The regulation of pepsin secretion in the edible frog Rana esculenta (L.)

ABSTRACT The presence and activity of brain, pituitary and testicular β-endorphin (β-EP)-like material have been studied in the frog, Rana esculenta, using reverse-phase high-pressure liquid chromatography, coupled with radioimmunoassay and immunocytochemistry. In-vivo and in-vitro treatments with naltrexone were carried out to assess the putative physiological activity of opioid peptides. β(1–31) and (1–27), together with their acetylated forms, have been identified in brain, pituitary and testis. In particular, β-EP(1–31) concentrations peaked during July in the brain and pituitary, whilst in testes maximum concentrations were found in April and November. β-EP immunoreactivity was present in the brain within the nucleus preopticus and nucleus infundibularis ventralis while positive fibres in the retrochiasmatic regions projected to the median eminence. In the testis, interstitial cells, canaliculi of the efferent system, spermatogonia and spermatocytes showed positive immunostaining for β-EP. In intact animals, naltrexone treatment increased plasma and testicular androgen levels and this effect was confirmed in in-vitro incubations of minced testes. Naltrexone also induced a significant increase in germ cell degeneration. Our results indicated that an opioid system modulates the hypothalamus-pituitary-gonadal axis in the frog, Rana esculenta and, for the first time, we have shown that the testicular activity of a non-mammalian species may be regulated by opiates locally. Journal of Endocrinology (1993) 137, 49–57

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Hormonal control of in vitro vitellogenin synthesis in Rana esculenta liver: Effects of mammalian and amphibian growth hormone

General and Comparative Endocrinology ◽

10.1016/0016-6480(92)90235-c ◽

1992 ◽

Vol 88 (3) ◽

pp. 406-414 ◽

Cited By ~ 14

Author(s):

Oliana Carnevali ◽

Gilberto Mosgoni ◽

Kazutoshi Yamamoto ◽

Tetsuya Kobayashi ◽

Sakae Kikuyama ◽

...

Keyword(s):

Growth Hormone ◽

Rana Esculenta ◽

Hormonal Control ◽

Vitellogenin Synthesis

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Freezing tolerance of the European water frogs: the good, the bad, and the ugly

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00711.2004 ◽

2005 ◽

Vol 288 (6) ◽

pp. R1563-R1570 ◽

Cited By ~ 22

Author(s):

Yann Voituron ◽

Pierre Joly ◽

Michel Eugène ◽

Hervé Barré

Keyword(s):

Body Mass ◽

Accumulation Rate ◽

Freeze Tolerance ◽

Rana Esculenta ◽

Rana Ridibunda ◽

European Water ◽

Water Frogs ◽

European Water Frogs ◽

Mass Accumulation ◽

Rana Lessonae

Survival and some physiological responses to freezing were investigated in three European water frogs ( Rana lessonae, Rana ridibunda, and their hybridogen Rana esculenta). The three species exhibited different survival times during freezing (from 10 h for R. lessonae to 20 h for R. ridibunda). The time courses of percent water frozen were similar; however, because of the huge differences in body mass among species (from 10 g for Rana lessonae to nearly 100 g for Rana ridibunda), the ice mass accumulation rate varied markedly (from 0.75 ± 0.12 to 1.43 ± 0.11 g ice/h, respectively) and was lowest in the terrestrial hibernator Rana lessonae. The hybrid Rana esculenta exhibited an intermediate response between the two parental species; furthermore, within-species correlation existed between body mass and ice mass accumulation rates, suggesting the occurrence of subpopulations in this species (0.84 ± 0.08 g ice/h for small R. esculenta and 1.78 ± 0.09 g ice/h for large ones). Biochemical analyses showed accumulation of blood glucose and lactate, liver glucose (originating from glycogen), and liver alanine in Rana lessonae and Rana esculenta but not in Rana ridibunda in response to freezing. The variation of freeze tolerance between these three closely related species could bring understanding to the physiological processes involved in the evolution of freeze tolerance in vertebrates.

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Evidence for a intimate relationship between mast cells and nerve fibers in the tongue of the frog,Rana esculenta

RENDICONTI LINCEI ◽

10.1007/bf03002322 ◽

1997 ◽

Vol 8 (2) ◽

pp. 93-100 ◽

Cited By ~ 5

Author(s):

Gabriella Chieffi Baccari ◽

Sergio Minucci

Keyword(s):

Mast Cells ◽

Intimate Relationship ◽

Rana Esculenta ◽

Nerve Fibers

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Neural elements of the pineal complex of the frog, rena esculenta, I: Centrally projecting neurons

Visual Neuroscience ◽

10.1017/s0952523800005150 ◽

1990 ◽

Vol 4 (05) ◽

pp. 389-397 ◽

Cited By ~ 3

Author(s):

Peter Ekström ◽

Hilmar Meissl

Keyword(s):

Pineal Organ ◽

Photoreceptor Cells ◽

Rana Esculenta ◽

Projection Neurons ◽

Pineal Complex ◽

Bipolar Neuron ◽

Neural Organization ◽

Hand Functions ◽

Frontal Organ ◽

Pineal Tract

AbstractThe pineal complex of anuran &hibians is a directly photosensory organ, encompassing both an extracranial portion, the frontal organ, and an intracranial portion, the pineal organ proper. The projection neurons of the frontal organ respond differentially according to the wavelengths of the light stimuli. The pineal organ, on the other hand, functions mainly as a luminosity meter. Most of its centrally projecting neurons respond to all increases in ambient illumination with decreases in spontaneous firing of action potentials, although some neural units in the pineal organ may respond according to wavelength. This difference in responses to light stimulation may be reflected in the neural organization of the two parts of the pineal complex. In the present study, we have analyzed the morphology of the projection neurons of the frontal and pineal organs of the frog,Rana esculenta, by backfilling of the neurons with horseradish peroxidase through their cut axons. In the pineal organ, several types of centrally projecting neurons were observed: peripherally situated unipolar and multipolar neurons, the dendrites of which extend into a superficial axon plexus that surrounds the pineal epithelium; smaller unipolar, bipolar, or multipolar neurons situated close to the central pineal tract; and radially oriented bipolar neurons, with short dendritic processes oriented towards the lumen of the pineal organ. This latter type was strongly reminiscent of photoreceptor cells. The centrally projecting neurons of the frontal organ were multipolar, and situated in the ventral part of the organ. One photoreceptor-like bipolar neuron was observed in one frontal organ. The neurons of the frontal organ did not form a superficial plexus of neurites. This difference may relate to the different ratio of chromaticity/luminosity units in the frontal and pineal organs.

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