adipose tissue is recognized as the major source of leptin production in animals . as such , experiments were designed to determine the effect of niacin on leptin production in adipocytes . human adipocytes were obtained in accordance with standard methods . in brief , preadipocytes were collected from subcutaneous adipose tissue , following collagenase treatment . the preadipocytes were plated , and allowed to differentiate for 3 weeks , to form adipocytes . the adipocytes were then incubated , in 0 . 6 ml of dmem / f - 10 medium , to which 2 % bovine serum albumin was added . in addition , cultures either received 0 . 1 mm niacin , or did not . after 24 hours , the culture medium was analyzed for leptin , using a commercially available elisa kit . the results , which are presented in fig2 show that in the cultures to which niacin was added , leptin production increased 62 %. female apob / cetp double transgenic mice , obtained from a commercial supplier , were divided into 3 groups , and housed as six animals per cage . one group served as control , and received a standard diet , without added niacin . backs were shaved , and lotion was applied which was identical to the lotion applied to the third group , as described infra , without lauryl nicotinate ester . a second group received niacin , in the form of its sodium salt , dissolved in drinking water at a concentration of 0 . 75 % ( 0 . 63 % free acid ). the niacin intake of the animals was estimated based on water consumption and was approximately 1400 mg / kg of body weight , based upon an estimated consumption of 23 ml of water per 100 g of body weight , and an average body weight of 25 g . this is equivalent to about 8 . 4 g / day for a 70 kg human . see freireich , et al ., cancer chemother . rep . 50 : 219 - 244 ( 1966 ) incorporated by reference . for the third group , backs were shaved , and the lauryl nicotinate ester was applied to shaved areas , via 200 mg of lotion , containing 10 % ( wt / wt ) of the lauryl nicotinate ester . the amount of the ester applied is approximately 80 - 800 mg / kg , again assuming an average weight of 25 g . using freireich , supra , this is equivalent to a dose from about 0 . 48 to about 4 . 8 g / day / 70 kg human . the lotion was applied daily for 13 weeks . leptin levels in plasma were determined using a commercially available murine leptin radioimmunoassay . the ria was carried out on fasting ( 16 h ) blood samples obtained from the retroorbital plexus . the blood samples were collected and centrifuged at 2000 × g for 15 minutes to secure plasma . the results , summarized in fig3 show that oral niacin did increase the amount of circulating leptin , however , the lauryl nicotinate ester surpassed it in terms of the amount of circulating leptin . the experiments described in example 2 were continued , in the experiment described in this example . specifically , male balb / c mice were shaved , from the scapulae to tail bases . the subject animals then received topical application of the lauryl nicotinate ester lotion , described in example 2 , supra , or myristyl nicotinate ester lotion , in varying concentrations . controls received vehicle only . the lotion was applied at a dose of 4 ml / kg / mouse . serum leptin levels were measured , as described , supra . the results indicate that the serum leptin levels increased by 45 % in the subject animals which received the 10 % lauryl nicotinate ester lotion , while the increase for subject animals which received myristyl nicotinateesterwas 57 % ( for the 2 % formulation ), and 77 % ( for the 5 % formulation ). fig4 presents these results . the association of leptin with wound healing was discussed supra . this correlation was investigated in these experiments . mice were inflicted with full thickness wounds of about 6 mm in diameter , under anesthesia ( sodium phenobarbital ). they then received topical application of a 20 % nicotinate ester lotion , every day , for 14 days . the dosing was 100 μl for each application , with two applications every day . as a control , the lotion without the ester was used . wound diameter was measured every day . the results are presented in fig5 which shows that the mice which received the nicotinate ester containing formulations showed a reduction of wound thickness , as composed to controls . the lauryl ester was most effective with a 43 % reduction . when the serum leptin levels were measured , the mice which received the nicotinate ester application were found to have an increase of 44 % as compared to controls . these results are depicted in fig6 . the foregoing examples set forth various features of the invention which include , inter alia , a method for stimulating production of leptin in a subject in need thereof , by administering to said subject a leptin stimulating amount of a nicotinic acid or nicotinic acid derivative , such as a nicotinic acid ester . most preferably , this is a lauryl nicotinic acid ester , although other compounds , such as those described in the patent application cited supra may also be used . especially preferred are nicotinic acid per se , or nicotinic acid alkyl esters , where the ester moiety contains from 1 - 30 , optionally substituted , carbon atoms . more preferably , the alkyl moiety contains 1 - 22 carbon atoms , most preferably 1 - 18 carbon atoms . the subjects are preferably subjects suffering from a condition that can be alleviated by increased leptin levels , including those set forth in fig1 improved immune function , skin epitheliation , hair follicle cycling , inhibition of tumor formation , such as skin tumor formation , and so forth . the mode by which the nicotinic acid or ester is administered to the subject may vary . oral , time release , intravenous , intradermal , and other forms of administration are contemplated , as topical administration . such topical administration may be via a creme , lotion , liquid , aerosol , body wash , mouthwash , toothpaste , gavage , or other form of topical administration . for example , in the case of timed released application , “ patches ,” such as the type used in timed release of nicotine , bandages , wraps , and so forth may be employed . the nicotinic acid ester is administered in an amount sufficient to stimulate leptin production . the dose used can and will vary ; however , formulations should deliver , e . g ., doses ranging from about 0 . 1 to about 10 g / day / 70 kg body weight , more preferably from about 0 . 1 to about 7 g / day / 70 kg body weight , most preferably from about 0 . 4 to about 5 / g / day / 70 kg body weight . as indicated , supra , the stimulation of leptin production can lead , in addition to the effects associated with leptin previously , to regression of skin tumors , skin homeostases and remodeling , epidermal barrier development , wound healing , and hair growth . other applications will be clear to the skilled artisan and need not be elaborated herein .
the invention relates to the use of nicotinic acid and nicotinic acid esters , such as nicotinic acid alkyl esters , to increase the amount of leptin in a subject . as a result , one can treat conditions , such as conditions characterized by wounds , by administering sufficient amounts of nicotinic acid or nicotinic acid ester to increase leptin levels to alleviating amounts . various conditions and modes of treatment are disclosed .