First Exposure of Dark‐reared Rats Colchicine Binding Capacity of to Light Increases Visual Cortex

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Incorporation of [14T]leucine into trichloracetic acid‐precipitable material and tubulin‐enriched fractions, and total tubulin levels as determined by colchicine‐binding activity and retention on DE81 filter discs, were measured in various regions of the chick brain following training on a one‐trial passive avoidance task, suppression of pecking at a chromed bead as a consequence of the aversive taste of methylanthranilate. Radioactive pulse time was 0.5 h. The only brain region in which changes were found was the anterior forebrain roof, the same area in which biochemical changes in response to exposure of the birds to an imprinting stimulus have been observed previously. In the anterior forebrain roof the changes observed as a consequence of training were detectable at 0.5 and 24 h after the 10‐s training experience but not 48 h subsequently. One‐half hour after training, there were increases of the order of 20 or 30% in [14T]leucine incorporation into particulate and postmitochondrial TCA‐precipitable material and a tubulin‐enriched fraction purified as above. There were comparable increases in the total amount of colchicine‐binding activity. By 48 h, none of these increases were detectable. Subcellular fractionation of the particulate fraction showed that most of the increase of incorporation into the tubulin‐enriched fraction and in colchicine‐binding activity was present in the soluble content of the synaptosomes; there were no increases in either measure in the synaptic membrane fraction. The possible role of changed levels and turnover of tubulin in the plastic responses of the brain to learning experiences is discussed.

Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 83%

mentioning

confidence: 93%

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Passive Avoidance Learning Results in Region‐Specific Changes in Concentration of and Incorporation into Colchicine‐Binding Proteins in the Chick Forebrain

Mileusnic

Rose

Tillson

1980

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“…A similar biphasic response to first exposure to light was described by Rose (1967) for incorporation of [3H]lysine into trichloroacetic acid-insoluble material from rat brain. The transient character of changes is often observed in processes occurring as a result of first exposure to light of dark reared animals: an elevation of muscarinic receptor binding (Rose and Stewart, 1978) and colchicine binding capacity (Potempska and Rose, 1980) observed after 3 h long exposure also returns to control values after 24 h of visual experience. Also, two-directional changes of serotonin receptor binding during first exposure to light of rats were described by Murphy et al (1980), an increase in binding observed after 3 h of stimulation.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Changes of Serotonin Levels During the First Visual Experience of Binocularly Deprived Kittens

Kossut

Wójcik

Skangiel-Kramska

1981

Kittens deprived of pattern vision until the 28th day of life received monocular visual experience for 3, 6, 14, and 75 h. Biphasic response of serotonin was found in the visual cortex. Stimulation for 3 h resulted in an increase of serotonin level whereas at 14 h it produced a decrease. The effects are transient, no longer observable after 75 h stimulation. No changes were observed in somatosensory cortex.

“…Our interest in tubulin derives from the observation that in other sensory stimulation and learning experiments in our laboratory, modulationof incorporation of precursors into, and of total amounl of, tubulin have been shown to occur Stewart and Rose, 1978;Potempska and Rose, 1980;Mileusnic et al, 1980). A preliminary report of part of the work reported here has already been published (Longstaff and Rose, 1978).…”

mentioning

confidence: 90%

Ontogenetic and Imprinting‐Induced Changes in Chick Brain Protein Metabolism and Muscarinic Receptor Binding Activity

Longstaff

Rose

1981

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Over the 20-min period following exposure of young chicks to a flashing light as an imprinting stimulus there is an increased incorporation of [14C]leucine into an acidic (tubulin-enriched) protein fraction of the anterior dorsal forebrain in birds which have learnt the characteristics of the stimulus as compared with, either birds which have been exposed to an imprinting stimulus but learn poorly, or chicks kept in the dark. This brain region has been implicated in several studies as the locus for a number of biochemical modulations that accompany learning. The amount of [14C]leucine incorporated does not seem to be determined by precursor pool availability; it does, however, correlate with a well-validated measure of the extent to which birds have learnt to recognise the characteristics of the stimulus, as shown by a two-choice discrimination test. There is no change in the total content of tubulin dimer as assayed by colchicine binding under these conditions. Additionally, in birds which show evidence of learning, the binding of quinuclidinyl benzilate, an irreversible muscarinic ligand, is altered in both the posterior dorsal forebrain and midbrain regions. None of these effects could be simply the result of visual stimulation. The meaning of these changes is discussed.