Generation of potent cytotoxic T lymphocytes against castration-resistant prostate cancer cells by dendritic cells loaded with dying allogeneic prostate cancer cells.

To induce a potent cytotoxic T lymphocyte (CTL) response in dendritic cell (DC)-based immunotherapy against prostate cancer, various tumour antigens should be loaded onto DCs. The aim of this study was to establish a method of immunotherapy for castration-resistant prostate cancer (CRPC) using prostate cancer-specific CTLs generated in vitro by DCs. Monocyte-derived DCs from patients with CRPC were induced to mature using a standard cytokine cocktail (in IL-1ß, TNF-α, IL-6 and PGE(2) : standard DCs, sDCs) or using an α-type 1-polarized DC (αDC1) cocktail (in IL-1ß, TNF-α, IFN-α, IFN-γ and polyinosinic:polycytidylic acid) and loaded with the UVB-irradiated CRPC cell line PC-3. Antigen-loaded DCs were evaluated by morphological and functional assays. The αDC1s significantly increased the expression of several molecules related to DC maturation, regardless of whether the αDC1s were loaded with tumour antigens or not, compared to sDCs. The αDC1s showed a higher production of interleukin-12 both during maturation and after subsequent stimulation with CD40L, which was not significantly affected by loading with tumour antigens, as compared to standard DCs (sDCs). Prostate cancer-specific CTLs against autologous CRPC cells were successfully induced by αDC1s loaded with dying PC-3 cells. Autologous αDC1s loaded with an allogeneic CRPC cell line can generate greater CRPC-specific CTL responses as compared to sDCs and may provide a novel source of DC-based vaccines that can be used for the development of immunotherapy in patients with CRPC.

Relationship of inferior olive-climbing fibers to p,p'-DDT-induced myoclonus in rats.

The effects of 3-acetylpyridine (3-AP), which destroys the inferior olive, and harmaline, which stimulates inferior olive-climbing fiber activity, on DDT-induced myoclonus, wee studied in rats. 3-AP shortened and harmaline delayed the time of onset of myoclonus after intragastric administration of DDT. 3-AP also counteracted the antimyoclonic action of L-5-hydroxytryptophan plus chlorimipramine, clonazepam and phenoxybenzamine in this animal model. The results suggest that these antimyoclonic agents require an intact olivocerebellar pathway for their action.

Role of prostaglandins in the antimyoclonic action of clonazepam.

Possible involvement of prostaglandins (PG) in the antimyoclonic action of clonazepam was examined in the p,p'-DDT-animal model of myoclonus. PG synthesis inhibitors and the PG antagonist polyphloretin phosphate (PPP) counteracted the antimyoclonic action of clonazepam in mice. PGE2 reduced DDT-induced myoclonus; this effect was blocked by PPP. Another antimyoclonic drug combination, L-5-hydroxytryptophan plus chlorimipramine, was not blocked by PPP or indomethacin. The antimyoclonic action of clonazepam may be mediated by enhancement of PG synthesis.

Effect of thiamine deficiency on brain serotonin turnover.

Serotonin turnover has been investigated in regional brain areas of rats made thiamine deficient by pyrithiamine (PT). Following intracisternal injection of [14C]5-hydroxytryptamine ([14C]5-HT), a marked increase in the accumulation of [14C]5-hydroxyindoleacetic acid ([14C]5-HIAA) was found in the medulla-pons, hypothalamus and cerebral cortex. [14C]5-HT levels were normal in all of the brain areas except the cerebral cortex which had an increase of 58%. The ratio of [14C]5-HIAA/[14C]5-HT was significantly increased in every brain region of PT-treated rats except the cerebral cortex. Part of this increase in [14C]5-HIAA was shown to be due to impairment of active transport of this 5-HT metabolite out of the brain. However, increased 5-HT synthesis in the cerebellum, hypothalamus, striatum, hippocampus and cerebral cortex was demonstrated by measurement of 5-HT accumulation after inhibition of brain monoamine oxidase. PT-induced increase in endogenous 5-HIAA in the medulla-pons occurred simultaneously with the onset of neurological signs and both parameters were reversible by thiamine administration. These results suggest that acute thiamine deficiency, induced by PT, both increases brain 5-HT synthesis and impairs 5-HIAA efflux from the brain. There is a close correlation between neurological manifestations and changes in brain 5-HT metabolism in acute thiamine deficiency.

Behavioral and biochemical effects of para-methoxyphenylethylamine.

p-methoxyphenlethylamine (p-MPEA) induces the "serotonin syndrome" in mice which consists of lateral head weaving, Straub tail, hindlimb abduction, tremor, hyperactivity, reciprocal fore-paw treading, salivation and piloerection. These p-MPEA-induced behavioral signs were partially prevented by pretreatment with serotonin (5HT) uptake blockers (fluoxetine, chlorimipramine, Org 6582) and 5HT receptor blockers (methiothepin, methysergide, cinnanserin) but not by two depletors of brain 5HT (p-chlorophenylalanine, reserpine). p-MPEA selectively released 5HT and inhibited 5HT uptake from mouse whole brain synaptosomes. The concentrations of both 5HT and 5-hydroxyindoleacetic acid (5HIAA) in whole mouse brain were increased at 1 and 2 hours after injection of p-MPEA (50 mg/kg). The effect of p-MPEA on displacement of specific tritiated 5HT binding to membranes from mouse brain was considerably less than that of p-chlorophenylethylamine (p-CPEA), p-methoxytryptamine (pMT) and quipazine. Thus p-MPEA may induce the "serotonin syndrome" predominantly by releasing 5HT from presynaptic nerve terminals.

DDT-induced myoclonus: serotonin and alpha noradrenergic interaction.

p,p'-DDT (600 mg/kg) produces myoclonic activity in mice which can be reduced by L-5-hydroxytryptophan (L-5HTP) (200 mg/kg), H75/12 (25 mg/kg), serotonin uptake blockers and two alpha-receptor blockers, phenoxybenzamine (5 mg/kg) and trazodone (5 mg/kg). Decreasing endogenous brain serotonin by pretreatment with p-chlorophenylalanine (400 mg/kg i.p.) blocked the antimyoclonic action of all of these drugs except L-5HTP. Seven other alpha-receptor blockers (phentolamine, tolazoline, yohimbine, azapetine, aceperone, nicergoline and prazosin) potentiated the antimyoclonic activity of a small dose of L-5HTP (50 mg/kg) in this animal model. We postulate that an alpha noradrenergic inhibitory synapse may be located in the neural circuit connecting a serotonergic neuron to the final motor response (p,p'-DDT-induced myoclonus).

Serotonin-norepinephrine interactions in the tremorolytic actions of phenoxybenzamine and trazodone.

Phenoxybenzamine (5 mg/kg IP) and trazodone (5 mg/kg IP) reduced tremors produced in mice by administration of oxotremorine (10 mg/kg), harmaline (80 mg/kg), catechol (60 mg/kg), kepone (200 mg/kg) and clonidine (100 mg/kg). Azapetine (10 mg/kg IP) in combination with L-5-hydroxytryptophan (50 mg/kg IP) reduced the tremor induced by oxotremorine, catechol, kepone and clonidine. In mice with lower thoracic spinal cord transection, phenoxybenzamine and trazodone reduced catechol-induced tremor above and below the site of transection. These findings suggest that an alpha noradrenergic-serotonergic neuronal balance in the spinal cord may modulate tremors of different etiologies.

p,p'-DDT-induced neurotoxic syndrome: experimental myoclonus.

p,p'-DDT (100 to 600 mg per kilogram orally) produced spontaneous and stimulus-sensitive myoclonus in mice and rats. Drugs that enhance brain serotonergic activity reduced p,p'-DDT-induced myoclonus, and serotonin antagonists invariably aggravated this syndrome. p,p'-DDT-treated rats had increased concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in seven regional areas, but serotonin was increased only in the midbrain and cerebellum. We postulate that p,p'-DDT-induced myoclonus may be causally related to blockage of serotonin receptors or inhibition of serotonin release into the synapse, resulting in functional deficiency of this neurotransmiter at the receptor site.