2.3. Porsolt swim test 2.4. Immunohistochemistry 2.5. Stereology N=∑Q×1/f×number of seriesN=∑Q×1/f×number of series Turn MathJax on where N is equal to the total number of neurons per brain; ∑Q is the number of neurons counted per rat and f is the fraction of the hypothalamic area analyzed.