Biomedical subjects

R F Lane

Publications and source records attributed to R F Lane.

29 records · Page 2Linked to original sources

PubMed1984

A comparison of CNS stimulants with phencyclidine on dopamine release using in vivo voltammetry.

Phencyclidine (PCP) produces some neurochemical and behavioral effects in rats similar to those produced by the indirectly acting dopamine (DA) agonists amphetamine and amfonelic acid. In view of these findings, the effects of PCP, d-amphetamine and amfonelic acid on the release of DA in the rat striatum were examined by in vivo voltammetry. Drug effects on DA release were determined using newly developed electrodes selective for catecholamines. PCP (5 and 10 mg/kg IP) produced a dose-dependent decrease in the electrochemical signal that lasted for approximately 4 hr. In contrast, d-amphetamine (2.5 mg/kg, IP) and amfonelic acid (5.0 mg/kg, IP) both caused marked increases in electrochemical signals. The data provide evidence that PCP at the doses tested alters dopaminergic neurotransmission in a manner different from that of amphetamine and the non-amphetamine central nervous system stimulants by decreasing DA release from dopaminergic nerve terminals.

Animals↗

PubMed1983

Daily rhythms of serotonin metabolism in the medial hypothalamus of the chicken: effects of pinealectomy and exogenous melatonin.

Indoleamine levels in punches of the medial hypothalamus containing the suprachiasmatic nuclei (SCN) of 4-week-old cockerels were determined by HPLC-EC. Melatonin levels in punches were determined by radioimmunoassay (RIA). Daily rhythms of serotonin (5-HT) and of its metabolite 5-hydroxy-3-indoleacetic acid (5-HIAA) were observed; levels were higher at midnight than at midday. A daily rhythm with the same phase in punch melatonin content was also observed. Pinealectomy at 1 week after hatching abolished the 5-HIAA and melatonin rhythm in 4-week-old birds but did not abolish the 5-HT rhythm. Injections of melatonin (0.5 mg/kg) increased 5-HT, 5-HIAA and melatonin levels in the hypothalamic punches. These results indicate that circulating melatonin of pineal origin may act to increase 5-HT turnover and/or release in the SCN. They suggest a link between the circadian secretion of pineal melatonin and the regulation of 5-HT projections to the hypothalamus from the raphe nuclei in the brainstem of the chicken. We have previously shown that the rhythmic secretion of melatonin by the pineal is influenced by oscillators in the brain via the superior cervical ganglia. The results reported here indicate that melatonin in turn may regulate brain oscillators, suggesting a neuroendocrine loop within the avian circadian system.

Animals↗

PubMed1983

In vivo electrochemical evidence for an enkephalinergic modulation underlying stereotyped behavior: reversibility by naloxone.

The effect of the enkephalin pentapeptide analog (WY 42,896) on amphetamine-induced stereotypy was studied in male, albino rats. WY 42,896 significantly inhibited amphetamine-induced stereotypy. The inhibition of the head-bobbing and sniffing components was significantly reversed by naloxone. Disinhibition of the rearing components by naloxone reached borderline significance. In vivo electrochemical measurements in rat caudate showed that WY 42,896 inhibited both basal and amphetamine-induced dopamine release. This inhibition was prevented by naloxone. These data show an enkephalinergic-dopaminergic interaction in rat striatum, both behaviorally and biochemically, and suggest a presynaptic site of action of the enkephalin on dopamine neurons.

Animals↗

PubMed1983

Chemically modified electrode for in vivo monitoring of brain catecholamines.

A chemically modified graphite paste electrode was developed to allow catecholamines to be electrochemically distinguished from ascorbic acid and the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). Interference from 5-hydroxyindoles is eliminated through appropriate choice of electrode potential. The electrode gives linear current responses with increasing concentrations of catecholamines unaffected by the presence of ascorbic acid or DOPAC and exhibits long-term response stability in brain tissue. Examples are provided demonstrating the selectivity of the electrode to changes in extracellular dopamine in the rat striatum.

Animals↗

PubMed1982

Normal rats trained to circle show asymmetric caudate dopamine release.

Caudate catecholamine release was monitored by bilateral in vivo electrochemical electrodes in male Sprague-Dawley rats trained to circle for sucrose/water reward. Baseline release of dopamine was equal from both sides of caudate. When reinforced circling began, 44 +/- 4 percent greater catechol release occurred from the caudate contralateral to the circling direction. As turning subsided, differential release returned to basal levels. Further evidence that the catecholamine metabolism was affected by turning was obtained by direct measurement of caudate dopamine and DOPAC at selected time points. Concentration data showed relative increases in dopamine and DOPAC in the contralateral caudate. These data provide evidence that dopamine is released asymmetrically from caudate in unlesioned rats during voluntary behavior.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1976