To explore the interaction potential of phospholipids, we have studied the hydration of diacyl phosphatidylcholine (PC) and methylphosphocholine (MePC), a pertinent model compound, by ir spectroscopy. Related ab initio Hartree-Fock calculations were performed for MePC. Water is considered ideal as a relevant probe molecule. Spectroscopic data for MePC reveal a strong influence of bound hydration water not only on the phosphate groups but also onto the putatively apolar CH(n) groups. The same could be demonstrated for deuterated dimyristoyl PC taken as a "complete" lipid molecule: both headgroup methyl and methylene moieties are gradually, but remarkably affected by hydration, as evidenced by strong wavenumber upshifts of C-H stretching vibration bands. These findings may originate in directed interactions of the CH(n) groups with bound water molecules, but hydration-driven conformational changes of PC headgroups could also occur. The results of the ab initio calculations rationalize the first explanation by predicting a substantial contribution of specific C-H...OH(2) interactions, mainly characterized by a dramatic loss of electron density of the sigma* antibonding molecular orbitals of C-H bonds. Hence, the propensity of the lipid headgroup methyl and methylene groups to act as donor sites in hydrogen bonding must no longer be ignored when considering the interaction potential of PCs.

Biopolymers↗

PubMedDate not supplied

Elimination of granular cells after intrahippocampal colchicine injection causing disappearance of evoked potentials and deterioration of development of the conditioned avoidance reflex in rats.

The aim of our work was to study the involvement, in the process of learning, of synapses between the perforant path and granular cells of the hippocampal dentate fascia for formation of a conditioned reflex (CR) of active avoidance elaborated in response to electrostimulation of the perforant path. To achieve this we used the property of the neurotoxin colchicine at a certain concentration of eliminating selectively the fascia cells. One month after colchicine injection we observed destruction of granular cells, disappearance of the dentate fascia focally evoked potentials, and considerable deterioration in the elaboration of active avoidance CR. Administration of saline solution in control experiments did not bring about such changes. The results obtained show the important role of the entorhinal input into the hippocampus in the learning model used.

Action Potentials↗

PubMedDate not supplied

Incorporation of 3H-leucine into brain cells after learning.

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Animals↗

PubMedDate not supplied

[Switching off of granule cells after intrahippocampal injection of colchicine eliciting the disappearance of evoked potentials and a deterioration in the development of a conditioned avoidance reflex in rats].

The aim of the work was to study the involvement in the process of learning of synapses between the perforant path and granular cells of the hippocampal dentate fascia for formation of conditioned reflex (CR) of active avoidance elaborated in response to electrostimulation of the perforant path. For solving this task, the property was used of the neurotoxin colchicine in a definite concentration to abolish selectively the fascia cells. One month after colchicine injection, destruction of granular cells was observed, disappearance of the dentate fascia focal evoked potentials and considerable deterioration of elaboration of active avoidance CRs. Administration of saline solution in control experiments did not elicit such changes. The obtained results show the decisive role of entorhinal input to the hippocampus in the used learning model.

Animals↗