Morphological and immunohistochemical comparison of the pituitary gland between a tropical Paracheirodon axelrodi and a subtropical Aphyocharax anisitsi characids (Characiformes: Characidae)

Cardinal tetra Paracheirodon axelrodi and bloodfin tetra Aphyocharax anisitsi are two species of characids with high trade value as ornamental fish in South America. Although both species inhabit middle water layers, cardinal neon exhibits a tropical distribution and bloodfin tetra a subtropical one. Generally, these species are difficult to grow, so it becomes essential to know some key components of the neuroendocrine system to achieve their reproduction in captivity. Considering the importance of deepening the knowledge of the reproductive physiology through functional morphology, for the first time in this work we performed an anatomical, morphological and immunohistochemical analysis of the pituitary gland of these two species. In both species, a leptobasic type pituitary is found in the ventral zone of the hypothalamus and it is characterized by a neurohypophysis which has a well-developed pituitary stalk and a globular adenohypophysis. The pituitary components, characterized by histochemistry and immunohistochemistry, shows a distribution pattern of cells types similar to other teleost species, with only slight differences in the distribution of βFSH and βLH for P. axelrodi.(AU)

El cardenal tetra Paracheirodon axelrodi y el tetra Aphyocharax anisitsi son dos especies de carácidos con alto valor comercial como peces ornamentales en América del Sur. Aunque ambas especies habitan en las capas medias de agua, el neón cardenal exhibe una distribución tropical, mientras que el tetra cola roja una distribución subtropical. En general estas especies son difíciles de cultivar, por lo que es esencial conocer algunos componentes clave de los sistemas neuroendocrinos para lograr su reproducción en cautiverio. Considerando la importancia de profundizar en el conocimiento de la fisiología reproductiva a través de la morfología funcional, en este trabajo realizamos, por primera vez, un análisis anatómico, morfológico e inmunohistoquímico de la glándula pituitaria de estas dos especies. En ambas especies, la hipófisis, del tipo leptobásica, se encontró en la zona ventral del hipotálamo y se caracteriza por una neurohipófisis con un tallo hipofisario bien desarrollado y una adenohipófisis globular. Los componentes hipofisarios, caracterizados por la histoquímica y la inmunohistoquímica, mostraron un patrón de distribución de tipos de células similares a otras especies de teleósteos, con solo pequeñas diferencias en la distribución de βFSH y βLH para P. axelrodi.(AU)

Estradiol antagonistic effects of winter cherry extract on pituitary and hypothalamic GOPD activities

Intraperitoneal administration of an aqueous extract of winter cherry fruits [Physalis alkekengi] to adult cycling female rats diminished pituitary glucose 6-P dehydrogenase [G6PD] activity by 35% and that of the basomedial hypothalamus [BMH] by 23%. Daily doses of 1.88, 3.75, 7.5, and 15 micro g beta-estradiol administered to such animals for a period of 6-9 days increased pituitary G6PD activity by 16,30,60, and 94% and that of BMH by 14,19,30, and 52%, respectively. Combined administration of a given dose of the aqueous extract along with the above doses of beta-estradiol for 8-9 days reduced G6PD inhibitory effect of the aqueous extract on both the pituitary and BMH. In this manner the pituitary enzyme was inhibited by 14% [1.88 micro g beta-estradiol], 7% [3.75 micro g estradiol] and activated by 37% [7.5 micro g estradiol] and 62% [15 micro g estradiol]. Corresponding values for the hypothalamic enzyme were inhibitions of 21% [1.88 micro g estradiol], 18% [3.75 micro g estradiol], 7% [7.5 micro g estradiol] and activation of 2% [15 micro g estradiol]. The estrogen antagonistic effect of this aqueous extract on the brain is discussed in terms of its possible action on the inhibition of the hypothalamic gonadotropin releasing hormone and the pituitary luteinizing hormone release, thus affecting ovulation and pregnancy