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Effects of administration of glucagon on the plasma and hepatic contents of the thyroid hormones in the lizard Podarcis sicula
No full textAnnual variations of thyroid activity in the lizard Podarcis sicula (Squamata, Lacertidae).
No full textEffects of administration of glucagon on the plasma and hepatic contents of the thyroid hormones in the lizard Podarcis sicula
No full textThe thyroid of Podarcis s. sicula Raf. : modification induced by glucagon administration.
No full textPossible relationship between the activity of the adrenal gland and the subcommissural organ in the lizard Lacerta s. sicula Raf. Effects of ACTH Administration during winter.
No full textIn order to study the possible functional relationship between the adrenal gland and the subcommissural organ (SCO) in the lizard Lacerta s. sicula Raf., ACTH was administered to some specimens of this species in January when both the adrenal gland and the subcommissural organ have a very low activity. In comparison to untreated controls, the adrenals of animals treated with ACTH showed clear signs of stimulation, presenting enlarged blood vessels, very few lipid droplets, numerous polymorphic mitochondria and abundant tubular smooth endoplasmic reticulum. In addition, a distinct increase in secretory material was observed in the subcommissural cells of specimens treated with ACTH. These cells showed large cisternae of the rough endoplasmic reticulum filled with granular material in the basal region, numerous secretory granules of two types in the paical region and a reduced number of microvilli on the free cell surface. These findings, together with the results of preceding studies, lead the authors to the consideration that steroid hormones might play a role in the regulation of the secretory activity of the SCO
Effects of adrenaline administration on the interrenal gland of the newt, Triturus carnifex: evidence of intra-adrenal paracrine interactions.
No full textABSTRACT
The existence of paracrine control of steroidogenic activity by adrenochromaffin cells in Triturus carnifex was investigated by in vivo noradrenaline (NA) administration. The effects were evaluated by examination of the ultrastructural morphological and morphometrical features of the tissues as well as the serum levels of aldosterone, NA, and adrenaline (A). In March and July, NA administration increased aldosterone release (from 187.23 ± 2.93 pg/ml to 878.31± 6.13 pg/ml in March; from 314.60 ± 1.34 pg/ml to 622.51± 2.65 pg/ml in July) from steroidogenic cells. The cells showed clear signs of stimulation, as evidenced by a strong reduction of lipid content.
Moreover, NA administration decreased the mean total number of secretory vesicles in the chromaffin cells in March (from 7.24 ± 0.18 granules/μ2 to 5.57 ± 1.88 granules/ μ2) and July (from 7.74 ± 0.74 granules/ μ2 to 6.04 ± 1.13 granules/ μ2). In March, however, when T.carnifex chromaffin cells contain both catecholamines, NA (3.88 ± 0.13 granules/ μ2) and A (3.36 ± 0.05 granules/ μ2) in almost equal quantities, NA administration reduced A content (1.29 ± 1.04 granules/ μ2) in the chromaffin cells, enhancing adrenaline secretion (from 681.27 ± 1.83 pg/ml to 1527.02 ± 2.11 pg/ml). In July, when the chromaffin cells contain almost exclusively NA granules (NA: 7.42 ± 0.86 granules/ μ2; A: 0.32 ± 0.13 granules/ μ2), NA administration reduced the number of NA granules (5.45 ± 1.10 granules/ μ2), thereby increasing noradrenaline release from the chromaffin cells (from 640.19 ± 1.65 pg/ml to 1217.0 ± 1.14 pg/ml). The results of this study indicate that NA influences the steroidogenic cells, eliciting aldosterone release. Noradrenalin effects on the chromaffin cells, increase of NA or A secretion, according to the period of chromaffin cell functional cycle, may be direct and/or mediated through the steroidogenic cells. The existence of intra-adrenal paracrine interactions in T. carnifex is discussed.
J. Morphol. 259:33–40, 2004
Modificazioni nella distribuzione dei due tipi di cellule cromaffini nella surrenale di Podarcis s. sicula Raf. dopo somministrazone di ACTH e cortisone
No full textFurther observation on the relationship between the S.C.O. and the adrenal gland of Lacerta s.sicula Raf.: Effects of oestrogen administration during summer.
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