Prostanoid Receptors in Human Hair follicles: How Prostaglandins Affect Hair Growth
Prostaglandins are naturally occurring, hormone-like fatty acids that regulate a variety of physiological reactions, such as: blood pressure, platelet aggregation, inflammatory response, etc. 
One example of how prostaglandins affect hair growth is shown when a drug is administered that promotes an increase in the action of the prostaglandin F(2alpha) receptor (FP) for the treatment of intraocular pressure (glaucoma), providing a side-effect of hair growth. [1], [2]
Other types of prostaglandins have been shown to affect hair growth,such as prostaglandin E receptors (EP2 through 4) and prostaglandin D(2) receptor and prostanoid thromboxane A(2) receptor. Of note, prostaglandin D(2) has been recently shown to be significantly elevated in balding scalps. [3]
Resolving the Prostalgandin Problem with Krill Oil
Prostaglandins PGD2 and PGE2 can be reduced by both docosahexaenoic acid and eicosapentaenoic acid, found in Krill oil. These fatty acids are efficiently incorporated into cellular phospholipids at the expense of arachidonic acid. [4] 
The process of an inflammatory response in an infection can be stimulated by the metabolism of the omega-6 fatty acid, arachidonic acid, into the eicosanoid prostaglandin-D2 (PGD2) by way of the cyclooxygenase (COX) enzymes. 
However, the omega-3 fatty acid, eicosapentaenoic acid (EPA) can be utilized as an alternative substrate for COX enzymes. In turn this inhibits the migration of neutrophils across endothelial cells by antagonising the PGD2 receptor. [5]
[1]. Exp Dermatol. 2008 Jan;17(1):63-72.
[2]. Exp Dermatol. 2007 Sep;16(9):762-9.
[3]. Sci Transl Med. 2012 March 21; 4(126): 126ra34.
[4]. J Inflamm Res. 2012; 5: 37–50.
[5]. PLoS Biol. 2009 August; 7(8): e1000177.