Finegan, Matthew

English

Ithaca College

Fear	Factor:	Effects	of	the	Anti-Diabetic	Drug	Metformin	on	the	Production	and	Response	to	an	Anti-Predator	Alarm	Signal	in	Fathead	Minnows			Matthew	Finegan,	Susan	Allen-Gil					 Pharmaceutical	pollution	of	aquatic	ecosystems,	especially	by	endocrine	disruptors	–	a	class	of	chemical	that	have	been	shown	to	alter	normal	hormone	function,	is	becoming	a	worldwide	issue	of	growing	concern.	Pharmaceuticals	and	their	metabolites	enter	surface	waters	throughout	the	world	mostly	through	wastewater	treatment	effluent	discharged	from	facilities	lacking	the	ability	to	remove	trace	amounts	of	pharmaceuticals.	One	such	pharmaceutical	with	endocrine	disrupting	behavior	is	Metformin,	a	commonly	prescribed	anti-diabetic	medication	that	has	been	shown	to	induce	intersex	gonads	in	male	juvenile	fathead	minnows	at	a	concentration	found	in	treated	wastewater	effluent	(40	µg/L).	The	current	study	aims	to	determine	the	effects	of	metformin	exposure	on	epidermal	club	cell	investment	in	fathead	minnows.	Epidermal	club	cells	release	a	compound	when	damaged,	such	as	during	a	predator	attack,	that	triggers	an	anti-predator	response	in	nearby	minnows.	During	mating	season,	male	fathead	minnows	lose	the	ability	to	produce	these	club	cells,	and	thus	the	alarm	cue,	potentially	due	to	increased	testosterone	production.	If	a	hormone	such	as	testosterone	can	regulate	club	cells	investment,	an	endocrine	disruptor	such	as	metformin	may	be	able	to	alter	that	regulation.	For	this	study,	male	and	female	fathead	minnows,	both	in	their	mating	cycle	and	in	the	juvenile	phase	were	exposed	to	a	concentration	of	metformin	shown	to	cause	endocrine	disrupting	effects	in	previous	studies	(40	µg/L)	and	also	a	higher	dose	(100	µg/L).	During	this	exposure	period	secondary	sex	characteristics	were	recorded	to	judge	metformin	effects	on	sexual	development.	At	the	end	of	the	30-day	period	the	density	of	club	cells	in	skin	samples	was	modeled	by	examining	anti-predator	behavior	displayed	by	minnows	exposed	to	skin	extracts	from	the	tested	fish.	Changes	in	club	cell	investment	could	cause	harm	to	minnow	communities	due	to	changes	in	the	chemical	signaling	function	of	club	cells	associated	with	triggering	predator	avoidance	behavior,	and	additionally	decreasing	male	fathead	minnow	sexual	fitness.			

Fear Factor: Effects of the Anti-Diabetic Drug Metformin on the Production and Response to an Anti-Predator Alarm Signal in Fathead Minnows

https://digitalcommons.ithaca.edu/cgi/viewcontent.cgi?article=1062&context=whalen

Fear Factor: Effects of the Anti-Diabetic Drug Metformin on the Production and Response to an Anti-Predator Alarm Signal in Fathead Minnows

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