Biomedical subjects
Publications and source records attributed to J Kunert-Radek.
The influence of gonadotropic hormones on the ultrastructure of rat pinealocytesin short-term organ culture was studied. Human chorionic gonadotropin (HCG), as well as pregnant mare serum gonadotropin (PMSG), caused a marked activation of pinealocytes. An hypothesis is discussed implying the presence of a feedback mechanism between the pineal organ and the hypothalamo-hypophysial system.
The effects of pilocarpine and atropine on the mitotic incidence in the anterior pituitary in male and ovariectomized estradiol-pretreated female rats was investigated. It was shown that pilocarpine stimulated, while atropine inhibited, the anterior pituitary mitotic activity. It was also shown that carbachol enhanced the mitotic incidence in the organ-cultured anterior pituitary and its effect was blocked by scopolamine. The existence of the muscarinic cholinergic receptor within the anterior pituitary, as well as its involvement in the control of the anterior pituitary mitotic activity, is suggested.
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The effect TRH and thyroxine (T4) in vitro on the content of cAMP in the anterior pituitary gland in rat have been investigated. Thyroxine did not significantly affect this concentration, but TRH produced approximately a two-fold increase in the pituitary cAMP content. Preincubation of the anterior pituitary together with T4--under the conditions when the latter inhibited both proliferative and secretory response of the gland to TRH--did not prevent the elevation of cAMP due to TRH. It is assumed that T4 must have exerted its inhibitory effect outside of the cyclic AMP system.
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TRH increased cell proliferation in organ-cultured rat adenohypophysis. Thyroxine by itself had no effect on adenohypophysial cell proliferation in vitro but inhibited the mitogenic effect of TRH.
Mitotic indices were counted in adenohypophysial fragments cultured in vitromthe cultures exposed to 17-beta oestradiol, synthetic thyrotropin releasing hormone (TRH) and dibutyryl cyclic AMP showed a higher number of mitoses as compared with respective controls. However, theophylline decreased the mitotic index in cultured adenohypophysis.
Ultrastructure of adenohypophysis in organ culture exposed to thyrotropin releasing hormone or dibutyryl cyclic adenosine 3',5'-monophosphate has been investigated. The features of increased secretory activity of glandular cells as well as the occurrence of a strongly osmiophilic substance in the intercellular spaces was observed in cultures exposed to both investigated factors.
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The effects of native somatostatin-14 (SS-14) and of its two analogues, octreotide and CH-275, on the activity of tyrosine kinases (TK) in two rodent tumors (rat pituitary tumor and murine colonic cancer) were studied in vitro. The activity of TK was measured in tissue homogenates using gamma[(32)P]ATP as the donor of the phosphoryl group and poly(Glu(80), Tyr(20)) as a substrate. It was found that native SS-14 inhibited TK activity in both investigated tumors. Octreotide, which acts preferentially via somatostatin receptor subtype 2 (SSTR2), was very effective in inhibiting TK activity in the rat pituitary tumor, but it is a rather weak inhibitor of TK activity in murine colonic cancer. CH-275, a selective ligand of the SSTR1 subtype of SS receptors, suppressed TK activity in the pituitary tumor but was ineffective in the colonic cancer. It is hypothesized that the effect of neuropeptide somatostatin (SS-14) on murine colonic cancer is exerted via the subtype of receptor which does not interact with CH-275 and has no or low affinity for octreotide (SSTR 4, 3 or 5?).
Parkinson's disease (PD) is characterized by a markedly decreased number of nigrostriatal dopaminergic neurons. The pathogenesis of PD is still unknown; among other etiological factors, immunological abnormalities have been suggested. Recently, interleukin-2 (IL-2) has been hypothesized to be an endogenous cytokine that regulates striatal dopaminergic function. We examined the plasma concentrations of IL-1, IL-2, IL-6 and blood levels of ACTH, cortisol and prolactin of 21 patients with PD without any previous treatment. Age- and sex-matched subjects without any neurological or immune disorders were used as controls. Significantly higher serum concentrations of IL-2 in patients with PD were found. Treatment with antiparkinsonian drugs reduced IL-2 levels in these patients. Our results suggested a functional relationship between central dopaminergic and immune systems and a possible involvement of the latter in the pathogenesis of PD.
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The effects of diazepam (1-100 microM) on the incorporation of 3H-thymidine into DNA of the mouse spleen lymphocytes in vitro have been investigated. A dose-dependent inhibition of lymphocyte DNA synthesis has been found. A 70% inhibition occurred with 100 microM diazepam concentration.
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The effects of NMDA and quiscalate on proliferation of primary cell cultures of human glioma, rat estrogen induced pituitary tumor and mouse spleen lymphocytes were investigated in vitro. The tritiated thymidine incorporation into DNA was used as an index of cell proliferation. Neither NMDA nor quiscalate affected the tritiated thymidine incorporation in the cell cultures herein studied. This finding contradicts the idea of the involvement of EAA receptors in the control of cell proliferation although does not exclude it.