associated with processes in the inner plexiform layer and amacrine perikarya. These results suggest that the neuronal elements that contain endogenous serotonin also have the capacity to accumulate exogenous amine and are consistent with the opinion that serotonin has a neuronal function in retinas of a variety of vertebrates.     

Comparative evaluation of macrophage stimulation and depression on tumor growth and macrophage content and function in mice

Summary In a syngeneic murine adenocarcinoma model, the administration of glucan, an RE stimulant, inhibited tumor growth and increased tumor macrophage populations. Conversely, the administration of methyl palmitate, an RE depressant, potentiated tumor growth and decreased the number of tumor macrophages. Glucan and methyl palmitate also produced diverse alterations in serum lysozyme levels that reflected their contrasting influences on RE functional status, thus supporting the role of serum lysozyme as an index of macrophage function. The diverse results produced by macrophage stimulation or depression in regard to tumor growth, tumor macrophage population, and serum lysozyme concentration indicate that a relationship may exist between macrophage functional activity and host resistance to neoplasia.