Morphological changes produced by drugs acting on the autonomic nervous system

Depression of endothelial nitric oxide synthase but increased expression of endothelin-1 immunoreactivity in rat thoracic aortic endothelium associated with long-term, but not short-term, sympathectomy

Recent pharmacological studies have shown that perivascular nerves can influence the development and function of vascular endothelial cells (ECs). However, morphological studies have not yet been carried out to investigate whether these functional changes are associated with changes in vasoactive substances in ECs. We used postembedding electron microscopy (EM) triple gold-labeling immunocytochemistry to study the effects of short-term sympathectomy (3 days after 6-hydroxydopamine [6-OHDA] treatment) and long-term sympathectomy (guanethidine and 8 days after 6-OHDA) on the distribution of vasoactive substances in ECs of the rat thoracic aorta. The post-embedding immunocytochemistry, which can detect levels of label in individual cells, showed that there was a significant decrease in endothelial NO synthase (NOS3)-labeled, serotonin (5-HT)-labeled, and substance P (SP)-labeled, but a significant increase in endothelin-1 (ET-1)-labeled, gold particles in ECs after long-term, but not after short-term (3-day), sympathectomy. In conclusion, our results show that long-term sympathectomy causes an increase in ET-1 and decrease in NOS3, 5-HT, and SP immunoreactivity in ECs of the thoracic aorta. Our data also indicate that postembedding EM triple gold-labeling immunocytochemistry is a valuable technique for quantitative studies of the content of vasoactive substances in ECs.

Adrenergic mechanisms of the contractile response of rabbit oviduct to electrical stimulation

1. In rabbit oviduct electrical field stimulation evoked contraction in mature animals and contraction followed by relaxation in juvenile animals. 2. Phentolamine (1 microM) inhibited the contraction. The relaxation was partly suppressed by propranolol (1-10 microM) and completely inhibited by guanethidine (5 microM). 3. Cocaine (1 microM) increased the duration or the amplitude of contractions and abolished or did not change the relaxation. The contraction-increasing effect of cocaine was more pronounced in estradiol-treated mature rabbit. 4. It is concluded that electrically evoked responses in rabbit oviduct are mediated by transmitters released from adrenergic terminals and that estradiol increases neuronal uptake of noradrenaline.

Specific lysis by 6-hydroxydopamine of catecholaminergic synaptosomes prepared from rat cerebrum

The toxicity of 6-hydroxydopamine on synaptosomes prepared from rat cerebra was investigated. The drug caused synaptolysis, and the lytic effect was specific to catecholaminergic synaptosomes, since no neurotransmitters (serotonin and amino acids) other than catecholamines (dopamine and noradrenaline) were liberated by the drug.

Review lecture. Neurotransmitters and trophic factors in the autonomic nervous system

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