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Biomedical subjects

C A Sandman

Publications and source records attributed to C A Sandman.

At least 109 records · Page 6Linked to original sources
PubMed1977

An analog of enkephalin having prolonged opiate-like effects in vivo.

Intraventricular administration of the enkephalin analog, [D-Ala2]-metenkephalin, induces profound and long-lasting analgesia, as well as other opiate-like behavioral effects in the rat. This analgesia was highly dose dependent, of much greater magnitude, and about 30 times longer lasting than that produced by the naturally occurring peptide, methionine-enkephalin. The behavioral effects of the [D-Ala2] analog could be completely reversed by the opiate antagonist, naloxone, suggesting that these effects were mediated by opiate receptors. Systemic administration of naloxone alone resulted in a significant increase in pain sensitivity. These findings support the view that endogenous opiate systems may play an important role in modulating pain sensitivity.

Animals↗
PubMed1977

Endorphin analogs with potent and long-lasting analgesic effects.

The analgesic effects of intracerebroventricular administration of alpha, gamma, and beta-endorphin and their D-Ala2-analogs were examined in the rat using the tail-flick test. Analgesia was produced by all substances. The actions of D-Ala2-alpha and -beta-endorphin were considerably greater than the parent forms, whereas D-Ala2-gamma-endorphin was approximately equivalent to the parent compound. The marked analgesia was dose dependent and prolonged for all analogs. Since these effects were reversed by the opiate antagonist naloxone, it was concluded that opiate receptors mediate the action of these analogs. It is suggested that these analogs may be useful in behavioral tests when a longer duration of action is desirable.

Analgesics↗
PubMed1977

Heart rate and cardiac phase influences on visual perception.

Twenty-six subjects were tested with a tachistoscopic recognition task while heart rate and several other autonomic indexes were monitored. In Experiment 1, heart rate was employed as an independent variable, and stimulus presentation was contingent upon the presence of individually determined low, middle, and high heart rates. The results indicated that low heart rate facilitated performance especially for stimuli presented at the fastest exposure. In Experiment 2, stimulus presentation was dependent upon cardiac phase. The findings indicated that stimulus recognition was enhanced during the cardiac P wave, but the effect was apparent only during the fastest exposure. Multiple regression analyses of the individual subject's data during both experiments indicated that highly idiosyncratic patterns of physiological responses predicted perceptual performance. The results were interpreted as being consistent with the formulations of the Laceys and also suggested that cerebral perfusion be considered as a relevant determinant of behavior.

Adult↗
PubMed1977

MSH/ACTH 4-10 influences behavioral and physiological measures of attention.

Eleven healthy male volunteers were infused with MSH/ACTH 4-10 and a control solution in a completely crossed and balanced procedure. Perception, attention and memory were tested as were heart rate and cephalic pulse amplitude in response to changes in the environment. Treatment of subjects with MSH/ACTH 4-10 raised their perceptual threshold for detection of simple stimuli and facilitated perceptual integration of patterned information. Administration of the heptapeptide improved the subjects' ability to discriminate tests of relevant from irrelevant information and augmented the heart-rate deceleratory response during presentation of novel stimuli. It was speculated that MSH/ACTH 4-10 has a predominant influence on attentional processes and that it may be uniquely coded for attentional/perceptual functioning.

Adrenocorticotropic Hormone↗
PubMed1977

CNS and pituitary effects of hypothalamic peptides and MSH.

The first part of this essay discussed the CNS effects of the pituitary peptide MSH. These investigations anticipated studies of the CNS effects of peptides found in the hypothalamus which were discussed in the second part of the essay. Some of the endocrine actions of the hypothalamic peptides upon the release of pituitary hormones were discussed in the last part of the essay. Together, the CNS and pituitary effects of hypothalamic peptides and MSH provide intriguing examples of areas of investigation which can be expected to be greatly expanded in the future.

Adrenocorticotropic Hormone↗
PubMed1976

Effects of neonatal cerebral ventricular injection of ACTH 4-9 and subsequent adult injections on learning in male and female albino rats.

An investigation of permanent developmental effects of a potent, long acting ACTH/MSH 4-10 analogue (Organon 2766) on adult passive avoidance performance and of subsequent peripheral adult injections of the same substance on visual (black and white) discrimination learning and reversal in a Thompson-Bryant box was conducted. A subproblem analysis of visual and position preferences during reversal was performed. No differences in passive avoidance performance or in original discrimination learning were obtained. Both infant and adult treatments enhanced reversal learning and visual orientation (proportion of responese to the previously positive stimulus). Infant treatment suppressed position orientation in males and enhanced position orientation in females. These effects were interpreted as indicating that ACTH-like peptides enhance attention to the relevant stimulus by a direct effect on the brain.

Adrenocorticotropic Hormone↗
PubMed1976

Influence of three short-chain peptides (alpha-MSH, MSH/ACTH 4-10, MIF-I on) dimensional attention.

Male, albino rats were treated with alpha-MSH, MSH/ACTH 4-10, MIF-I or a diluent control solution and then tested on a visual discrimination problem. Immediately after acquistion of the visual task the animals were tested with a spatial extradimensional shift problem. The animals treated with the MSH/ACTH 4-10 and MIF-I acquired the discrimination nonsignificantly faster than animals treated with alpha-MSH or a placebo. A subproblem analysis of the EDS behavior indicated that the peptides significantly improved performance probably by affecting attention.

Adrenocorticotropic Hormone↗
PubMed1976

Neuropeptide MSH/ACTH 4-10 enhances attention in the mentally retarded.

Twenty adult mentally retarded men were randomly assigned to receive MSH/ACTH 4-10 or a vehicle control solution in a double blind procedure. After an intravenous injection the subjects were presented with an orienting sequence and a series of behavioral tests. Treatment with the peptide resulted in a significant decelerative heart rate response during the test stimulus of the orienting sequence. Improved performance of the intradimensional and extradimensional shift of a visual discrimination procedure was significant for subjects receiving MSH/ACTH 4-10. The pattern of response on the subproblem analysis of the extradimensional shift reflected greater dimensional attention in the subjects treated with the peptide. Attentive subjects given MSH/ACTH 4-10 evidenced significant improvement on a rhythm matching test, a test of spatial localization and a visual retention test. The data were interpreted as indicating that the peptide resulted in improved attention of stimulus processing. It was speculated that MSH/ACTH 4-10 may be unquely coded for perceptor/attentional functioning and may be useful as a treatment for disorders of attention.

Adrenocorticotropic Hormone↗
PubMed1976

Hormones and regional brain blood flow.

Acute effects of the hormones, estradiol-17beta and alphaMSH, and of neonatal pretreatment with alphaMSH on the flow of blood to regions of the brains of conscious adult rats have been determined with an indicator distribution technique. As previously reported, flows were reduced in most areas within 10 min after intravenous administration of alphaMSH; only the occipital cortex was spared. Though these effects were transitroy for most areas, perfusion of pons and medulla, cerebellum, hippocampus and parietal cortex was still low by 20 min. However, pretreatment with alphaMSH during infancy led to persistent behavioral changes which were not accompanied by flow differences. Assuming that flow changes reflect functional changes, the rapid responses to alphaMSH suggest an explanation for the effects of this hormone on visual learning and on the determination of subsequent learning behavior. By contrast, estradiol, within 10 min after injection, increased flow to most regions of the brain, especially the frontal cortex, hippocampus, basal ganglia and cerebellum; females were more affected than males. Flow changes were greater than those elicited by more obvious behavior-modifying drugs. Compared to alphaMSH, the flow data for estradiol suggest a physiologic basis for a behavioral effect which is likely to be different yet, perhaps, equally profound.

Animals↗
PubMed1976

Operant autonomic conditioning and rod-and-frame test performance.

Forty subjects were administered the portable rod-and-frame test (RFT) before and after operant autonomic conditioning training or control experiences. Ten subjects were assigned to each of four groups: a heart rate conditioning group; a false heart rate feedback group; a galvanic skin-response conditioning group; and a control group. Half of the subjects in the three experimental groups were informed of the response-reinforcement contingencies, and half were not informed. Informed subjects in the conditioning groups exhibited significantly lower portable RFT scores after conditioning. The results suggest that awareness of and control over autonomic functioning may be an important determinant of RFT performance.

Adult↗
PubMed1976

Some questions related to melanocyte-stimulating hormone.

A number of questions remain unsettled about the release of melanocyte-stimulating hormone (MSH) and about its function. Even though relatively few investigators are studying this area, some generalities have emerged during the last 10 years. It now seems that release of MSH from the pituitary is inhibited by a substance present in the hypothalamus. The structure of this physiologic inhibitor of MSH release may still not be considered an established entity but there is evidence for additional mechanisms capable of exerting a fine control on the release of MSH. Contrary to some opinions, the release of MSH does not always occur together with the release of ACTH, and the release of the two hormones can be dissociated in several laboratory and clinical situations. In addition, many studies have shown that the pituitary peptide, MSH, exerts behavioral and electroencephalographic effects in both the rat and man. The hypothalamic peptide Pro-Leu-Gly-NH2 (MIF-I) also has direct effects on the central nervous system that may include alleviation of the symptoms of Parkinson's disease.

Animals↗
PubMed1975

Enhancement of attention in man with ACTH/MSH 4-10.

Normal men were infused for 4 hr with ACTH/MSH 4-10 or a control solution. Behavioral testing after the infusion indicated that subjects who received ACTH/MSH 4-10 were less anxious and had better visual memory than control subjects but the predominant effect of the heptapeptide was to increase visual attention. It was speculated that ACTH/MSH 4-10 may be uniquely coded for attentional functioning.

Adrenocorticotropic Hormone↗