dibutyryl-cyclic-gmp and 1-2-dioctanoylglycerol

The effects of beta-phorbol 12,13-dibutyrate (PDBu) on the discharge properties of slowly conducting knee joint afferents (group III and group IV fibers) were studied to determine the role of protein kinase C in nociception. Extracellular single unit recordings were made from small filaments dissected from the medial articular nerve in cats anesthetized with alpha-chloralose. PDBu was applied intra-arterially close to the joint in concentrations of 10(-6) up to 10(-4) M. The afferents were classified as low-threshold and high-threshold units with regard to their sensitivity to passive noxious and innocuous movements of the knee joint. Following PDBu application, an excitation occurred in 28% of the group III and in 40% of the group IV fibers. An enhancement of responses to passive movements of the joint (sensitization) occurred in 37% of group III and 19% of group IV afferents. In summary, 37.5% of the low-threshold and 50% of the high-threshold fibers proved to be sensitive to PDBu. Most of the PDBu-positive units responded also to bradykinin, whereas only a few PDBu-positive units were sensitive to prostaglandin I2 and E2. We conclude from these results that, in a distinct population of slowly conducting joint afferents, protein kinase C is likely to be involved in the process of transduction. Thus, pain and hyperalgesia may be mediated at least partly by intracellular mechanisms that are linked to protein kinase C.

Topics: Animals; Bradykinin; Bucladesine; Cats; Dibutyryl Cyclic GMP; Diglycerides; Dinoprostone; Epoprostenol; Hindlimb; Knee Joint; Neural Conduction; Neurons, Afferent; Nociceptors; Phorbol 12,13-Dibutyrate; Protein Kinase C; Signal Transduction

We examined effects of modulators of protein kinases and phosphatases on the kinetics of mouse sperm capacitation. The chlortetracycline fluorescence assay was used to monitor the process of capacitation (in terms of the appearance of the B pattern). The treatment of sperm with dibutyryl cyclic AMP (cAMP) or dibutyryl cGMP resulted in a higher percentage B pattern at various times during capacitation compared with the control. The addition of 100 microM H8 inhibited the cyclic nucleotide-dependent stimulation of capacitation. Tumor promotors, 12-O-tetradecanoyl phorbol 13-acetate (TPA; a stimulator of protein kinase C) and okadaic acid (an inhibitor of protein phosphatases 1 and 2A), induced a rapid appearance of the B pattern (15 min after addition) and maintained a percentage B pattern similar to that of the control in the later period of capacitation. An inhibitor of protein kinase C, staurosporine, inhibited the TPA-dependent acceleration of capacitation. Furthermore, the addition of genistein, an inhibitor of protein tyrosine kinases, resulted in a strong inhibition of capacitation. All agents tested did not affect sperm motility. These data suggest that protein phosphorylation and dephosphorylation may play regulatory roles in mediating mouse sperm capacitation.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Alkaloids; Animals; Bucladesine; Chlortetracycline; Dibutyryl Cyclic GMP; Diglycerides; Ethers, Cyclic; Fluorescence; Genistein; Isoflavones; Isoquinolines; Male; Mice; Okadaic Acid; Peptide Fragments; Phorbol Esters; Phosphoprotein Phosphatases; Piperazines; Protein Kinase C; Protein Kinase Inhibitors; Protein Kinases; Sperm Capacitation; Staurosporine; Tetradecanoylphorbol Acetate

Ejaculated spermatozoa from brush-tailed possums and tammar wallabies were washed by a 'swim up' procedure into Hanks Balanced Salt Solution (HBSS), and then exposed to test solutions. Spermatozoa were incubated at 33 degrees C, or room temperature when long-term sperm survival (greater than 10 h) was required. Exposure of spermatozoa to calcium ionophore A23187, cyclic nucleotides, phosphoinositide pathway intermediates, lysophospholipids, trypsin or 'capacitating' high ionic-strength medium (380 mosmol) followed by 3% bovine serum albumin for periods up to 24 h did not induce acrosomal loss. However, there were major changes within the acrosome: large numbers of empty membrane-bound vesicles were formed, the electron density of the acrosomal matrix decreased and the acrosome swelled slightly. The origin of the vesicles is unclear but the acrosomal membranes and the plasma membrane remained intact.

Topics: Acrosome; Animals; Bucladesine; Calcimycin; Cell Membrane; Cells, Cultured; Dibutyryl Cyclic GMP; Diglycerides; Lysophosphatidylcholines; Macropodidae; Male; Marsupialia; Microscopy, Electron; Sperm Capacitation; Spermatozoa; Tetradecanoylphorbol Acetate; Trypsin