Segregation of FMRF amide-immunoreactive efferent fibers from NPY-immunoreactive amacrine cells in goldfish retina.

Immunocytochemical studies were conducted on goldfish to determine whether a retinal efferent fiber system, immunoreactive to the tetrapeptide Phe-Met-Arg-Phe-NH2 (FMRFamide), might contain instead a substance similar to one of the 36-amino acid pancreatic polypeptides, the C-terminus of which is similar to FMRFamide. Our results demonstrate the presence of two separate peptidergic systems, one containing FMRFamide-like, and the other pancreatic polypeptide-like peptides. Antisera to FMRF amide reveal the efferent fibers, whose axons exit the optic nerve and terminate in layer 1 of the inner plexiform layer, as previously described. Antisera to porcine neuropeptide Y, and to avian and bovine pancreatic polypeptides label a sparse population of putative amacrine cell bodies and a dense fiber plexus in layers 1, 3, and 5 of the inner plexiform layer. Based on intensity of staining, this amacrine cell peptide appears to be most similar to neuropeptide-Y. Radioimmunoassay and immunocytochemical staining of retinas in which the efferent fiber peptide was depleted by optic nerve crush confirm in large part the observation that the two peptide systems are distinct. However, there is some cross-recognition of the FMRF amide-like tissue antigen by pancreatic polypeptide antibodies. Double-label studies with antisera to tyrosine hydroxylase and neuropeptide-Y indicate that the pancreatic polypeptide antigen is not co-localized with catecholamines.

Evidence for FMRF-amide as a neurotransmitter in the gill of Aplysia californica.

In Aplysia californica, multiple regulatory mechanisms are involved in the actions of neurotransmitters on the gill. Neurotransmitter receptors and adenylate cyclase were examined in a particulate fraction of gill homogenates. The neuropeptide FMRF-amide stimulated enzyme activity 7- to 8-fold (EC50, 1 microM) via receptors that were pharmacologically distinct from those for dopamine and serotonin. FMRF-amide augmented cyclic AMP levels in slices of gill tissue with a time course similar to that for adenylate cyclase activation. Increases in cyclic AMP levels produced by the neuropeptide were potentiated by the phosphodiesterase inhibitor theophylline. Physiological responses to neuropeptides and cyclic AMP analogues were examined in a perfused, isolated gill preparation. Phasic contractions evoked by FMRF-amide (EC50, 0.1 microM) were mimicked by membrane-permeable analogues of cyclic AMP. Comparison of FMRF-amide effects on adenylate cyclase and gill behavior suggests an association between cyclic AMP and phasic contractions. In addition, FMRF-amide-like immunoreactivity, detected by antisera raised against the neuropeptide, was found in nerve fibers innervating the gill. These findings indicate that in Aplysia, FMRF-amide or a closely related peptide neurotransmitter may be involved in the physiological regulation of gill behavior.

The goldfish nervus terminalis: a luteinizing hormone-releasing hormone and molluscan cardioexcitatory peptide immunoreactive olfactoretinal pathway.

Antisera to two putative neurotransmitters, luteinizing hormone-releasing hormone (LHRH) and molluscan cardioexcitatory tetrapeptide (H-Phe-Met-Arg-Phe-NH2; FMRF-amide), bind specifically to neurites in the inner nuclear and inner plexiform layers of the goldfish retina. Retrograde labeling showed that intraocular axon terminals originate from the nervus terminalis, whose cell bodies are located in the olfactory nerves. Double immunocytochemical and retrograde labeling showed that some terminalis neurons project to the retina; others may project only within the brain. All terminalis neurons having proven retinal projections were both LHRH- and FMRF-amide-immunoreactive. The activity of retinal ganglion cells was recorded with microelectrodes in isolated superfused goldfish retinas. In ON- and OFF-center double-color-opponent cells, micromolar FMRF-amide and salmon brain gonadotropin-releasing factor ( [Trp7, Leu8] LHRH) caused increased spontaneous activity in the dark, loss of light-induced inhibition, and increased incidence of light-entrained pulsatile response. The nervus terminalis is therefore a putatively peptidergic retinopetal projection. Sex-related olfactory stimuli may act through it, thereby modulating the output of ganglion cells responsive to color contrast.

Studies on the mechanism of action of alpha-monochlorohydrin.

After a single oral dose of 100 mg/kg of alpha-chlorohydrine, two distinct phases in the response of the testes to the treatment have been observed: (i) the immediate onset of testicular swelling lasting up to five days, accompanied with a steady increase in the weight of the testes and (ii) thereafter a constant decrease in the testes weight. Changes in the diameter of the seminiferous tubules and the thickness of the basement membrane were observed after the administration of the drug. Multinucleated giant cells were encountered 5 days after drug administration. Alkaline phosphatase, SDH, nucleic acids and proteins showed a fall after treatment with the drug. On the contrary, cholesterol, phospholipids and glycogen showed an increase after its administration. Acid phosphatase showed a fall in the initial stages only, but the activity was higher after 10, 20 and 40 days of the treatment with the drug. The level of plasma and testes testosterone remained normal after chlorohydrin administration. The induction of lesions in hypophysectomised gonadotropin-stimulated animals suggests that the action of chlorohydrin is not mediated through gonadotropins. Alpha-chlorohydrin administered intratesticularly did not evoke any changes in the histo-architecture of the testis.

Sequential histopathological and biochemical events in rat caput epididymis after alpha monochlorohydrin administration.

This paper presents sequential histological, histochemical and biochemical changes in rat caput epididymis after a single 100 mg/kg oral dose of alpha chlorohydrin. Desquamation of caput epithelium occurs as early as two days after drug treatment. The caput epididymis is blocked because of accumulation of testicular fluid containing exfoliated immature testicular cells and caput epithelium. There was no effect of drug on motility and morphology of spermatozoa examined from different segments of epididymis and vas deferens. Marked decrease in acid and alkaline phosphatases, nucleic acids and proteins have been registered after drug treatment. On the contrary increase in SDH, cholesterol and glycogen was observed after drug treatment. Decrease in phospholipids in initial stages has also been observed.

PIP: The histological, histochemical, and biochemical effects of a single 100 mg/kg oral dose of alpha-chlorohydrin on the caput epididymis of the rat were studied. Within 2 days of treatment, evidence of desquamation of the caput epithelium became apparent. The accumulation of testicular fluid, which contained exfoliated immature testicular cells and caput epithelium, caused blockage of the caput epididymis. However, spermatoz oa recovered from different regions of the epididymis and vas deferens did not exhibit altered motility or morphology. The treatment was associated with a decrease in caput epididymal content of acid alkaline phosphatases, nucleic acids and proteins, and an increase in SDH, cholesterol, and glycogen. Phospholipids were also decreased during the early stages after treatment. The results are discussed in relation to previous explanations of the mechanism of action of alpha-chlorohydrin.