Cytochemical localization of adenylate cyclase activity in rat olfactory cells

Cyclic 3',5'-nucleotide phosphodiesterase activity was demonstrated cytochemically in the rat olfactory mucosa using cyclic AMP as substrate. Strong activity was observed on the plasma membrane of the cilia, dendritic knob and axon of olfactory cells; weak activity was apparent on the membrane of the dendritic shaft and cell body. This suggests that the cyclic AMP produced by odorant-sensitive adenylate cyclase in the dendritic terminal acts mainly in its original site and to a lesser extent in the dendritic shaft and cell body. The enzyme also hydrolysed cyclic GMP but the hydrolysis was not as great as in the case of cyclic AMP. Besides its presence in olfactory cells, enzymatic activity was also observed on the plasma membrane of basal cells and certain supporting cells with an astrocyte-like morphology.

Section: Introductionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Cytochemical localization of cyclic 3?,5?-nucleotide phosphodiesterase activity in the rat olfactory mucosa

Asanuma

Nomura

1993

“…Particularly, fixation inhibits the activity and responsiveness of adenylate cyclase to a variable degree depending on the nature of the fixative and on the type of tissue (Poeggel et aI., 1984). Moreover, quantitative biochemical analyses have demonstrated that fixation in either glutaraldehyde alone (Schultze, 1982;Ogawa eta]., I987) or in a mixture of paraformaldehyde and glutaraldehyde (Asanuma & Nomura, 1991) substantially reduces adenylate cyclase activity.…”

Section: Discussionmentioning

confidence: 99%

Cytochemical localization of adenylate cyclase in the sodium-transporting epithelium isolated from frog skin

Richards

1994

A modified cytochemical technique with 5'-adenylylimidodiphosphate as substrate, was used to examine the distribution of adenylate cyclase in cells comprising the transepithelial Na+ transport pathway in isolated frog skin epithelium. Particular attention was paid to the effects of fixation on the activity and localization of adenylate cyclase. Fixation in glutaraldehyde alone or in combination with paraformaldehyde reduced the amount of reaction product, while better results were obtained using unfixed tissues. Optimum results were obtained following stimulation of adenylate cyclase with forskolin and in the presence of specific metabolic inhibitors. Adenylate cyclase was localized in the basolateral membranes of the principal cells which constitute a functional syncytium for Na+ transport and was absent from the apical membranes of the outermost granulosum cells. This distribution is consistent with the transepithelial Na+ transport model and defines the functional morphology of the cells involved in Na+ transport across frog skin. The results are compatible with the process of Na+ re-absorption across other epithelial cells, verifying that frog skin is a convenient model-tissue to study Na+ transport mechanisms. Adenylate cyclase was also found in membranes of the mitochondria-rich cells, a minor and parallel Na+ transporting pathway.

“…In rat olfactory mucosa, AC activity was detected ultracytochemically by stimulation with nonhydrolysable GTP analogues and forskolin (Asanuma & Nomura, 1991) and an AC that mediates olfactory transduction for a wide variety of odorants was identified in olfactory receptor cells of bullfrog and rat (Anholt, 1988;Lowe et al, 1989;Pfeuffer et at., 1989;Ronnett et al, 1991). If the localization of AC reaction product in olfactory cells is related with this event, the particulate GC in these cells could be associated with the transduction of stimuli which could not be detected.The presence of both GC and AC at the surface of olfactory mucosa in association with olfactory cells could be indicative that the two enzymes have complementary activities in these cells.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies identified an adenylate cyclase (AC) that mediates olfactory transduction for a wide variety of odorants through cAMP as second messenger in olfactory cells of bullfrog and rat (Anholt, 1988;Lowe et aL, 1989;Pfeuffer et al, 1989;Ronnett et aI., 1991), and recently AC activity was detected in olfactory cells of rat ultracytochemically (Asanuma & Nomura, 1991).…”

Section: Introductionmentioning

confidence: 99%

Ultracytochemical localization of particulate guanylate cyclase after stimulation with natriuretic peptides in lamb olfactory mucosa

Spreca

Rambotti

1994

The ultracytochemical localization of particulate guanylate cyclase has been studied in lamb olfactory mucosa after activation with rat atrial natriuretic factor (rANF), porcine brain natriuretic peptide (pBNP), porcine C-type natriuretic peptide (pCNP) or rat brain natriuretic peptide (rBNP). Particulate guanylate cyclase is the receptor for these peptides and recently two subtypes of the cyclase have been identified. These isoforms are stimulated differently by ANF, BNP and CNP. Under our experimental conditions, rANF, pCNP and pBNP were strong activators of particulate guanylate cyclase in lamb olfactory mucosa, as demonstrated by the presence of reaction product. Samples incubated in basal conditions without rANF, pCNP or pBNP, or samples incubated in presence of rBNP did not reveal any cyclase activity. The rANF-stimulated cyclase activity was localized in the apical portion of olfactory epithelium. pCNP-stimulated guanylate cyclase was detected to the lamina propria in association with secretory cells of Bowman's glands and with cells in close relation with Bowman's glands (elongated cells and myoepithelial cells). The cyclase activity stimulated by pBNP was limited to cells of Bowman's glands. The present data indicate that ANF and CNP are recognized by different receptors and that BNP and CNP bind to the same receptor.