Answer:
The answer is that NE injection has inhibitory effects on the paraventricular nucleus VPN.
Explanation:
It can be said that the destruction of the paraventricular nucleus (PVN) would produce a hyperphagia, on the other hand, the injection of norepinephrine (NE) would increase the feeding in the rats. This is because NE injection has inhibitory effects on the paraventricular nucleus. If neuronal activation in the paraventricular nucleus is increased, food intake by rats would be decreased.
Answer:
Epistatic interaction of the two genes
Explanation:
In epistasis, the interaction between genes contradics one another, in essence, one gene masks the interference with the expression of another gene. As such any time two different genes contribute and have effects to a single phenotype and their effects are not merely additive, those genes are said to be epistatic.
Phoebes Levine proposed the polynucleic model (around 1910!).