The guinea-pig is not a rodent

Article Abstract:

A phylogenetic tree, based on the sequence of mitochondrial DNA (mtDNA) of the guinea-pig, Cavia porcellus, and other mammals, shows that the guinea-pig is not a member of the Rodentia family. It belongs to an outgroup of the group containing Perissodactyla, Lagomorpha, Primates, Artiodactyla, Cetacea, and Carnivora. The mtDNA is analyzed by the maximum-parsimony method, protein maximum-likelihood method, and stationary Markov model to remove differences due to difference in analysis method. Results of the study show that the guinea-pig should be put in a mammalian order distinct from Rodentia.

Usage, Genetic aspects, Mitochondrial DNA, Phylogeny, Mammals

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Behavioural stress facilitates the induction of long-term depression in the hippocampus

Article Abstract:

Behavioural stress inhibits the induction of persistent activity-dependent rises in synaptic efficacy, including long-term potentiation (LTP), but there are questions as to whether stress can also affect the ability to induce decreases in long-term depression (LTD). An experiment found that the induction of stable homosynaptic LTD in the CA1 region of the hippocampus in rats is facilitated by mild naturalistic stress.

Stress (Physiology), Hippocampus (Brain)

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Endogenous dynorphins inhibit excitatory neurotransmission and block LTP induction in the hippocampus

Article Abstract:

A study conducted on the guinea-pig hippocampus reveals the function of prodynorphin-derived opioid peptides. The physiological stimulation of the dentate granule cells containing dynorphin activates the K1 opioid receptors of the dentate gyrus in its molecular layer. The endogenous dynorphins act as retrograde, inhibitory neurotransmitters in the hippocampal circuit.

Peptides, Peptide synthesis

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