Everybody who drank some beer knows that after a bottle of two you have to bring a visit to the toilet. When I was looking something up for my study I read why this happens. I will explain it here.

The main messenger which is involved in the process is Anti-Diuretic Hormone (ADH) also known as Vasopressin. The function of ADH in the body is to stimulate the resorption of water in the collecting ducts of the kidney. It does this by increasing the number of water channels in the cells of the collecting ducts. These water channels are normally stored inside these cells on vesicles where they stay in the membrane. Under the influence of ADH these vesicles are placed in the apical membrane of these cells allowing water to flow from the collecting duct into the cell.

ADH is syntesized in the hypothalamus in the cell body of neuroendocrine cells. There they are packed in granules and transported down the axons of these cells. The granules are stored in nerve terminals in the neurohypophysis.

ADH secretion is influenced by osmotic and hemodynamic factors but other factors can also alter ADH secretion, one of them is ethanol or alcohol which is one of the ingredients of beer.¹ Part of the effects of alcohol is due to co-binding on GABA receptors causing a prolonged opening of the Cl- channels mimicking the effects of GABA, another inhibitor of ADH. If the effects of alcohol become too strong it can block the neurons.² Since GABA is one of the main neurotransmitters in the brain, GABA might have a direct effect of inhibition on the neuroendocrine cells, but I didn't find any scientific evidence yet.