Gabriel Gutiérrez Ospina

Cells positive for microtubule-associated protein 1B (MAP 1B) are present along rat and human efferent ductules and epididymis.

Microtubule-associated protein 1B (MAP 1B) is a neuronal cytoskeleton marker with predominant expression in the developing nervous system. The present study provides evidence for the expression of this cytoskeleton protein in non-neuronal and neuronal cells along rat and human efferent ductules and epididymis (initial segment, caput, and cauda). Reverse transcription/polymerase chain reaction and Western blot analysis were used to confirm the presence of MAP 1B (mRNA and protein) in rat tissues. Immunohistochemical studies revealed MAP-1B–positive staining in columnar ciliated cells present in efferent ductules and in narrow cells located in the initial segment, in both rat and human. MAP-1B–positive basal cells, located underneath the columnar cells, were only identified in the initial segment and caput epididymidis of the rat. Qualitative analysis of tissues from 40–day-old and 120–day–old rats indicated that the number of MAP-1B–positive ciliated, narrow, and basal cells per tubule increased with sexual maturation. These immunoreactive cells did not stain for dopamine β–hydroxylase or acetylcholinesterase, indicating that they were not adrenergic or cholinergic in nature. Immunohistochemical studies also revealed the presence of MAP-1B–positive staining in interstitial nerve fibers in caput and cauda epididymidis from both rat and human. Thus, the expression of MAP 1B is not confined to a specific cell type in rat and human efferent ductules and epididymis. The functional significance of this cytoskeleton protein in tissues from the male reproductive tract requires further investigation.

Neuroendocrine cells are present in the domestic fowl ovary.

Neuroendocrine cells are present in virtually all organs of the vertebrate body; however, it is yet uncertain whether they exist in the ovaries. Previous reports of ovarian neurons and neuron‐like cells in mammals and birds might have resulted from misidentification. The aim of the present work was to determine the identity of neuron‐like cells in immature ovaries of the domestic fowl. Cells immunoreactive to neurofilaments, synaptophysin, and chromogranin‐A, with small, dense‐core secretory granules, were consistently observed throughout the sub‐cortical ovarian medulla and cortical interfollicular stroma. These cells also displayed immunoreactivity for tyrosine, tryptophan and dopamine β‐hydroxylases, as well as to aromatic L‐DOPA decarboxylase, implying their ability to synthesize both catecholamines and indolamines. Our results support the argument that the ovarian cells previously reported as neuron‐like in birds, are neuroendocrine cells.

Mitochondrial impairment induced by 3-nitropropionic acid is enhanced by endogenous metalloprotease activity inhibition in cultured rat striatal neurons.

Metalloproteases from the metzincin family mediate molecule processing at the cell membrane termed ectodomain shedding (ES). This mechanism enables the generation of intracellular and extracellular fragments from cell membrane molecules that exert additional functions involved in cell processes including cell death, beyond those of full length molecules. Micotoxin 3-nitropropionic acid (3-NP) induces striatal neuronal degeneration in vivo and in vitro through mitochondrial complex II inhibition. In this study, we hypothesized that metalloproteases regulate mitochondrial activity in cultured rat striatal neurons undergoing degeneration. To test this idea, striatal neuronal cultures characterized by NeuN and GAD-67 expression were treated with 3-NP together with the metalloprotease inhibitor GM6001 and their mitochondrial activity was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Our results showed that metalloprotease inhibition potentiated mitochondrial activity impairment induced by 3-NP whereas the inhibitor alone had no effect. These results indicate that metalloproteases regulate and promote mitochondrial functionality in striatal neurons undergoing degeneration induced by 3-NP. Since NMDA receptor is involved in the excitotoxic neuronal death triggered by 3-NP and is known to undergo ES, we analyzed NMDAR subunit NR1 phenotypic distribution by immunofluorescence. 3-NP and GM6001 induced abnormal perinuclear NR1 accumulation that was not observed with 3-NP or GM6001 alone. This observation suggests that metalloproteases are involved in NR1 cellular reorganization induced by 3-NP, and that their inhibition results in abnormal NR1 distribution. Together results indicate that endogenous metalloproteases are activated during striatal neurodegeneration induced by 3-NP eliciting an adaptative or compensatory response that protects mitochondrial functionality.