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C A Watson

Publications and source records attributed to C A Watson.

7 recordsLinked to original sources
PubMed1991

Infra-additivity of combined treatments with selective D1 and D2 receptor antagonists for inhibiting sucrose reinforcement.

Selective antagonists of either the D1 receptor (SCH 23390) or of the D2 receptor (raclopride) produce a dose-related inhibition of sucrose sham feeding in the rat. We investigated the effect of combined treatments with these antagonists on sucrose sham feeding and observed infra-additivity of inhibition across a range of doses. On the basis of this observed occlusive relationship, we conclude that the relevant D1 and D2 receptor mechanisms mediating sweet taste reward do not function independently.

Animals↗
PubMed1990

Similar effect of raclopride and reduced sucrose concentration on the microstructure of sucrose sham feeding.

Raclopride, a dopamine D2 antagonist, decreases the intake of sucrose solutions during sham feeding tests and of water during sham drinking tests in rats. To determine whether the reduced intake of sucrose by raclopride was due to a decrease in the positive reinforcing effect of sucrose or to an impairment in licking movements, we compared the rate, efficiency and pattern of licking after two procedures each of which decreased sucrose sham intake about 50%; these were (a) pretreatment with raclopride (ID50), and (b) dilution of the sucrose concentration sham fed from 10 to 5%. Microstructural analysis failed to reveal significant differences in the rate, efficiency (licks/ml) or patterns of licking between these two procedures. When raclopride inhibited the sham drinking of water, the rate and efficiency of licking were normal, but the patterns of licking were qualitatively different from those observed when raclopride inhibited the sham feeding of sucrose. We conclude that raclopride decreases intake of 10% sucrose during sham feeding and intake of water during sham drinking by decreasing the positive reinforcing potency of the orosensory effect(s) of the two liquids on licking rather than by decreasing the ability to lick. These results provide strong evidence that interaction of dopamine at D2 receptors is necessary for the normal sensory and/or hedonic processing of the orosensory stimuli produced by sucrose during sham feeding and by water during sham drinking.

Animals↗
PubMed1990

Maternal messenger RNA distribution in silkmoth eggs. I. Clone Ec4B is associated with the cortical cytoskeleton.

We have constructed a cDNA library from mature egg RNA of the silkmoth, Hyalophora cecropia. Differential screening of the library using cDNA made against mRNAs from the yolky cytoplasm (soluble fraction) and the cortical cytoplasm (cytoskeletal-associated or cortical fraction) resulted in several clones that hybridized to a higher degree to the cDNA from the cytoskeletal-associated fraction. We selected and analyzed the clone giving the strongest signal (designated Ec4b) for its distribution in situ and found that it bound to mRNAs in the nurse cell cytoplasm, in the cortex and in the follicle cells of oocytes. Hybridization of the insert from Ec4b to both detergent-soluble and -insoluble (cortical) RNA on dot blots further supported the observation that the mRNA corresponding to Ec4b was enriched in this cytoskeletal fraction. The mRNA for Ec4b was approximately 500 bases long and the gene seems to be a member of a large multigene family in the H. cecropia genome. Analyses of the nucleotide and amino acid sequences reveal similarity to lepidopteran chorion genes and a lesser but convincing similarity to vertebrate cytokeratins. The filter and in situ hybridization data point to the association of specific messenger RNAs with the cortical cytoskeleton of silkmoth oocytes. Aspects of the structure of the protein encoded by this mRNA suggest that it is a structural component necessary for formation of the cellular blastoderm of the embryo. The association of this maternal mRNA with the cortical cytoskeleton presents the interesting possibility that mRNA bound to the cytoskeleton may be capable of participating in the synthesis of new cytoskeleton or related structures during blastoderm formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗