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E C Azmitia

Publications and source records attributed to E C Azmitia.

135 records · Page 8Linked to original sources
PubMedDate not supplied

Neonatal ACTH and corticosterone alter hypothalamic monoamine innervation and reproductive parameters in the female rat.

Female Sprague-Dawley rat pups were injected SC with either ACTH(1-24) (0.5 mg/kg) or saline vehicle once daily from postnatal day 1 (day of birth) to day 7. Plasma corticosterone (CORT) levels were recorded via radioimmunoassay (RIA) on day 4 to measure adrenal response to these treatments. Hypothalamic 5-HT and DA fiber densities were assessed using high-affinity specific 3H-5-HT and 3H-DA uptake at days 7, 25, and at adulthood (80-90 days). Animals were checked daily for vaginal opening (starting on day 30) as a sign of sexual maturation and later tested for sexual behavior as virgins (60-70 days of age). Plasma estradiol and progesterone levels were measured via RIA. Plasma CORT levels were greatly increased among ACTH-treated animals during the treatment period. The 5-HT uptake was significantly increased in ACTH-treated animals at day 7 (p < 0.01) and at adulthood (p < 0.02) compared to controls. The DA uptake was significantly higher among ACTH-treated animals at day 7 (p < 0.01). The sexual maturation of ACTH-treated animals was delayed when compared to control animals (p < 0.01). The ACTH-treated animals displayed slight deficits in female sexual behavior compared to control animals (p < 0.05). No significant changes in plasma sex steroid levels were found. Based on this study, we suggest that monoamine innervation into the developing female hypothalamus is susceptible to early postnatal manipulation with ACTH and CORT, and that the resulting changes in these monoamine fiber densities may be responsible for the observed deficits in reproductive maturation and behavior.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Rapid neurotrophic actions of an ACTH/MSH(4-9) analogue after nigrostriatal 6-OHDA lesioning.

ACTH peptide fragments demonstrate potent neurotrophic effects on peripheral nerves in situ, central neurons in culture, and have been implicated to have effects on central neurons in vivo. Neurotoxic lesioning of the nigrostriatal system, which depletes the striatum of dopamine, provides a feasible model of central regeneration in which to test these peptides. Male Sprague-Dawley rats were lesioned unilaterally with 6-hydroxydopamine (8 micrograms/4 microliters), infused into the substantia nigra. They were subsequently treated with 10 micrograms/kg IP of Org 2766 [ACTH/MSH(4-9) analogue] or saline every 24 h starting immediately after the infusion and were observed for 2 weeks. Rotational behavior data indicate that Org 2766 significantly decreases ipsiversive turning (p < 0.05), induced by amphetamine (2 mg/kg), as well as accelerating the onset of denervation supersensitivity induced by apomorphine (0.05 mg/kg). Evaluation of dopamine immunohistochemistry, using an anti-tyrosine hydroxylase antibody, demonstrates an enhanced intensity of staining in the ORG 2766-treated tissue compared to its saline counterpart. This difference is confirmed and quantified through specific high-affinity dopamine uptake. Dopamine uptake is about 17% higher in the striata of animals treated with Org 2766. Higher dopamine uptake levels in these ACTH-treated animals correlate with greater fiber density in this group. Therefore, it appears that treatment with the ACTH/MSH(4-9) analogue Org 2766 (10 micrograms/kg/24 h) offers a protective effect from 6-OHDA lesions in the substantia nigra as well as accelerating various compensatory mechanisms involved in functional recovery.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Antipeptide antibodies against the 5-HT1A receptor.

The availability of the primary amino acid sequence for a large number of molecules provides a fruitful opportunity for their cellular localization by utilizing the procedure of antipeptide antibody formation. This procedure permits a synthetic peptide sequence to be attached to a carrier molecule for the purpose of inoculating an animal to raise specific antibodies against the selected protein sequence. In this report we describe a number of steps that can be taken to increase the likelihood that the selected peptide sequence will be specific and antigenic. In addition, we describe how the peptides are synthesized, purified and coupled to keyhold limpet hemocyanin. The preparation of the antibody and its characterization are also presented in this method report. The immunocytochemical staining at both the light and ultrastructural level with serotonin (5-HT1A) receptor antipeptide antibodies is discussed. The advantages and disadvantages of this procedure are summarized.

Amino Acid Sequence↗
PubMedDate not supplied

Use of tissue culture models to study neuronal regulatory trophic and toxic factors in the aged brain.

Dementia is believed to result from the loss of selective neurons within the brain, but approaches for systematic study of that degenerative process are hampered by the complexity of the neuronal milieu. Tissue culture models provide a means to reduce dramatically the variables inherent in the study of neuronal plasticity. Three levels of complexity can be described: cellular and molecular diversity; primary and secondary interconnections; and finally, the dynamics influenced by age. The following review discusses the advantages and disadvantages of tissue culture models for the detailed study of neuronal trophic and toxic factors. Our selection of factors is broadened to include ions, intermediate metabolites, antioxidants, steroids, neuropeptides, gangliosides, metals, neurotransmitters, brain extracts, and protein molecules. Most of these factors have been shown to be altered in the aged brain, to have a significant effect on cultured neurons, or both. This multilevel analysis provides the reader with an overview of the events regulating neuronal survival, differentiation and death. An understanding of these basic questions is necessary to sequence the molecular events resulting in neuronal death.

Aging↗
PubMedDate not supplied

Recent advances in serotonin research. II: Polymerase chain reaction to positron emission tomography.

This issue contains the method-oriented papers from an interdisciplinary conference held at the Serotonin Club meeting in New Orleans. The techniques are described in detail with attention given to making the 'tricks-of-the-trade' known to the reader. This short review compares these methods to those presented at the first 'Advances in Serotonin Research' meeting in Los Angeles in 1981. The emerging dominance of molecular biology and pharmacology in serotonin research is reflected by this collection of papers. The strong interdisciplinary nature of these new methods, their greater sensitivity and selectivity and their application to human material makes the distance between polymerase chain reaction and positron emission tomography appear trivial.

Animals↗
PubMedDate not supplied

Laminin facilitates and guides fiber growth of transplanted neurons in adult brain.

Laminin has been shown in vitro to act as a surface adhesive molecule for neuronal process elongation. To test whether laminin has a similar role in the brain, we sequentially injected laminin and transplanted fetal neurons into various brain regions to determine if the fetal neurons would preferentially grow along a laminin injection tract. In the fetal brain, the raphe area of the rostral rhombencephalon is rich in serotonergic (5-HT) neurons; the rostral ventral mesencephalon is rich in dopamine (DA) neurons, while the lateral rhombencephalon is rich in norepinephrinergic (NE) neurons. These three areas were transplanted to the motor cortex, neostriatum or hippocampus of adult animals. The tract used for microinjection of cell suspension was then immediately filled with laminin in a suspension media or a laminin-collagen (type IV) mixture. In other animals, laminin or control solution was injected in a separate needle tract displaced 0.3-1 mm from the transplant injection tract. Straight and thick 5-HT, DA or NE immunoreactive (IR) fibers (stained with anti-5-HT or anti-tyrosine hydroxylase antiserum) were predominant within the laminin-treated tracts, or were directed toward the laminin-treated parallel tracts when it was positioned less than 0.5 mm from the transplant site. The density of 5-HT-, DA- and NE-IR fibers in the injection tracts in all three brain areas was much higher for laminin and laminin-collagen mixture than control media. Thin axonal fibers of fetal 5-HT and NE neurons were observed surrounding the laminin-treated tracts, but not around vehicle-injected tracts. In addition, a number of transplanted 5-HT, DA and NE neuronal cell bodies were seen within the laminin-treated tracts, but not in vehicle-treated tracts. Finally, laminin injection to the hippocampus, motor cortex or neostriatum of the adult brain did not stimulate sprouting of undamaged adult 5-HT or NE fibers. These results suggest that purified laminin can facilitate and guide process outgrowth of 5-HT, DA and NE neurons during early developmental stage, but does not induce sprouting on these same fiber types in the adult brain.

Animals↗